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I did consider LiFePo4 batteries, but Getting them to Europe is expensive, there is no European reseller of the sizes relevant here. Studying Li-Ion batteries, it dawned on me that undercharging them increase cycle life to 2000-4000 range and they become a safe as LiFePo4 batteries as you never drive them near the the electrode decomposition voltage, so in effect you have the benefit of LiFePo4 and a capacity/weight around LiFePo. What I did not mention is that I have a 10A LiFePo4 BMS on my pack as a secondary protection cutting off the pack if any cell goes above 3.9V or current draw is higher than 10A. I do know that this is an relative expensive system having a long payback time, but I had most of the stuff from an electric bike project. I've driven around for a week with this and it is totally reliable so far. What I also didn't mention is that when driving at night the battery lasts for 30 minutes until the voltage drops below the alternator cutout and it resumes normal operation, and there are no more savings to be had, but this is totally self managing. I have an MPGuino in my 98 Fiat, so my numbers are just the observed drop in the instant usage, during the last few days and I do understand that outrageous claims need matriculate proof, but I'm seeing the same numbers as other people un-belting and switching off stator current, The reason I have a large improvement in mileage is because this is a very mechanical efficient car (I can push the 990 pounds of it with my thumb to jogging speed in neutral on slick level asphalt) My real life city driving consumption is in the 47MPG range with traffic, but I need to run a few tanks to have a solid average, but the savings overall, including idling is around 25% city driving on the MPGuino so far.
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