Parallel battery charging + solar

mike w

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Sorry to post yet another solar question, I have tried to search for the answer, but got nowhere.
My plan is to install solar, looking like a 140 watt panel with a MPPT controller charging two 12 volt leisure batteries (in parallel) of different capacities. As a newbie I am stumped on a couple of questions.
Will a standard single battery controller handle two batteries in parallel without causing long term damage?
Should I look at a two battery controller and isolate the two using some form of diode pack?
I have no requirement to charge the vehicle battery with this set up.

My original bare bones set up has been the use of two isolater switches. This set up allowed me to introduce a jumper battery when required and to charge independently when driving.

Thanks in advance for replies and ideas.
 
You mention batteries of different capacities in parallel.

Don’t they need to be the same capacity else the larger battery will never fully charge?

It will only charge to the level of the value of the lowest capacity battery but I may be right or wrong on this.

Worth checking out but I thought parallel batteries had to all be the same size to maximise battery charge levels and to avoid voltage imbalance issues as they discharge.
 
They've been working ok so no reason they shouldn't carry on doing so the 2 odd batterys isn't the best but can be corrected when they need changing. Just connect up the solar and your done.
I use this method to charge engine battery when vans parked up
 
You need to make sure the inter battery cables are at least as large as the others, I also would connect the incomeing and outgoing power across both batteries to help balance the loads, IE connect the controller to the + on one and the - on the other, use the opposite terminals for the power out such as an inverter.
 
Thanks for the comments guys, researching this further it appears to be a no no charging and discharging two batteries of different capacities.
Looking on Wildebus's website he has a product Cyrix-CT that acts as battery combiner for split charging. Looks like this is the product I need, however its not suitable with "Smart Alternators"
Would a 2008 X250 Boxer have this fitted?
 
When wiring two batteries together it’s much better if they are the same size, and if possible the same age. Using batteries with different capacities and of varying age, puts limitations on what you are doing.
 
On any battery operated item it says do not use different batteries, when you look it up it states that the better battery will deplete as it is charging the lesser battery, I assume similar happens in a MoHo.
 
Pudsey Bear said:
On any battery operated item it says do not use different batteries, when you look it up it states that the better battery will deplete as it is charging the lesser battery, I assume similar happens in a MoHo.
Click to expand...
It isn’t the same thing at all, that’s normally disposal battery’s that aren’t recharged and they can swell.

Leisure battery’s can be connected together in parallel with different ah ratings so long as they are the same voltage but not in serial. Best practice is to use same ah rating and age of battery but that doesn’t mean you can’t or shouldn’t use what you have. I would be more worried connecting different technology of battery’s together than different capacity’s and we have a few who do that with no problems at all, in fact with good results (hybrid systems).

In parallel connection it is seen as one large battery for charging and discharging.

Edit: some makes/models of battery have limitations so always bear that in mind. Don’t connect three when it says no more than two, that sort of thing
 
Nabsim said:
It isn’t the same thing at all, that’s normally disposal battery’s that aren’t recharged and they can swell.

Leisure battery’s can be connected together in parallel with different ah ratings so long as they are the same voltage but not in serial. Best practice is to use same ah rating and age of battery but that doesn’t mean you can’t or shouldn’t use what you have. I would be more worried connecting different technology of battery’s together than different capacity’s and we have a few who do that with no problems at all, in fact with good results (hybrid systems).

In parallel connection it is seen as one large battery for charging and discharging.

Edit: some makes/models of battery have limitations so always bear that in mind. Don’t connect three when it says no more than two, that sort of thing
Click to expand...
Glad I said I assume :D :D
 
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