Charging Auxiliary battery

Submitted: Saturday, Dec 19, 2015 at 17:12
ThreadID: 131164 Views:2310 Replies:7 FollowUps:7
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I realise that this question has been asked before but I can't find the answer on a search.

I have a 200 series with an 80 AH deep cycle auxiliary battery connected via an ARB auxiliary battery kit that came with the vehicle when I bought it second hand. But this battery is not quite man enough to run our 95 litre Ecakool for more than a day or two in hot weather.

I have ordered a 200 watt solar panel to go permanently onto the roof rack and an Victron MPPT controller to keep the juice up to the auxiliary battery when parked. I plan to connect the regulator direct from the panel to the battery.

When running the engine, will the car's alternator and the solar regulator get in each other's way?
Or do I need to put a relay in to isolate the panel when the engine is running?

Many thanks in advance
Keith
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Reply By: Loddo48 - Saturday, Dec 19, 2015 at 18:16

Saturday, Dec 19, 2015 at 18:16
Hi Keith
they will happily work together ,the one with the higher voltage will have precedence over the other once the battery voltage starts to rise .
I have a 105ah AGM battery under the bonnet and 160w panel on the roof and have just returned from the Kimberley after 9 mths and this is how my battery is charged. ran the fridge as a freezer in the back of the 200 with no problems
John
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Reply By: Member - DOZER - Saturday, Dec 19, 2015 at 18:17

Saturday, Dec 19, 2015 at 18:17
i wont try to answer your question, but i can say there is a charge fuse with a diode in it, that allows the alternator to charge at a higher voltage, recharging your batteries quicker and more completely. Adding this fuse would charge your auxiliary battery to a higher voltage giving you more fridge run time. From memory, the 200 alt charges a 13.6 volts and adding the diode fuse increases this to 14.2, which is what the older cruisers used o charge at.
b4 you bag me out, walk a mile in my shoes, then your a mile away and have my shoes :)

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Follow Up By: Member - DOZER - Saturday, Dec 19, 2015 at 18:21

Follow Up By: Sigmund - Sunday, Dec 20, 2015 at 05:39

Sunday, Dec 20, 2015 at 05:39
That's higher than recommended for an AGM once charged.
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Follow Up By: Member - KeithB - Wednesday, Dec 23, 2015 at 12:10

Wednesday, Dec 23, 2015 at 12:10
Thanks Dozer.
I just ordered one.
Keith
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Reply By: Gronk - Saturday, Dec 19, 2015 at 21:49

Saturday, Dec 19, 2015 at 21:49
In reply to your question, no they will not get in each others way. But normally you won't have a solar panel and the engine running at the same time anyway.

Running a fridge for 2 days is a big ask from a 80a/h battery and I'd guess it will be fairly flat after 1 full day. So, the solar panel is a good idea. I have a 140W panel that I attach to my roof rack and have it "hinged" so it can roughly face the sun.
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Reply By: Frank P (NSW) - Sunday, Dec 20, 2015 at 10:07

Sunday, Dec 20, 2015 at 10:07
Hi Kieth,

My recommendation is to leave your alternator charging system as standard and install a dc-dc charger that has solar input as well.

Redarc make one (link). Expensive but very good. Also the Ctek D250S (link) but there have been reports within our club of less than optimal solar performance. A bit of research required. Both can be sourced at cheaper than RRP prices on eBay, but check out warranties before going that route.

I think your 80Ah battery might be a bit small. If you upgrade it, try to find one where the battery manufacturer's maximum recommended charging current matches or exceeds the amperage output of your chosen dc-dc charger.

AFAIK the Redarc can live under the bonnet if there's room, but I'm not sure about the Ctek. Best do some research.

Did I help you with solar panels some years ago? Name rings a bell :-)

Cheers
FrankP

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Follow Up By: Frank P (NSW) - Sunday, Dec 20, 2015 at 12:36

Sunday, Dec 20, 2015 at 12:36
And to directly answer your question, Keith, in the setup you have proposed I would use an ignition controlled relay. It has been the experience in our club that when multiple charging sources are available, it is better to have only one in operation at a time - unless you have a device that integrates the sources, like the two in my reply above.

BUT - check with Victron to see if it's ok to leave the solar connected when the relay disconnects and re-connects the battery. Some regulators don't like that and need the solar to be disconnected while making or breaking connections between regulator and battery.

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FrankP

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Reply By: noggins - Sunday, Dec 20, 2015 at 10:25

Sunday, Dec 20, 2015 at 10:25
I run 2 x 100W ex Telstra batteries in the back of the Ranger sitting over the wheel arch.
I have a 160W solar on the canopy with a cheapy regulator and also charge from the alternator via an ign controlled relay.
I have 2 batteries and 2 fridges , 1 as a fridge and 1 as a freezer. No worries in keeping everything cool / frozen for any length of time as the solar can cope with charging for ( did it once ) 6 days before I moved the Ute
I'm a firm believer in the K.I.S. principle and don't believe that a very costly system will do a better job when something simple works 100%.


ZZ
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Follow Up By: Gronk - Sunday, Dec 20, 2015 at 12:40

Sunday, Dec 20, 2015 at 12:40
Exactly.....what he has is doing the job, if it needs a tweak, then a booster diode is heaps cheaper than a dc/dc device.I have one in my 200 and it works great.
But as long as the sun shines, the setup he has is good.
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Reply By: Member - Phil G (SA) - Tuesday, Dec 22, 2015 at 21:56

Tuesday, Dec 22, 2015 at 21:56
I assume your 80Ah aux battery is under the bonnet.
That being the case, you need to consider temperature compensation.
If you have 200W of solar (i.e. heaps) and a regulator mounted inside the air conditioned cab, and the battery sitting in 70 degree heat under the bonnet, then you will boil the battery.
AnswerID: 594074

Follow Up By: Member - KeithB - Wednesday, Dec 23, 2015 at 09:29

Wednesday, Dec 23, 2015 at 09:29
Good point Phil. In fact the Instructions for the Victron MPPT controller says the same thing. The problem is that, with all of the accessories already under the bonnet, there is not a single space for me to mount the controller.
It has an ARB third battery kit which charges the auxiliary battery when the engine is running. It's only when stationary that the battery can't keep up with the fridge.
So I am wondering what will happen if I mount the controller inside the car and fit a relay so that the solar panel is out of the circuit when the engine is running.
Might that work?
Many thanks
Keith
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Reply By: Batt's - Saturday, Dec 26, 2015 at 22:34

Saturday, Dec 26, 2015 at 22:34
I recently bought a 105 AH agm for my 47 ltr Evakool good for around 2 days. I purchased another 105 AH yesterday $239 delivered to Mackay from Aussie Batteries they have a sale on till the 31/12/15 great prices http://www.aussiebatteries.com.au/.
I will fit a solar panel later on probably get it from Bit Deals they have been getting good reviews on 4WD sites.
AnswerID: 594181

Follow Up By: Batt's - Saturday, Dec 26, 2015 at 22:42

Saturday, Dec 26, 2015 at 22:42
My Evakool is 11 yrs old, a bit power hungry it draws around 3.2 amps when used as a fridge/freezer that's why I went for 2 batteries. I have previously only run it off my starter battery for up to 2 days max without trouble it's a 105 AH Supercharge Allrounder the first one lasted 5 yrs 3 months I was happy with that so I replaced it with the same one again.
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