Thread: Charging Batteries in Parallel

I normally leave my deep cycle in the trailer hooked up to a Projecta staged charger to keep it topped up (was advised to do this by a battery supplier). Thinking of adding another deep cycle in parallel to give me a longer life when in the bush. I read a thread not so long ago where Drivesafe said that this was an ok thing to do and wouldn't compromise either battery (I think most on here take his word on auto elecs and DC power as gospel).
My question is, when I hook up the charger to one of the batteries in parallel, will it charge them both (and importantly keep them both charged)?

Hi Folks, and wardy1, I hope people don’t just take my word as gospel and go and check to see if I have got it right.

As dswatts posted, once you connect batteries in parallel, you get one bigger battery.

Hi bbarkz, a bit of a misunderstanding there, many battery manufacturers recommend this 10% charging but it’s not the MINIMUM current required but what the manufacturer sees as the OPTIMUM charge current.

Any lower and it will take ( by there view ) an unacceptably longer time to fully charge the battery and any higher and you start to have a detrimental effect on the life span of the battery.

In both cases of going lower or higher, there are limits but you need the exact data relating to a specific brand of battery as supplied by that battery’s manufacturer.

I have a number of 200 Ah Exide batteries and use nothing bigger than a 7 amp multi stage charger because I want to extend their operating life as far as I can but I also have the time between uses to be able to do a slow re-charge ( this helps make up for the abuse I give them during high current discharges )

Hi bee utey, with the exception of hi tech batteries like Lithium Iron Phosphate batteries ( I know very little about these ) all automotive batteries are actually of the same chemistry, lead acid. The lead acid electrolyte is just stored in different ways but they are still the same and can be paralleled together.