Thor Forums

[16ACE27]

Your NAPA group 27 batteries are only about 90 AH each when new; so 3 gives you 270 AH, of which only 135 AH is usable in a FLA battery (50%).

LiFePO4 batteries come in various sizes but a common replacement is a group 29 size at 100 AH each. 2 of those will exceed what you have now in usable capacity.

Fridge starting current is not used to calculate available runtime. There are too many variables involved:

How many is a "few days"?
Ambient temperature?
Running current?
Duty cycle which depends on ambient temperature, fridge insulation, and door opening cycles.
What other loads are drawn from the battery bank?

to answer your question with any degree of accuracy.