Multiple battery charging systems

Submitted: Tuesday, Jun 19, 2012 at 18:57
ThreadID: 96372 Views:1657 Replies:3 FollowUps:6
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I have a HDJ79R cruiser with a canopy. On the roof of the canopy I have 2 x 80watt solar panels which charge 3 x 80 Amp Hr deep cycle batteries in the canopy. I run 2 Engle fridges off these batteries and the system works fine. The problem is when I put my boat onto the roof it covers up the solar panels and needles to say they don't charge I have installed a RED ARK battery isolator which feeds thes batteries also. I notice that here is an increase in the power and the voltage rises when the RED ARK is working. What I Would like to know is whether this system will be enough to keep these batteries charged whilst I am driving with the boat covering the panels and the fridges running.
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Reply By: ABR - SIDEWINDER - Tuesday, Jun 19, 2012 at 19:41

Tuesday, Jun 19, 2012 at 19:41
Hi Grant

Simple answer yes, most people have isolators and no solar and have no problem.


AnswerID: 488943

Follow Up By: Grant W - Tuesday, Jun 19, 2012 at 20:17

Tuesday, Jun 19, 2012 at 20:17
Thats reassuring, I just was not sure as to whether the alternator would put enough power into three batteries or it would be too much for it. Cheers
FollowupID: 764101

Follow Up By: ABR - SIDEWINDER - Tuesday, Jun 19, 2012 at 21:02

Tuesday, Jun 19, 2012 at 21:02
The fridges will draw a max of 4 amps and the alternator will provide this + more, don't worry about the alternator supplying too much as the batteries will only draw what they need. Your batteries will be fully charged when you stop.

FollowupID: 764106

Reply By: Member - Phil G (SA) - Wednesday, Jun 20, 2012 at 08:59

Wednesday, Jun 20, 2012 at 08:59
I have the same vehicle and also run 2 engels. I can run both fridges off just one 80Ah auxillary battery, as long as I'm driving about 2 hours a day. But a lot depends on ambient temperature - in the tropics, you'd need twice as much capacity than what I'd use on teh average desert trip.

The alternator is 110 amp - a good 80Ah battery will take at least 30amps if needed from the alternator provided the wiring is big enough. Just wondering what sizeRedarc isolator you're using. The smaller one would struggle if your 3 batteries have been run down a bit.

What gauge wire are you using and how are the canopy batteries earthed?
AnswerID: 489001

Follow Up By: Grant W - Wednesday, Jun 20, 2012 at 16:47

Wednesday, Jun 20, 2012 at 16:47
Thanks very much Phill, From what I recall the isolator is a SBI 12 (100 amp model), the batteries are earthed back to the main car battery with hearvy duty battery cable( about 10ml in diameter). I hope this is satisfactory. My main concern is whether it would charge all three. The fridges seem to draw about 3 amps when they both cut in.
FollowupID: 764169

Follow Up By: Member - Phil G (SA) - Wednesday, Jun 20, 2012 at 18:19

Wednesday, Jun 20, 2012 at 18:19
See how you go with the Redarc - bit borderline for 3 batteries but it depends on how you use them. If it burns the contacts, you'll need to get the 200A model next time!
Cable sounds good.
No major problems with it charging all 3. Your alternator voltage is about 14.3 after startup but the alternator is temperature regulated, meaning the voltage is regulated down (usually around 13.8V) as things heat up under the bonnet. Problem is that the batteries in the back are not hot, so the voltage getting to them can be a bit lower than optimal but only the purists believe this to be a problem. My solution was to put them on a multistage charger occasionally.

Sounds like you've also got the 40 amp engels - measured mine at 2.8A when cycling.
FollowupID: 764184

Follow Up By: Grant W - Wednesday, Jun 20, 2012 at 18:59

Wednesday, Jun 20, 2012 at 18:59
When I am stopped for a while I can connect 2 x 80 potable solar panels as well if stopped for an extended time I move the boat on top which exposes another 2 x 80 watt panels on the roof, the solar regulator inticates battery charge at 100% after a couple of hrs. As I have said I mainly want to keep them going while driving. Thanks for your advice Phil it is appreciated. Cheers
FollowupID: 764185

Reply By: KevKim37 - Friday, Jun 29, 2012 at 13:44

Friday, Jun 29, 2012 at 13:44
Hi Grant,
I have same vehicle with canopy and Rhino boat loader rack, 2 x 80watt panels. I have had an alloy frame fitted around the perimeter of the panels and two lengths of 5mm angle alloy with a milled slot nearly full length and they are bolted to canopy roof. There are extended pivot points on the four corners of the panel frame which I fit lock bolts through on one side for travel and use s/steel toggle end pivot pins (Used in Marine applications) for sliding to either side of vehicle depending on where I pull up. I use a couple of tent poles to support outer ends of framework when slid out.

This allows me to slide out panels either side for solar power while boat is on top. I fitted this setup in 2004 on new vehicle and the alloy slides and framework are holding up great. Trip up Cape York and plenty of bush camp trips west and north of Cairns including being on the road with 22ft van since Oct 2011. The vehicle has only clocked 88000kms and the panel setup has been there the whole time.

Just thought you might be interested in this setup.

Cheers Kev.
AnswerID: 489668

Follow Up By: Grant W - Friday, Jun 29, 2012 at 16:48

Friday, Jun 29, 2012 at 16:48
Sounds like a good setup and might be worth looking into. At the moment I have 2 portable panels that I connect up when we are stopped. I can also slide the boat back a bit to expose one panel on the roof. We will head off for the Burketown area in Juyl August and we will wee how the setup works. There is always the good old generator to top up if needed. The Bushtracker has 3 panels on the roof so with its fridge and the 2 in the ute J should have plenty for a prolonged Bush camp. Thanks Kev

Cheers Grant
FollowupID: 764811

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