[RRRA]

Most new solar installations now use LiFePO4 which apparently is much safer on that runaway side...

[sorenjan]

That's good, but is that what's used in "used car-batteries with degraded capacity"?

[samtho]

Used car batteries are conventional unsealed, lead-acid batteries. Lithium-iron-phosphate (aka LiFePO4, LFP) batteries is a different battery chemistry altogether. It is touted as the answer to a deep-cycle, lithium-based electrical storage that the traditional lead acid batteries occupy.

[BirAdam]

Also way better cycle life, but the density is slightly lower.