Originally Posted by Scalf77
AGM batteries will suffer from Peukert’s Law while discharging heavy loads, Li does not suffer the same.
Both systems will still see some voltage drop based on your wire size and length.
I agree, but excuse me if I add a little clarification.
The original point was about voltage sag at high discharge rates. The ideal battery voltage model has an internal resistance (IR) parameter that is relatively much higher for LA vs LiFePO4 and most all Li.
LA IR varies with SOC but is generally above 20 mOhms(see link below). In contrast, LiFePO4 IR is typically sub 1 mOhms (EVE 280 Amp-Hr are typically 0.13 mOhms).
This is really what makes LI dangerous because whereas LA is somewhat sell limiting with >20 mOhms (it is still can act like a welder) the resistance of LI is 1/100th of that. The short itself is the only thing to limit the current.
>>>AGM and LI are pretty different. I am not sure if AGM sufferes a voltage sag during heavy discharge. I don't think that is the case with LI.
So I think what is going to be easy to observe is that for LA the voltage drops at for example an inverter is going to be a combination of the LA internal resistance and the cable losses regardless of capacity or changes in capacity (e.g. Peukert's Effect).
For LiFePO4 the discharge is characteristically very flat with SOC but in addition, the internal resistance is probably < 1/100 of LA so the voltage drops are going to largely only those of the cables and connections.