Batteries

Without getting too technical let’s take our situation which is a caravan that has

3 x 12 volt AGM Deep cycle batteries. Each battery is 120ah (amp hour).

The key to the batteries is the ah reading. Ah is short for Amp hours so for simplicity reasons 100ah battery means you can use 1 amp of electricity from that battery for 100 hours before the battery is totally and utterly flat. Connecting batteries in series doubles the voltage but keeps the amp hours the same, connecting batteries in parallel maintains the voltage and increases the amp hours, refer google if you want to know more but in terms of caravans you’ll generally be connecting batteries in parallel.

Click Icon to download the Solar/Battery calculator spreadsheet

Caravan’s use AGM deep cycle batteries (or better like the recent Lithium 12 volt batteries). They do not use the standard lead acid starter batteries that you use in your car. There’s a reason for this that I won’t explain here but for now just be aware that there is a difference.

Having 3 x 120ah batteries connected in parallel gives us a total of 360ah of current we could use however.... deep cycle batteries do NOT like to go less than %50 charge or else the life expectancy of the battery drops hugely (there’s a chemical reason for that which I won’t go into either but feel free to read the battery university website if your curious) therefore our 360ah battery system is effectively 180ah "useable" amps. Which means in one day if we used 180amps of electricity our batteries would be %50 flat and that’s as low as we want them to ever be, that equals 7.5amps per hour usage.

Like everything its up to the individual to decide whats right for your needs. To help guide you in your decision try entering different battery AH ratings in the below excel spreadsheet and see what results you get.