Forrest arranged for us to visit a house he is working on with a heat recovery ventilation (HRV) system, so that we could get an idea how noisy HRV is. On Friday, we drove up to the place. The house is a job that Forrest has almost completed. There are still a few items yet left to finish, and the owners had graciously consented to let us check the HRV out since they are away.
Surprisingly, the HRV system is almost silent, even on the highest setting. The only time I could hear anything from it was when I was standing directly under the vent in the bathroom, and that was just the sound of the air coming out of the duct. Forrest also turned on the forced air furnace, and that was much noisier, I guess because the amount of air being pushed through the ducts is larger. Paul, Forrest's partner, opened the attic and let us take a look at the HRV in operation. With the attic door open, you could hear a distinctive hum, but the vibration was not transferred to the structure of the house, unlike a forced air furnace, because the HRV is mounted from chains connected to the frame of the house with springs. This acted as a sound damper, removing any vibration. Sound propagation through the HRV ducts is also limited by putting in lots of right angle turns. These break off the paths through which sound waves can easily propagate.
We still have some concern about the geothermal heat pump. The big pump that sends the heat exchanger fluid into the ground and the compressor that either extracts the heat from the fluid or puts it in are both likely to generate vibrations. Just like a forced air furnace, they can't be hung from the frame of the house because they are too heavy, though there are some measures that can be taken to isolate the heat pump from the frame of the house. We discussed putting the heat pump in the garage and running an insulated line to the heat exchanger in the mechanical closet instead of mounting the heat pump in the mechanical closet. We need to have the heat exchanger in the mechanical closet because that is where the manifold is for the radiant heat system. Of course, we would also need to figure out how to engineer the air conditioning. The air conditioning is never likely to be quiet, since, just like a forced air furnace, it will be shoving large amounts of air through the ducts. Putting that in the mechanical closet seems unavoidable if we will be using the old forced air ducts for air conditioning. They all converge on the mechanical closet because that is where the old forced air furnace was, though the ducts that were under the house have been removed and will probably need to be replaced.
I also asked Forrest if we could connect the air conditioning to a ventilation system with a heat exchanger. This would allow us to get fresh air into the house in summer through the air conditioning rather than opening the windows or running the HRV. He said that this typically isn't done, that the warm air return for the squirrel cage blower on the air conditioning comes from within the house, just as with a forced air furnace. In fact, the air conditioning (or forced air furnace if you have that) and the HRV are two separate sets of ventilation ducts. Somehow, one would think that somebody would have been smart enough to combine the two.
I continue to be amazed about the lack of efficiency in planning HVAC (heating, ventilation, and air conditioning) systems. Stuff that seems obvious to me as an engineer with a systems orientation never seems to have crossed the minds of the people who designed these systems. Every function is in a separate box. It is no wonder that over 40% of the energy in this country is used by buildings. Without proper integration of these systems, there is redundant energy use. For example, the squirrel cage blower on a forced air furnace and the HRV system are essentially doing the same thing: pushing conditioned air through ducts. Why not combine them, and run the cold air return through a heat exchanger on the furnace and out, and draw in outside air through the heat exchange and into the furnace?
Anyway, we've told Forrest to move ahead with the geothermal planning. We signed the design contract two weeks ago, but put it on hold pending an opportunity to experience how much noise an HRV system really makes. This means the final design will be pushed out by at least two weeks (and if we are lucky, only two weeks), meaning the start date is likely to be late June. Four months puts us into October. If the project is delayed (as usually in is the case in my experience) we could end up moving back in around Christmas. Considering we are planning on living in the back bedroom and also mostly outside during the summer, things could get a little tight come October when the weather starts to get cold again.
Saturday, April 24, 2010
Monday, April 19, 2010
One Slice of Bread
Today I got a letter from PG&E telling me that they had decided how much they will pay me for the extra power my solar PV system generates, above what I use, starting next year. A couple months ago they sent a letter saying that they would start paying their net metering customers in 2011 at the annual true-up date. Up until this year, our solar PV system has been generating between $30-$134 more in credit than our house consumes. We kind of viewed at as our contribution to greening the planet since it hasn't been all that much.
The house isn't carbon neutral, though, we use around 1000 kwh/year more power from the grid than we generate. The difference is that we generate more power during the summer in the afternoon and evening than we do during the winter and in the morning. Due to time of day metering, PG&E pays us around $0.30/kwh for summer solar-generated peak power but only charges us around $0.09 for offpeak and winter power. It's a pretty good deal for us all things considered, though it wouldn't be if we had to use air conditioning during week days in the summer. We get the favorable rate because the folks in the Central Valley need to have their air conditioners on all day. So they use more power during the peak.
In their letter, PG&E proposes to pay its net metering customers $0.08/kwh for credit they incur above what they use. They claim this is consistent with the California Public Utilities Commission mandate in AB 920 (the law that requires net metering customers to be compensated for unused credit they incur) requiring the compensation to "set the rate for generation, including renewable characteristics, without shifting costs to other customers". I have a bit of trouble seeing how their math works out. If the power is worth $0.30/kwh to them in the summer, then how does it suddenly become worth only $0.08/kwh when they need to pay me hard money for it instead of trade? It's not like they don't have the information in their billing systems about when I generate the power, they could easily prorate the reimbursement based on time of use metering, just like they do with the cost.
The larger issue here of course is that such measly reimbursement rates aren't likely to encourage homeowners or businesses to install more solar. But this has been consistent with PG&E's position all along. The reimbursement rates quoted in their tenders for renewable energy systems over 1 mw a few years ago were similarly unattractive for investors, and they were fixed for 20 years. Contrast this with Germany and Spain, where feed-in tariffs for renewable power 3-4x fossil-generated power, set for 30 years have seen an explosion of investment in renewable systems. The net metering reimbursements are a kind of feed-in tariff, but not a particularly attractive one for individual investors, such as myself, who would like to maximize our solar generating potential but also earn some money on it. PG&E has been happy to provide net metering in trade, but when it comes to paying real money for distributed, small-scale power generation, well, that's another story.
I probably shouldn't complain, since the credit is actually just a mathematical construct due to PG&E's tariff structure. In the spirit of "half a loaf is better than none", I guess I'll take this slice of bread they're offering with gratitude, and hope the State Legislature and PG&E figures out some other way to encourage more solar.
The house isn't carbon neutral, though, we use around 1000 kwh/year more power from the grid than we generate. The difference is that we generate more power during the summer in the afternoon and evening than we do during the winter and in the morning. Due to time of day metering, PG&E pays us around $0.30/kwh for summer solar-generated peak power but only charges us around $0.09 for offpeak and winter power. It's a pretty good deal for us all things considered, though it wouldn't be if we had to use air conditioning during week days in the summer. We get the favorable rate because the folks in the Central Valley need to have their air conditioners on all day. So they use more power during the peak.
In their letter, PG&E proposes to pay its net metering customers $0.08/kwh for credit they incur above what they use. They claim this is consistent with the California Public Utilities Commission mandate in AB 920 (the law that requires net metering customers to be compensated for unused credit they incur) requiring the compensation to "set the rate for generation, including renewable characteristics, without shifting costs to other customers". I have a bit of trouble seeing how their math works out. If the power is worth $0.30/kwh to them in the summer, then how does it suddenly become worth only $0.08/kwh when they need to pay me hard money for it instead of trade? It's not like they don't have the information in their billing systems about when I generate the power, they could easily prorate the reimbursement based on time of use metering, just like they do with the cost.
The larger issue here of course is that such measly reimbursement rates aren't likely to encourage homeowners or businesses to install more solar. But this has been consistent with PG&E's position all along. The reimbursement rates quoted in their tenders for renewable energy systems over 1 mw a few years ago were similarly unattractive for investors, and they were fixed for 20 years. Contrast this with Germany and Spain, where feed-in tariffs for renewable power 3-4x fossil-generated power, set for 30 years have seen an explosion of investment in renewable systems. The net metering reimbursements are a kind of feed-in tariff, but not a particularly attractive one for individual investors, such as myself, who would like to maximize our solar generating potential but also earn some money on it. PG&E has been happy to provide net metering in trade, but when it comes to paying real money for distributed, small-scale power generation, well, that's another story.
I probably shouldn't complain, since the credit is actually just a mathematical construct due to PG&E's tariff structure. In the spirit of "half a loaf is better than none", I guess I'll take this slice of bread they're offering with gratitude, and hope the State Legislature and PG&E figures out some other way to encourage more solar.
Monday, April 12, 2010
Noise
Last week on Wed. we had a meeting with Forrest, our architect, to discuss the geothermal design contract. The contract had a lot of assumptions about our situation that weren't true, but Forrest said that his experience with the company was generally good, except for the design contracts. They tended to do this - put lots of irrelevant stuff in the contract - just to make it look more precise, though, actually, since it didn't correspond to our situation, it made the contract look inaccurate. We decided to take his word for it and go ahead with the design.
Later in the meeting, we reviewed a list of items that I have been accumulating. One of them involved soundproofing the geothermal heat pump and HRV system to ensure that they do not generate a lot of noise. Forrest told us that the HRV systems were, in fact, noisy but that there were measures, such as bending the pipe 90 degrees at the vent, to reduce propagation of noise from the HRV unit to the vent, although sometimes this couldn't be done. HRVs are mechanical ventilation and anybody who works in an office building knows what that sounds like. Basically you are working with the sound of a fan running in the ceiling all day as the accompaniment to your creative thoughts. Forced air heating sounds the same way.
Our house is particularly susceptible to noise, since it was built in the 1970's and there is nothing put into the structure to inhibit vibrations from one part of the house - say, the running fridge in the kitchen downstairs - from propagating to another - say, my office upstairs. When we had radiant heat put in a few years ago, we were astounded how quiet the house became in winter. It's not that you can't hear anything, the furnace still makes a low frying noise from the burning gas, it is just much quieter than having a squirrel cage blower whaling away in the mechanical closet, and the sound of the air whooshing out the vents. There's also the almost inaudible sound of the solar hot water pumps usually in the afternoon of sunny days, and, of course the fridge. But all these add up to very little noise, and the noise is also intermittent. With tightly insulated houses, the HRV system must be on all the time, otherwise the air quality inside the house suffers.
I found this a little hard to understand, since the German Passivhaus standard requires HRV. Passivhaueser (in German, "passive houses") are basically so tightly insulated that they require no supplemental heating beyond that from the appliances (like the fridge) and people within them, even in the cold German winters. An HRV system takes fresh and possibly cold air from outside, circulates it through a heat exchanger with stale air from inside on the other side of the heat exchanger, and exhausts the fresh air into the house and the stale air to outside. In this way, the occupants get fresh air but the heat is retained. Our insulation would not be that tight, since we have the solarium on the back that probably leaks heat and air, and also, we are not reinsulating the master suite nor one wall in the kitchen, but nevertheless, the amount of insulation we are putting in is enough that it could cut down on the amount of air infiltration sufficiently to allow air quality to suffer. We already have a problem with cooking odors lingering into the next day.
Now Germans are particular about noise in their houses. Even regular German houses are very solidly built in comparison to American houses, usually from ceramic bricks shaped like cement blocks, and they have heating systems that run on oil or gas that either use radiant heat as we do or radiators under windows. American houses are flimsy in comparison. All this mass makes for a very quiet house indeed, very little traffic noise penetrates. So I found it hard to believe that HRV systems could be noisy, the Germans who are now building lots of Passivhaueser, would never stand for it.
Naturally, I went on line to try to figure out what the problem was. In particular, I wanted to find out how much noise HRV systems emitted. The specs for the unit Forrest recommended had no noise rating. But - surprise! - the same thing was true of every single unit manufactured in the US or Canada that I looked at (and I checked 10)! The only unit sold it the US that had a noise rating was the Panasonic WhisperQuiet(tm), which is made in Japan. The WhisperQuiet is actually a bathroom ventilator, because it exhausts directly out of the unit rather than through a duct, so it is unsuitable for our situation, but the noise rating (though in an unusual measurement) was quite good.
Even more surprisingly, every single unit manufactured in Germany and sold in the other countries of the EU had a noise rating on it! The quietest I found were products manufactured by Paul Lueftung. There are various models, but the noise rating ran from 18 db to around 33 db. This is about the amount of noise in a quiet room, and these units are in fact used in Passivhaueser. Products from other companies typically started at 35 db. Unfortunately, the units conform to the European power standard - 230V/50Hz. In the US, we can get 220V which is probably OK, but 60Hz which might be a problem for an AC motor. The units may have DC motors and a power supply, in which case, we could convert them to our power standard. I need to look into this as a possibility.
It seems rather strange that the US manufactured products don't come with a noise rating. Don't Americans care about noise? I guess not since they put up with noisy forced air heating and noisy ventilation in offices, or maybe the sound of all that electricity being used makes people feel like Progress is happening. But I suspect the answer is much simpler: the German government requires manufacturers to include noise in their technical specs whereas the American government doesn't. Guv'ment regulation! The German technical specifications were also considerably more complete and prominently available on the manufacturer's web sites. In several cases, it was difficult to find the American manufacturer's specs, and they were quite skimpy, for example, the noise rating was listed as "quiet". Of course, your "quiet" might be my "noisy", a db rating is much more objective.
I also looked briefly into noise from geothermal heat pumps, there the situation was the same. Lots of web sites talked about how little noise they generated outside, in comparison to air source heat pumps, but nothing about the actual noise generated by the heat pump itself. I figure that there are three components to noise from the heat pump: the pump circulating the heat transfer fluid into the ground and out, the compressor, and the forced air system (if the system is forced air). On heat mode, our system won't have the latter since we use radiant heat, but we would have the first two. On air conditioning mode, of course, we would have to put up with all three, but there is nothing we can do about that, it is not possible to use a radiant heat system for cooling. I figure that the compressor can't be much noisier than a fridge and the heat transfer fluid pump should be about the same as the solar hot water pumps, but then who knows? A fridge we got in our old house was so noisy that we got rid of it after a couple years, we could not afford to do that with a heat pump. The heat pump will probably have to be American manufactured because the electrical system is probably too complicated to convert, so it could be bad.
Anyway, we asked Forrest to hold off on the geothermal design and the HRV design until we get more clarity about this issue. In the worst case (i.e. we can't get a quiet HRV system), we can back off the insulation and just do under the floor (where the current fiberglass batting causes lots of radiant heat to leak in to the crawlspace) and on the central hallway ceiling, which must be replaced due to cracking, then we probably don't need HRV. As for the geothermal, maybe we could mount the compressor and heat transfer loop pump in the garage, and the heat exchanger in the mechanical closet. Or possibly get some kind of soundproofing under the compressor so it doesn't shake the floor.
Later in the meeting, we reviewed a list of items that I have been accumulating. One of them involved soundproofing the geothermal heat pump and HRV system to ensure that they do not generate a lot of noise. Forrest told us that the HRV systems were, in fact, noisy but that there were measures, such as bending the pipe 90 degrees at the vent, to reduce propagation of noise from the HRV unit to the vent, although sometimes this couldn't be done. HRVs are mechanical ventilation and anybody who works in an office building knows what that sounds like. Basically you are working with the sound of a fan running in the ceiling all day as the accompaniment to your creative thoughts. Forced air heating sounds the same way.
Our house is particularly susceptible to noise, since it was built in the 1970's and there is nothing put into the structure to inhibit vibrations from one part of the house - say, the running fridge in the kitchen downstairs - from propagating to another - say, my office upstairs. When we had radiant heat put in a few years ago, we were astounded how quiet the house became in winter. It's not that you can't hear anything, the furnace still makes a low frying noise from the burning gas, it is just much quieter than having a squirrel cage blower whaling away in the mechanical closet, and the sound of the air whooshing out the vents. There's also the almost inaudible sound of the solar hot water pumps usually in the afternoon of sunny days, and, of course the fridge. But all these add up to very little noise, and the noise is also intermittent. With tightly insulated houses, the HRV system must be on all the time, otherwise the air quality inside the house suffers.
I found this a little hard to understand, since the German Passivhaus standard requires HRV. Passivhaueser (in German, "passive houses") are basically so tightly insulated that they require no supplemental heating beyond that from the appliances (like the fridge) and people within them, even in the cold German winters. An HRV system takes fresh and possibly cold air from outside, circulates it through a heat exchanger with stale air from inside on the other side of the heat exchanger, and exhausts the fresh air into the house and the stale air to outside. In this way, the occupants get fresh air but the heat is retained. Our insulation would not be that tight, since we have the solarium on the back that probably leaks heat and air, and also, we are not reinsulating the master suite nor one wall in the kitchen, but nevertheless, the amount of insulation we are putting in is enough that it could cut down on the amount of air infiltration sufficiently to allow air quality to suffer. We already have a problem with cooking odors lingering into the next day.
Now Germans are particular about noise in their houses. Even regular German houses are very solidly built in comparison to American houses, usually from ceramic bricks shaped like cement blocks, and they have heating systems that run on oil or gas that either use radiant heat as we do or radiators under windows. American houses are flimsy in comparison. All this mass makes for a very quiet house indeed, very little traffic noise penetrates. So I found it hard to believe that HRV systems could be noisy, the Germans who are now building lots of Passivhaueser, would never stand for it.
Naturally, I went on line to try to figure out what the problem was. In particular, I wanted to find out how much noise HRV systems emitted. The specs for the unit Forrest recommended had no noise rating. But - surprise! - the same thing was true of every single unit manufactured in the US or Canada that I looked at (and I checked 10)! The only unit sold it the US that had a noise rating was the Panasonic WhisperQuiet(tm), which is made in Japan. The WhisperQuiet is actually a bathroom ventilator, because it exhausts directly out of the unit rather than through a duct, so it is unsuitable for our situation, but the noise rating (though in an unusual measurement) was quite good.
Even more surprisingly, every single unit manufactured in Germany and sold in the other countries of the EU had a noise rating on it! The quietest I found were products manufactured by Paul Lueftung. There are various models, but the noise rating ran from 18 db to around 33 db. This is about the amount of noise in a quiet room, and these units are in fact used in Passivhaueser. Products from other companies typically started at 35 db. Unfortunately, the units conform to the European power standard - 230V/50Hz. In the US, we can get 220V which is probably OK, but 60Hz which might be a problem for an AC motor. The units may have DC motors and a power supply, in which case, we could convert them to our power standard. I need to look into this as a possibility.
It seems rather strange that the US manufactured products don't come with a noise rating. Don't Americans care about noise? I guess not since they put up with noisy forced air heating and noisy ventilation in offices, or maybe the sound of all that electricity being used makes people feel like Progress is happening. But I suspect the answer is much simpler: the German government requires manufacturers to include noise in their technical specs whereas the American government doesn't. Guv'ment regulation! The German technical specifications were also considerably more complete and prominently available on the manufacturer's web sites. In several cases, it was difficult to find the American manufacturer's specs, and they were quite skimpy, for example, the noise rating was listed as "quiet". Of course, your "quiet" might be my "noisy", a db rating is much more objective.
I also looked briefly into noise from geothermal heat pumps, there the situation was the same. Lots of web sites talked about how little noise they generated outside, in comparison to air source heat pumps, but nothing about the actual noise generated by the heat pump itself. I figure that there are three components to noise from the heat pump: the pump circulating the heat transfer fluid into the ground and out, the compressor, and the forced air system (if the system is forced air). On heat mode, our system won't have the latter since we use radiant heat, but we would have the first two. On air conditioning mode, of course, we would have to put up with all three, but there is nothing we can do about that, it is not possible to use a radiant heat system for cooling. I figure that the compressor can't be much noisier than a fridge and the heat transfer fluid pump should be about the same as the solar hot water pumps, but then who knows? A fridge we got in our old house was so noisy that we got rid of it after a couple years, we could not afford to do that with a heat pump. The heat pump will probably have to be American manufactured because the electrical system is probably too complicated to convert, so it could be bad.
Anyway, we asked Forrest to hold off on the geothermal design and the HRV design until we get more clarity about this issue. In the worst case (i.e. we can't get a quiet HRV system), we can back off the insulation and just do under the floor (where the current fiberglass batting causes lots of radiant heat to leak in to the crawlspace) and on the central hallway ceiling, which must be replaced due to cracking, then we probably don't need HRV. As for the geothermal, maybe we could mount the compressor and heat transfer loop pump in the garage, and the heat exchanger in the mechanical closet. Or possibly get some kind of soundproofing under the compressor so it doesn't shake the floor.
Sunday, March 14, 2010
The Electric Car Resurrection II: The Hero's Path
While I was researching conversions, I found out that the husband of a friend of my wife's was planning to do a conversion. Steve Schmidt and his son Eric (a high schooler) were well into plans to locate a small junked sports car in good condition and convert from ICE to EV. Now, Steve's skill with tools is far in excess of mine, and Eric is no slouch himself. Eric recently served as lead engineer on one of the components in his high school robotics team's entry into the national robotics competition. I'd last checked in with Steve two years or so ago, so a few weeks ago I stopped by to see how the project came out.
Steve and Eric started planning the conversion in the spring of 2007. They ordered the batteries in September, 2007 and by February 2008 the batteries had arrived. The conversion work itself followed quickly, by May the car was running.
The "donor" was a 1976 MG midget, located from a junk yard and bought for $800. Here you can see it relaxing in the grass:
The first order of business was restoring the car's gasoline engine. This they did. Here you can see the car with the engine restored, minus the radiator:
Naturally, if you want to get a car relicensed in California, you have to have a smog inspection. Since this car had no pollution controls - catalytic converter, filters on the engine to catch gasoline vapors, etc. - it was labeled a "gross polluter". But they did manage to get it relicensed. The work on the gasoline engine wasn't all lost, they managed to sell the engine on EBay which helped finance the electric components.
After the car was running on gasoline, they removed the engine and started the electric conversion. The most difficult thing about the conversion was connecting the electric motor to the transmission and clutch. Most electric conversions remove the transmission and clutch. Because an electric motor has essentially infinite torque at zero rotation, there is no need for a transmission, unlike a gasoline motor. But Eric really wanted the ability to shift, so they kept the transmission. The connection required them to get a specially machined metal plate to match up the motor to the transmission. This plate is actually a requirement for any electric conversion, but theirs was a bit more tricky because they wanted to keep the transmission.
The most expensive part of any electric conversion is the battery pack. Unlike most hobbyist conversions, the Schmidts decided to go with lithium polymer batteries, having lithium cobalt oxide anodes. They ordered their pack from ABAT, a Chinese company, and the batteries also came with a battery controller for charging. The pack consists of 66 40 amp-hour cells arranged 2x33. The result is 80 amp-hours at 130 volts, or 10 kWh. Here's a picture of the battery box in the front:
There's another battery box in the back where the gas tank used to be.
Shortly after they got the car running, 2 cells went bad and were replaced by ABAT on warranty. They now have two other cells that don't charge up as smoothly as the rest. the line of small dots you see on the front of the battery box are ports they use for balancing the charge across the two strings of batteries. The battery pack cost around $10.5K and weights 200 lbs. though all together, it did not add extra weight to the car. The car is actually slightly lighter than the original but still has the original suspension.
The other electrical components include an Advanced DC 8", 85 hp motor and a Curtis 1221-C controller. The controller is a bottleneck, it will not let the motor draw enough current to get that slapped back into the seat kind of acceleration that electric cars are known for. Steve told me that there is another controller, made by Zilla, which is much better but it is considerably more expensive and also isn't manufactured any more, so it can only be bought used. Because the electrical system is DC, there is no regenerative braking, such as the Prius and other commercial hybrids have.
The range of the car is around 45 miles per charge, top speed probably over 65 mph but they have never tried it. Steve and Eric told me of their adventure with getting the electric car smogged. This sounds like a contradiction, but after they removed the engine, they had to have it retested and certified as not being a polluter. DMV was around 20 miles away, so they figured they could just make it. On the way back, they almost made it when they realized they were running out of charge. They parked the car at a laundromat and plugged in for a couple hours. After that, they made it home. But the car is mostly used by Eric for commuting 5 miles or so to school and back, so range isn't really a problem.
Eric and Steve split the financing. Eric paid for the ICE components, including a new set of seats from a Mazda Miata and a stereo, and Steve paid for the electric components. In all, the cost came out to $18,266.
After we were done talking, Eric took me out for a spin. The land around their house is hilly, but the car had no problems negotiating the hills. And despite the drawbacks of the Curtis controller, the acceleration seemed just fine.
If you want to find out more about the Schmidt's conversion, check out their Web page at EValbum. com.
Steve and Eric started planning the conversion in the spring of 2007. They ordered the batteries in September, 2007 and by February 2008 the batteries had arrived. The conversion work itself followed quickly, by May the car was running.
The "donor" was a 1976 MG midget, located from a junk yard and bought for $800. Here you can see it relaxing in the grass:
Naturally, if you want to get a car relicensed in California, you have to have a smog inspection. Since this car had no pollution controls - catalytic converter, filters on the engine to catch gasoline vapors, etc. - it was labeled a "gross polluter". But they did manage to get it relicensed. The work on the gasoline engine wasn't all lost, they managed to sell the engine on EBay which helped finance the electric components.
After the car was running on gasoline, they removed the engine and started the electric conversion. The most difficult thing about the conversion was connecting the electric motor to the transmission and clutch. Most electric conversions remove the transmission and clutch. Because an electric motor has essentially infinite torque at zero rotation, there is no need for a transmission, unlike a gasoline motor. But Eric really wanted the ability to shift, so they kept the transmission. The connection required them to get a specially machined metal plate to match up the motor to the transmission. This plate is actually a requirement for any electric conversion, but theirs was a bit more tricky because they wanted to keep the transmission.
The most expensive part of any electric conversion is the battery pack. Unlike most hobbyist conversions, the Schmidts decided to go with lithium polymer batteries, having lithium cobalt oxide anodes. They ordered their pack from ABAT, a Chinese company, and the batteries also came with a battery controller for charging. The pack consists of 66 40 amp-hour cells arranged 2x33. The result is 80 amp-hours at 130 volts, or 10 kWh. Here's a picture of the battery box in the front:
There's another battery box in the back where the gas tank used to be.
Shortly after they got the car running, 2 cells went bad and were replaced by ABAT on warranty. They now have two other cells that don't charge up as smoothly as the rest. the line of small dots you see on the front of the battery box are ports they use for balancing the charge across the two strings of batteries. The battery pack cost around $10.5K and weights 200 lbs. though all together, it did not add extra weight to the car. The car is actually slightly lighter than the original but still has the original suspension.
The other electrical components include an Advanced DC 8", 85 hp motor and a Curtis 1221-C controller. The controller is a bottleneck, it will not let the motor draw enough current to get that slapped back into the seat kind of acceleration that electric cars are known for. Steve told me that there is another controller, made by Zilla, which is much better but it is considerably more expensive and also isn't manufactured any more, so it can only be bought used. Because the electrical system is DC, there is no regenerative braking, such as the Prius and other commercial hybrids have.
The range of the car is around 45 miles per charge, top speed probably over 65 mph but they have never tried it. Steve and Eric told me of their adventure with getting the electric car smogged. This sounds like a contradiction, but after they removed the engine, they had to have it retested and certified as not being a polluter. DMV was around 20 miles away, so they figured they could just make it. On the way back, they almost made it when they realized they were running out of charge. They parked the car at a laundromat and plugged in for a couple hours. After that, they made it home. But the car is mostly used by Eric for commuting 5 miles or so to school and back, so range isn't really a problem.
Eric and Steve split the financing. Eric paid for the ICE components, including a new set of seats from a Mazda Miata and a stereo, and Steve paid for the electric components. In all, the cost came out to $18,266.
After we were done talking, Eric took me out for a spin. The land around their house is hilly, but the car had no problems negotiating the hills. And despite the drawbacks of the Curtis controller, the acceleration seemed just fine.
If you want to find out more about the Schmidt's conversion, check out their Web page at EValbum. com.
Thursday, March 11, 2010
More Spark Plugs
Well, if you have been following the saga of the shorting spark plug here and here you'll remember that the high performance spark plugs I got from Enerplus (called Pulstar) shorted and burned out my ignition coil, but the company reimbursed me for the plugs and the coil replacement. My mechanic put stock plugs back into the 2002 Prius, and since then I've been sadly watching as the gas mileage deteriorated by 0.1 mpg per month. And pushing on the steering wheel and saying "come on, come on..." as the car struggled onto the freeway in the morning.
Anyway, I finally broke down a couple weeks ago and bought another set of Pulstar plugs. Enerplus has been working on improving them, and version 2.0 supposedly has a longer lifetime as well as a fix for the occasional high resistance problem that plagued the original plugs I had. Plus they are less expensive.
I recently had the car in for a 75,000 mile checkup and asked my mechanic to put them in again. He looked at me a bit funny and asked if I was sure, but when I told him that the company had made good on their guarantee, he was relieved. I've reset the mileage, hopefully it will get back up to 46 mpg it was before the resistance started creeping up last summer.
Anyway, I finally broke down a couple weeks ago and bought another set of Pulstar plugs. Enerplus has been working on improving them, and version 2.0 supposedly has a longer lifetime as well as a fix for the occasional high resistance problem that plagued the original plugs I had. Plus they are less expensive.
I recently had the car in for a 75,000 mile checkup and asked my mechanic to put them in again. He looked at me a bit funny and asked if I was sure, but when I told him that the company had made good on their guarantee, he was relieved. I've reset the mileage, hopefully it will get back up to 46 mpg it was before the resistance started creeping up last summer.
Saturday, March 6, 2010
System Remodel Coming
My wife and I are in the process of planning a system remodel, or deep energy retrofit, on the house. The idea sprang out of a problem we are having with the cathedral ceiling in the hall that runs the length of the house. The ceiling is cracking along the ridge and on one seam near the north side. According to a structural engineer we had look at the problem, the cracking is happening because the ceiling is spreading. When we moved into the house in 2003, we had the rotting, termite-ridden shake roof removed and replaced with a nice 40 year composite roof. The plywood decking increased the weight of the roof, and since our house was built in the 1970's before they really had the technology of cathedral ceilings down, there is no steel in the ceiling supports. So the weight causes the wood to compress and spread. We had a couple contractors come in last summer and give us bids, and included in the bids was the cost of taking the dry wall off the rest of the ceilings in the house and reinsulating with closed cell foam - a messy job at best - to increase the heat retention in winter. The bids came in around $100K, a lot of money just for some drywall work and insulation.
We decided to think about what more we could do that would move our house closer to our goal of net zero energy. The experience with getting bids on the ceiling showed us that we were about at the limit of what we could do by attacking the problem piecemeal. Most contractors are clueless about how to do good insulation. When we had the kitchen ceiling redone a couple years ago to get rid of leaky can lights, I had to walk the contractor through what he needed to do to get a tight seal, though he is otherwise quite competent and is the most accurate in doing bids that I have found. We decided to work with an architectural firm that has lots of experience with green architecture, Vox Design in downtown Mountain View. Vox is run by Randy Potter and Forrest Linebarger. I know Randy from my time on the Mountain View Sustainability Task Force, we ended up working with Forrest because he had the most time. We've had four meetings with Forrest since Christmas and are getting close to finalizing the design.
The first order of business before Christmas was to get an "as-built" CAD model of the house, since we had no plans. One Saturday, a guy came over and measured the whole house, checked out all the various kinds of surface (hardwood floor, etc.). Our house has a lot of odd corners here and there, many of the walls don't exactly line up as you might expect, so he had some difficulty getting an accurate plan. This is somewhat of an architectural feature, not a function of sagging over time or anything like that. The house is in a style called "Sea Ranch" after a development along the Mendocino Coast that was built in the 1970's and influenced a lot of the tract architecture in this part of the Peninsula, like the Eichlers did in the 1950's. There are many apartment buildings and townhouses that were built in this style in Mountain View, we owned such a townhouse prior to buying this house, and liked the style so much that we decided to buy another one.
After the "as-built" plans were done, we worked with Forrest to scope the project and define exactly what we wanted. Needless to say, as the planning developed, various odds and ends fell out and a couple of items came in. We have three Hunter ceiling fans that we decided to remove. Ceiling fans are about the worst form of cooling around. They generate more heat than they remove. If you stand right under them, they do generate some cooling but for that they heat up the air around the motor. We never use them. The ceiling fan electrical connections in the ceiling then are freed up. In the living room and Buddha room, we'll put in light fixtures, since these rooms are dark. In the hall, we'll put in shades that are electrically driven and cover the ridge skylights at night. These skylights radiate lots of heat out of the building on cold winter nights, because they are at the highest point in the house which is where all the warm air collects. And we will put a skylight in the living room with an electric shade to increase the natural light.
These are actually minor points, though, the major point is that we plan to take off the dry wall and reinsulate the entire upstairs including all the ceilings, and about 80% of the downstairs outer walls, and fix the spreading problem by putting steel in the hall ceiling. The only exceptions are the master bedroom and bath, where we will live during the work, and the kitchen, which we had reinsulated a couple years ago. This will be a messy job, requiring scaffolding through the entire house. All the furniture must come out, and we must essentially move out into the back bedroom. Because the house will be much tighter, we need to install a Heat Recovery Ventilation (HRV) system. This takes outside air, runs it through a heat exchanger in which the inside air either heats or cools the incoming air depending on the season, and vents the fresh outside air into the building and the stale inside air out. The ventilation ensures that the inside air is always fresh and the heat recovery function ensures that heating or cooling energy isn't wasted.
Other work includes plans to add a geothermal heat pump which will require drilling two wells in the front yard. Geothermal heat pumps are the most efficient HVAC systems around, and will give us some air conditioning in case we get more hot, muggy weeks as the climate changes, like the one we had last August. We will replace our wood pellet stove in the living room with a gas-fired fire place, 88% efficient. I really wanted a new wood pellet stove that was more automated, but Santa Clara County no longer allows wood burning appliances to be installed due to problems with severe air pollution in winter during inversions. This fireplace will work when the electricity is out (but not of course the gas) and though it will not get us to full net zero energy, we will buy carbon offsets for it. Yes, I know, they are like indulgences during the Middle Ages but we still have a gas cooking stove which we don't plan to replace because cooking with gas is much nicer than with electricity. Maybe some day they'll have biogas or someone will come out with a wood stove that doesn't let off any air pollution.
We will also replace our gas backup tank water heater with an on-demand electric water heater to supplement the solar. We decided on an electric backup because we can install solar PV to offset the electricity. We decided on an on-demand heater rather than use the second heat exchanger in the solar tank or an electric coil because any heater that was connected to the solar tank would not take full advantage of solar energy. If you set the tank temperature to 120F, then the electricity will always come on to keep the temperature at that point, even if it is in the middle of the night. With an on-demand heater, the solar collector has an opportunity to add energy during the day, and the on-demand heater only comes on to top off the temperature to 120F when there is demand. So it should use much less electricity, though it will probably be more expensive initially. And it will require that we install a 200 amp electric service from the grid, but we were planning on doing that anyway, since we wanted the extra capacity for the geothermal and maybe another electric car - someday, when our budget recovers from this project.
Finally, we plan on adding more solar PV so that we can offset the geothermal heat pump, the electric hot water heater, and also generate some solar to offset the gas (in addition to the offsets bought from PG&E). Right now, we're looking at a 4 kw system total, but it may go up since there is now no downside to installing as much solar capacity as your pocktbook and roof resource allows. Starting next year, PG&E will pay you back for any extra power you generate above what you use (YAAH!). Over the last 6 years, we've consistently given PG&E something like $70-180 a year back because we've generated more power than we've used, primarily because we've done a lot to reduce our consumption (our solar PV system is actually not very large). This year we gave back much less because of the plug-in hybrid car and the new solar thermal hot water system, which uses a pump.
We're now at the point where we have a preliminary budget (around $200K - expensive!) and are beginning to work on plans to move the furniture out. Forrest is going to start the design of the geothermal system, and we still need to make a few additional decisions. It's going to be pretty disruptive but when we're done, the house will be a lot tighter, more like modern houses, and we should have around 90% of the carbon footprint eliminated (100% if you include offsets). Stay tuned!
We decided to think about what more we could do that would move our house closer to our goal of net zero energy. The experience with getting bids on the ceiling showed us that we were about at the limit of what we could do by attacking the problem piecemeal. Most contractors are clueless about how to do good insulation. When we had the kitchen ceiling redone a couple years ago to get rid of leaky can lights, I had to walk the contractor through what he needed to do to get a tight seal, though he is otherwise quite competent and is the most accurate in doing bids that I have found. We decided to work with an architectural firm that has lots of experience with green architecture, Vox Design in downtown Mountain View. Vox is run by Randy Potter and Forrest Linebarger. I know Randy from my time on the Mountain View Sustainability Task Force, we ended up working with Forrest because he had the most time. We've had four meetings with Forrest since Christmas and are getting close to finalizing the design.
The first order of business before Christmas was to get an "as-built" CAD model of the house, since we had no plans. One Saturday, a guy came over and measured the whole house, checked out all the various kinds of surface (hardwood floor, etc.). Our house has a lot of odd corners here and there, many of the walls don't exactly line up as you might expect, so he had some difficulty getting an accurate plan. This is somewhat of an architectural feature, not a function of sagging over time or anything like that. The house is in a style called "Sea Ranch" after a development along the Mendocino Coast that was built in the 1970's and influenced a lot of the tract architecture in this part of the Peninsula, like the Eichlers did in the 1950's. There are many apartment buildings and townhouses that were built in this style in Mountain View, we owned such a townhouse prior to buying this house, and liked the style so much that we decided to buy another one.
After the "as-built" plans were done, we worked with Forrest to scope the project and define exactly what we wanted. Needless to say, as the planning developed, various odds and ends fell out and a couple of items came in. We have three Hunter ceiling fans that we decided to remove. Ceiling fans are about the worst form of cooling around. They generate more heat than they remove. If you stand right under them, they do generate some cooling but for that they heat up the air around the motor. We never use them. The ceiling fan electrical connections in the ceiling then are freed up. In the living room and Buddha room, we'll put in light fixtures, since these rooms are dark. In the hall, we'll put in shades that are electrically driven and cover the ridge skylights at night. These skylights radiate lots of heat out of the building on cold winter nights, because they are at the highest point in the house which is where all the warm air collects. And we will put a skylight in the living room with an electric shade to increase the natural light.
These are actually minor points, though, the major point is that we plan to take off the dry wall and reinsulate the entire upstairs including all the ceilings, and about 80% of the downstairs outer walls, and fix the spreading problem by putting steel in the hall ceiling. The only exceptions are the master bedroom and bath, where we will live during the work, and the kitchen, which we had reinsulated a couple years ago. This will be a messy job, requiring scaffolding through the entire house. All the furniture must come out, and we must essentially move out into the back bedroom. Because the house will be much tighter, we need to install a Heat Recovery Ventilation (HRV) system. This takes outside air, runs it through a heat exchanger in which the inside air either heats or cools the incoming air depending on the season, and vents the fresh outside air into the building and the stale inside air out. The ventilation ensures that the inside air is always fresh and the heat recovery function ensures that heating or cooling energy isn't wasted.
Other work includes plans to add a geothermal heat pump which will require drilling two wells in the front yard. Geothermal heat pumps are the most efficient HVAC systems around, and will give us some air conditioning in case we get more hot, muggy weeks as the climate changes, like the one we had last August. We will replace our wood pellet stove in the living room with a gas-fired fire place, 88% efficient. I really wanted a new wood pellet stove that was more automated, but Santa Clara County no longer allows wood burning appliances to be installed due to problems with severe air pollution in winter during inversions. This fireplace will work when the electricity is out (but not of course the gas) and though it will not get us to full net zero energy, we will buy carbon offsets for it. Yes, I know, they are like indulgences during the Middle Ages but we still have a gas cooking stove which we don't plan to replace because cooking with gas is much nicer than with electricity. Maybe some day they'll have biogas or someone will come out with a wood stove that doesn't let off any air pollution.
We will also replace our gas backup tank water heater with an on-demand electric water heater to supplement the solar. We decided on an electric backup because we can install solar PV to offset the electricity. We decided on an on-demand heater rather than use the second heat exchanger in the solar tank or an electric coil because any heater that was connected to the solar tank would not take full advantage of solar energy. If you set the tank temperature to 120F, then the electricity will always come on to keep the temperature at that point, even if it is in the middle of the night. With an on-demand heater, the solar collector has an opportunity to add energy during the day, and the on-demand heater only comes on to top off the temperature to 120F when there is demand. So it should use much less electricity, though it will probably be more expensive initially. And it will require that we install a 200 amp electric service from the grid, but we were planning on doing that anyway, since we wanted the extra capacity for the geothermal and maybe another electric car - someday, when our budget recovers from this project.
Finally, we plan on adding more solar PV so that we can offset the geothermal heat pump, the electric hot water heater, and also generate some solar to offset the gas (in addition to the offsets bought from PG&E). Right now, we're looking at a 4 kw system total, but it may go up since there is now no downside to installing as much solar capacity as your pocktbook and roof resource allows. Starting next year, PG&E will pay you back for any extra power you generate above what you use (YAAH!). Over the last 6 years, we've consistently given PG&E something like $70-180 a year back because we've generated more power than we've used, primarily because we've done a lot to reduce our consumption (our solar PV system is actually not very large). This year we gave back much less because of the plug-in hybrid car and the new solar thermal hot water system, which uses a pump.
We're now at the point where we have a preliminary budget (around $200K - expensive!) and are beginning to work on plans to move the furniture out. Forrest is going to start the design of the geothermal system, and we still need to make a few additional decisions. It's going to be pretty disruptive but when we're done, the house will be a lot tighter, more like modern houses, and we should have around 90% of the carbon footprint eliminated (100% if you include offsets). Stay tuned!
Wednesday, February 17, 2010
The Electric Car Resurrection I: Some Background
If 2003 was the year when GM killed the electric car, then 2010 is shaping up to be the year when it is resurrected. Nissan is currently firming up plans to sell the Leaf by year's end. GM is on track to release the Volt (not an all electric but close). Tesla has had their Roadster out for a couple years now, and recently I actually spotted one on 237 while driving to work in the morning. Then there are the smaller players, like the Fisker Karma, a plug-in hybrid like the Volt but more expensive, and the Chinese manufacturer BYD that is backed by Warren Buffet. Is the electric car now about to go mainstream and solve our problems with Mideast oil, carbon generation, and pollution?
After seeing the documentary film "Who Killed the Electric Car?" in 2006, I decided to look into what it would take to get an electric car. At that time, there were exactly zero commercially available electric cars, not even at the $109,000 price of the Tesla. So the only alternative was to convert an existing ICE powered vehicle to electric. I spent about two years researching what that would take.
My first stop was Electroautomotive, a company in nearby Felton that has been doing conversions and offering conversion kits since the energy crisis of the '70's. I attended a one day workshop on conversions held by Electroautomotive in Silicon Valley. I found out that the technology for hobbist conversions basically had also changed little since the 1970's. They were recommending a 80 volt DC system with flooded lead acid batteries. My 2002 Prius has a 274 volt NiMH battery pack and AC traction system. The range for one of their conversions varied depending on the weight of the coverted vehicle. For maximum range, they were recommeding using a 10 year old Geo Metro, since the weight is under 1500 lbs, or a light weight pickup truck, also preferably 10 years old, and then filling the back with batteries. Cost would probably have run around $8K-$12K depending on batteries and components, and, of course, I would have had to do the conversion work myself, no small problem since I am by and large hopeless with tools more complicated than a screwdriver.
The problem with converting a 10 year old car to electric is ... you end up with a 10 year old car (dents, cracked plastic from aging, no airbags or antilock breaks, stained upholstery) that goes maybe 100 miles if you are lucky. I looked into converting a new car, but there were only three cars on the market that were at or under 1500 lbs - the Toyota Yaris, the Honda Fit, and the Chevy Aveo. These are tiny cars with very little room for batteries. Given the minimum amount of room, the range would probably have been less than 100 miles.
Then there are the batteries. Lead acid batteries only last around 3 years when used as traction batteries in electric cars. Even though they are cheap (maybe around $800 for a full set) and they are up to 99% recycled, they are still heavy and having to swap out the batteries every 3 years is a major inconvenience. Flooded batteries were recommended for automotive traction applications because they have the best power output, but they are notoriously fickle and require checking periodically to be sure the plates aren't drying out. Sealed batteries require less maintenance but they don't provide enough range.
While I might have been able to live with having an expensive 10 year old car, the range was the show stopper. I wanted at least 120 miles so I could comfortably drive up to San Francisco and back without recharging (not of course that I do such a drive often, but I at least wanted to be able to do it in principle). So the next thing I looked into was lithium batteries. In principle, I would have been able to get the range I wanted, but the cost would have been prohibitive, around $20,000 just for the batteries. At the time, there was only one company that was selling prismatic lithium ion batteries appropriately large enough for such applications, Thunder Sky in China. Lithium ion batteries require a different kind of charging system and are much more sensitive to overcharging and extreme draw down than lead acid batteries.
I then turned to the local Electric Autombile Association and attended one of their meetings to find out whether anyone had experience with lithium batteries. The meeting was interesting, the featured speaker described an electric motorcycle for racing in which he attempted to clinch the world land speed record for 2 wheeled vehicles (I think he succeeded in the interim). His strategy was to essentially draw down the lithium batteries so fast that they were essentially ruined after one run, then to swap them out for the next. Not a strategy that would work for my vehicle, however.
After asking around, I got some warnings about Thunder Sky batteries, that the quality was variable. Someone said they had bought a bunch and some had turned out to run down after only a few charge/discharge cycles. Left unsaid, however, was whether the battery chemistry was safe for vehicular applications. I don't know what chemistry Thunder Sky used, but the battery chemistry used for laptop and cell phone batteries is completely inappropriate for vehicular applications without lots of additional engineering. Tesla, for example, spent years designing an explosion control cabinet to contain any of the thousands of laptop battery cells they use in the Roadster from igniting the others should a cell catch on fire. If Thunder Sky used the same chemistry as used in laptop batteries, an electric car with those batteries would have been a dangerous hazard should an accident occur.
I also finally got real about my ability to do the conversion work. Realistically, even if I got a membership at Tech Shop, there was no way I would have the time nor the motiviation to pursue the project to completion. I asked around at the Electric Automobile Association whether anybody knew of a place that would do a conversion. There was a guy there who said he would do one, we took up an email correspondence but it turned up he was really interested in selling electric scooters and the correspondence was just talk. I searched the Internet a bit. The Internet search turned up one guy in LA who had been doing conversions, but he had since stopped. There were some conversions for sale in San Francisco, a Toyota Yaris if I recall correctly, but the range was under 100 miles.
In the spring of 2008, I was just about to give up in despair when A123 Systems announced their L5 modules for turning a 2004-2008 Prius into a plug-in hybrid. And that is the subject for another post.
After seeing the documentary film "Who Killed the Electric Car?" in 2006, I decided to look into what it would take to get an electric car. At that time, there were exactly zero commercially available electric cars, not even at the $109,000 price of the Tesla. So the only alternative was to convert an existing ICE powered vehicle to electric. I spent about two years researching what that would take.
My first stop was Electroautomotive, a company in nearby Felton that has been doing conversions and offering conversion kits since the energy crisis of the '70's. I attended a one day workshop on conversions held by Electroautomotive in Silicon Valley. I found out that the technology for hobbist conversions basically had also changed little since the 1970's. They were recommending a 80 volt DC system with flooded lead acid batteries. My 2002 Prius has a 274 volt NiMH battery pack and AC traction system. The range for one of their conversions varied depending on the weight of the coverted vehicle. For maximum range, they were recommeding using a 10 year old Geo Metro, since the weight is under 1500 lbs, or a light weight pickup truck, also preferably 10 years old, and then filling the back with batteries. Cost would probably have run around $8K-$12K depending on batteries and components, and, of course, I would have had to do the conversion work myself, no small problem since I am by and large hopeless with tools more complicated than a screwdriver.
The problem with converting a 10 year old car to electric is ... you end up with a 10 year old car (dents, cracked plastic from aging, no airbags or antilock breaks, stained upholstery) that goes maybe 100 miles if you are lucky. I looked into converting a new car, but there were only three cars on the market that were at or under 1500 lbs - the Toyota Yaris, the Honda Fit, and the Chevy Aveo. These are tiny cars with very little room for batteries. Given the minimum amount of room, the range would probably have been less than 100 miles.
Then there are the batteries. Lead acid batteries only last around 3 years when used as traction batteries in electric cars. Even though they are cheap (maybe around $800 for a full set) and they are up to 99% recycled, they are still heavy and having to swap out the batteries every 3 years is a major inconvenience. Flooded batteries were recommended for automotive traction applications because they have the best power output, but they are notoriously fickle and require checking periodically to be sure the plates aren't drying out. Sealed batteries require less maintenance but they don't provide enough range.
While I might have been able to live with having an expensive 10 year old car, the range was the show stopper. I wanted at least 120 miles so I could comfortably drive up to San Francisco and back without recharging (not of course that I do such a drive often, but I at least wanted to be able to do it in principle). So the next thing I looked into was lithium batteries. In principle, I would have been able to get the range I wanted, but the cost would have been prohibitive, around $20,000 just for the batteries. At the time, there was only one company that was selling prismatic lithium ion batteries appropriately large enough for such applications, Thunder Sky in China. Lithium ion batteries require a different kind of charging system and are much more sensitive to overcharging and extreme draw down than lead acid batteries.
I then turned to the local Electric Autombile Association and attended one of their meetings to find out whether anyone had experience with lithium batteries. The meeting was interesting, the featured speaker described an electric motorcycle for racing in which he attempted to clinch the world land speed record for 2 wheeled vehicles (I think he succeeded in the interim). His strategy was to essentially draw down the lithium batteries so fast that they were essentially ruined after one run, then to swap them out for the next. Not a strategy that would work for my vehicle, however.
After asking around, I got some warnings about Thunder Sky batteries, that the quality was variable. Someone said they had bought a bunch and some had turned out to run down after only a few charge/discharge cycles. Left unsaid, however, was whether the battery chemistry was safe for vehicular applications. I don't know what chemistry Thunder Sky used, but the battery chemistry used for laptop and cell phone batteries is completely inappropriate for vehicular applications without lots of additional engineering. Tesla, for example, spent years designing an explosion control cabinet to contain any of the thousands of laptop battery cells they use in the Roadster from igniting the others should a cell catch on fire. If Thunder Sky used the same chemistry as used in laptop batteries, an electric car with those batteries would have been a dangerous hazard should an accident occur.
I also finally got real about my ability to do the conversion work. Realistically, even if I got a membership at Tech Shop, there was no way I would have the time nor the motiviation to pursue the project to completion. I asked around at the Electric Automobile Association whether anybody knew of a place that would do a conversion. There was a guy there who said he would do one, we took up an email correspondence but it turned up he was really interested in selling electric scooters and the correspondence was just talk. I searched the Internet a bit. The Internet search turned up one guy in LA who had been doing conversions, but he had since stopped. There were some conversions for sale in San Francisco, a Toyota Yaris if I recall correctly, but the range was under 100 miles.
In the spring of 2008, I was just about to give up in despair when A123 Systems announced their L5 modules for turning a 2004-2008 Prius into a plug-in hybrid. And that is the subject for another post.
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