Sunday, September 26, 2021

The Golden Arrow Glides Again



 Five years ago we adopted a 1983 Mazda RX-7 conversion and drove the last life out of its last lead-acid battery pack.  That 1120+ lbs of ancient technology has expired, replaced by 47 cells of lithium iron phosphate, a much safer, lighter, longer-lasting, powerful and energy dense battery.  Ruthie is a driver now, and her long afternoon of schlepping cells and drawing wiring diagonals rewarded with her first experience with a clutch.  I didn’t think it possible to buck a clutched EV, but she proved me wrong….

The first 47 cells fit perfectly in only the rear battery box, originally designed for 13 6 volt flooded lead acid batteries and also maximizing the capabilities of the carryover Curtis1231-C motor controller. We may later upgrade to a Zilla 1k controller for higher power and it’s higher-voltage range for yet more power and range, but this first installment should do fine for a while.  47 cells of 180 ah at 3.2 nominal voltage equals exactly 27 kWh, or exactly the original capacity of our 2016 Kia SOUL EV!  Never mind that there is room for 20 more cells in the now-empty front battery racks, for a total potential of 37.5 kWh!  That’s almost unheard of in a subcompact 2 seater EVen today, and would be enough battery for at least 150 miles of range!  Once more, LiFePO4 is a much longer-lived cell than the Nissan Leaf batteries that I now replace for fun and profit at www.EV-works.com

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