> For example, a Chevy Bolt has a lithium ion battery to power the drivetrain and a conventional lead-acid battery for the accessories.
This seems like an odd choice - unless you already bought a supply of lead-acid batteries for the next 50 years or so.
I've read about a car using supercapacitors in the regenerative brakes to capture energy at high current and, then let it trickle back into the main batteries (or drivetrain) at levels that won't damage it.
That was a bit of a necessity. Users wouldn’t want their clock to reset when they swapped batteries, and you couldn’t be sure the machine was connected to a time server to set the time at boot.
It could be great if you were a car manufacturer that already had an existing, very large supply chain for lights, dashboard, powered window motors, and other accessories, that were already 12 volt.
Tesla switched from lead-acid to 12V lithium ion their S and X models in 2021. James May had some issues with his Tesla when the 12V battery went flat.
This was the best news I heard at Tesla investor day. It should simplify and cut the cost of the in-cabin wiring.
When Sandy Munro interviewed Elon Musk a couple of years ago he said "Why are you still using 12v stuff in the cabin?"
Musk's answer was that the automotive supply chain was entirely geared around 12v equipment and they had to take advantage of that to get to market quickly.
The supercaps aren't for long-term storage - just long enough to allow the extra juice to flow back to the batteries. Racing cars sometimes do that with flywheels.
As for 12V, all one needs is a regulator. Unless you have a long-term supply contract (that, I bet, won't be renewed for too long), a lead-acid battery is just dead weight.
This seems like an odd choice - unless you already bought a supply of lead-acid batteries for the next 50 years or so.
I've read about a car using supercapacitors in the regenerative brakes to capture energy at high current and, then let it trickle back into the main batteries (or drivetrain) at levels that won't damage it.