“RV Load Calculator 12 volt usage” This will tell you the Amp-Hour capacity needed to power your 12 volt items when not connected to Shore or Generator power. I.E. The converter is off and not charging . It is desirable to not allow a battery to discharge below a certain percentage for longer life.




You plan a trip where there will be no shore power for 12 hours.

During this time all 12 volt power will come from the battery bank.

Lights will be on for 4 hours.  A 12 volt refrigerator will also be on. (only the time the compressor is on will count)





Add a Laptop that is plugged into a 120 volt inverter .

The calculator shows the bank size recommended for different battery types.

Add the 12 volt requirments to the 120 volt inverter requirements to get the total bank size required.

In the example:  for Flooded lead Acid  50 + 36 = 86 Amp hour Bank capacity.

Note that these are minimum requirements to support the appliances when there is no source of  Shore or Generator Power.