What “repairs” are in order for a battery?
The only thing that comes to mind is cleaning corrosion on the terminals (that is increasing electrical resistance).
If corrosion is on the negative terminals, that indicates undercharging. On he positive, overcharging.
These big batteries are huge assemblies of small lithium cells. Individual cells can go bad, and that compromises the entire battery. When I was flying RC airplanes at the dawn of lithium technology it wasn’t uncommon to have dismantle a pack to replace a cell, but those batteries were usually only three or four cells. It’s different when there’s a thousand of the little buggers.
Moving to computers - I used to collect “failed” Dell C and D series loptop batteries from our IT guy. He loved that because otherwise he had to fill out haz-mat paperwork to dispose of them. I took them apart to salvage the 18650 cells. As often as not, what had actually failed was the charge management board. All individual cells took and delivered charge just fine. I used them in the airplanes. I don’t fly anymore, but I still have several dozen of them around. Can you replace the charge management electronics in a Tesla battery? Don’t know. But if I were facing $20,000 for a replacement I’d sure look into it.
My airplane packs were air cooled, but these car batteries have to have an active cooling system, (I assume some sort of liquid is pumped through the matrix.) So there’s another point of failure that might be repaired if you knew how and had the tools.
Needless to say, what with the voltages and short-circuit current capacities of these big EV batteries, they are a bomb waiting to go off the moment you open them up.
Interesting...
.
If All the Cells were ‘D’ sized batteries
Standardized replacement would be less
Intimidating.
>> What “repairs” are in order for a battery?
Most Li batteries are comprised of a number of standard “cells” like 18650. They’re joined togther in some series-parallel combination to achieve the required voltage and ampacity. The “wiring” is typically flat stainless steel ribbons that are spot-welded to each individual cell.
Those are facts, what follows is speculation.
One form of repair might involve finding and replacing individual “bad” cells.
Another form of repair might be salvaging “good” cells from “bad” batteries and connecting them to form a “good” battery.
None of this would be easy, straightforward, or cheap, methinks.