12V chemistry isn't really a solved issue, but it's a necessity. The problem with substituting it with anything else is that nothing can endure high and low temperatures like lead acid. It's regularly 70C/160F under the hood of a car, and a car should still start up at -20C/0F. Especially if you also need to be able to supply cranking amps, the only solution that is even remotely available is lead acid.
Almost all replacements have severe limitations. For instance, a capacity-equivalent LFP equivalent can't supply cranking amps over its temperature range and is limited to +55C storage/+45C operational. Cost-equivalent LFP isn't even close to large enough for even an EV and its idle loads.
Most other chemistries aren't voltage compatible. Most li-ion in 3S configurations has a top voltage that's too low (12.6V), most other alkaline rechargeables also aren't quite compatible with the ~14.4V charge voltag eand ~10.6V low-voltage cutoff. LFP 4S will survive but is still beaten during bulk charge (to fix that it needs a bleed-off circuit, or you have to be happy to lose cycles).
Rock and a hard place.
At least an EV doesn't pull as many amps, so LFP is an option, but it's still very expensive for the capacity and not quite a drop-in replacement.
Proper solutions to all of this exist and have for decades, but nobody's even attempting to use them. The best we've got now is always-on dc/dc converters, which are extremely wasteful and make the cars more dangerous to work on.
Almost all replacements have severe limitations. For instance, a capacity-equivalent LFP equivalent can't supply cranking amps over its temperature range and is limited to +55C storage/+45C operational. Cost-equivalent LFP isn't even close to large enough for even an EV and its idle loads.
Most other chemistries aren't voltage compatible. Most li-ion in 3S configurations has a top voltage that's too low (12.6V), most other alkaline rechargeables also aren't quite compatible with the ~14.4V charge voltag eand ~10.6V low-voltage cutoff. LFP 4S will survive but is still beaten during bulk charge (to fix that it needs a bleed-off circuit, or you have to be happy to lose cycles).
Rock and a hard place.
At least an EV doesn't pull as many amps, so LFP is an option, but it's still very expensive for the capacity and not quite a drop-in replacement.
Proper solutions to all of this exist and have for decades, but nobody's even attempting to use them. The best we've got now is always-on dc/dc converters, which are extremely wasteful and make the cars more dangerous to work on.
