20A vs 45A

Not necessarily. The stuff has improved a lot, we now have high drain and high capacity in ways which were not possible years ago.

However, the way continuous drain rates (without temperature limits) are defined certainly pose certain restrictions to the maximum allowable energy in a cell because if not, its temperature would raise sky high without adequate cooling.

That is completely inadequate for li-ion cells. Also, cold cranking amps is as misleading as measuring an engine's pull ability by means of its torque, this is because what makes work or pull is power. And power is V × A, or rotational speed times torque.

If I am to design a LiFePO4 car battery given the continuous ratings of its cells, by the same CCA rating it would certainly leave the lead-acid battery in the dust¹. This is because for the same amount of amperage the LiFePO4 battery would output higher voltage, or more amperage for the heavily depressed voltage the CCA rating is defined, which means more power.

¹ Except in very cold conditions, it is said.

made you think, though :slight_smile:

wle