Thread: Triple Battery System

Hi austastar, the figure I’m going to use are examples ONLY. There are too many variables to give exact info but you will get the idea.

If your alternator is putting out say 13.5v and you have one 100 Ah flooded wet cell deep cycle battery ( I use these as the example battery because they are the slowest to charge ) and during normal use, you discharge it down to 40% SoC, you will need about 5 hours driving time to fully charge the battery.

You will raise the battery to about 85-90% in the first 3 hours and then it will take about 2 hours to fully charge the battery.

If you have two 100 Ah batteries and use the same amount of power, each battery will only be discharged down to 70% SoC.

So when you start driving, you will raise the two batteries to 85-90% in a little over an hour and then again another two hours to fully charge them.

That’s the basics but there are heaps of other advantages to running larger battery set ups than you would normally think is required.

One obvious benefit is the fact that if you need more power, you already have it but even just using the same amount of power you would normally do when using a single battery, with a two battery set up, because you are spreading the load over two batteries, you are halving the constant current load on both batteries and this in itself is a plus for extending the operating life span of any battery.

The fact you are not taking the two battery set up as low as a single battery set up, again you are helping extend the operating life span.

There are other benefits but also note, if your alternator voltage is higher, the recharge times will be even shorter.