Question: Caravan & Camper Battery Charging

We have a similar dual battery system set up.

My question is system: can I charge the aux battery with solar panels and the dual battery system simultaneously without damaging the battery or something else?

If two separate charing sources are going into the battery at the same time will the redarc "know" when the battery is full and not over charge it? Also will the solar panel regulator "know" when to stop charging?

Or would it be just better to have a switch to turn on/off the solar charging source once the vehicle has stopped running separating the charging mechanisms?

I've ask a few auto sparkies and 240 volt sparkies with no definitive answer. Also nobody I know has done it. I'd love to your feed back and especially from anyone who has done it.

Would also love to hear about alternative charging methods that don't make sound i.e. genset.


Pat and Cecilia
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Reply By: Bigfish - Sunday, Sep 04, 2011 at 06:58

Sunday, Sep 04, 2011 at 06:58
Have had 3 large solar panels connected to my roof rack and feeding 4 large batteries in the vehicle for a long time. Have a redarc also fitted. This arrangement has worked well for years and no battery problems whatsoever. The solars are connected to the auxillaries. The car alternator charges the main battery and then if reqd the aux. Leave the solar panel on at all times, it wont hurt. Make sure it is connected to the aux battery though, as your main battery really should be isolated for starting your vehicle and low power vehicle additions. Once fully charged from your alternator the redarc will automatically direct charge to your aux battery. If you do intend to stop at one place for a while, you can connect your main battery to the solar if you just want trickle charge it to keep it fully charged. The redarc battery isolater IMHO is a great product and a good solar regulator will also take care of the voltage/amps heading into your batteries.
They really are simple setups.
AnswerID: 464156

Follow Up By: Member - Kevin S (QLD) - Sunday, Sep 04, 2011 at 08:18

Sunday, Sep 04, 2011 at 08:18
Redarc now have a charger that will take solar panel input and protect the starter battery as well.
It is important to always maintain a sense of proportion

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FollowupID: 738061

Reply By: Battery Value Pty Ltd - Sunday, Sep 04, 2011 at 09:25

Sunday, Sep 04, 2011 at 09:25
Hi filosoph,

in a typical dual battery setup (with isolation switch/solenoid), solar energy can't be absorbed by the aux battery while it's being charged by the alternator (the solar current would just reduce the alternator current proportionally, but the sum of the two will stay the same).
So there's nothing to be gained during cruising, in terms of higher charging amps.
Different story of course when stationary.
Now the starter battery/alternator is electrically isolated from the aux, no need to put in an additional switch to prevent solar current from entering the starter battery.
And no, you can't do any damage to any components if you permanently wire the solar regulator to the aux battery.
In fact, this is what we recommend to our battery/solar customers.
But be aware that the solar regulator draws a small current, so if the system is left sitting around for months with no solar input, the aux gets drained slowly - so in this case you might want to pull the fuse in the positive leg to the aux battery.

cheers, Peter
AnswerID: 464165

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