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Solar charging and battery layout?


Beer moth

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Hello All,

 

First time posting here and apologies if this has been covered or in the wrong place.

 

I have a self built camper and use quite a lot of power, generally off site. Question is I am after theories for the most efficient layout of the system, the components I have I will list below:

 

3x 150w BP Solar panels, roof mounted approx 21-28v

2 x 30a charge controllers

1 x 2000w invrter 12v

2 x 200ah agm batteries

 

Vans battery 12v with a Tmax split charge to the leisure batteries for charging when running.

 

At the moment I have two panels in parallel charging the leisure batteries 12v with inverter running off them.

 

The eberspacher heaters water and air run off the van battery, I can change them to the leisure batteries but it would be grief as one is factory fitted.

 

My thought is to link all panels to a charge controller to feed the vans main battery, so it is always charged, when full the Tmax would kick in to charge the leisure batteries that way all batteries would be fully charged as long as there is enough sun?

 

Am I missing something?

 

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I'm puzzled as to why the eberspacher is running off the vehicle battery, I'd swap this over to leisure battery, if there are concerns as to warranty I'd contact dealer and tell them the present set up is not fit for purpose as using the eberspacher could imobalise vehicle.
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Normal arrangement is to charge the leisure battery to 80% then feed a trickle charge to the engine battery. Solar regulators that have outputs for 2 batteries normally allow you to set the switch over point for when they start charging the engine battery usually 50, 80 or 90%.

 

Elektroblock (used in a large proportion of continental vans) charge the leisure batteries at a max of 18 amp up to 80% then they allow a trickle charge to the engine battery with a max of 6 amp.

 

As Colin says get the heater swapped to the leisure batteries, you can survive a flat leisure battery but a flat starter battery and you are stuffed.

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colin - 2014-07-13 8:30 PM

 

I'm puzzled as to why the eberspacher is running off the vehicle battery, I'd swap this over to leisure battery, if there are concerns as to warranty I'd contact dealer and tell them the present set up is not fit for purpose as using the eberspacher could imobalise vehicle.

 

Beer moth's motorhome is a 'self build', so (presumably) on a panel-van base. It's quite common for Eberspacher heaters to be factory-fitted to certain makes of light commercial vehicle (eg. Mercedes Sprinter, VW Crafter, Renault Master) in which case the heater will be powered by the vehicle's engine-battery as this will be the only battery available.

 

I agree that it would be preferable to have all 12V 'habitation' components (particularly the heaters) powered from the leisure-batteries, with a 'trickle charge' link from those batteries to the engine-battery to maintain the latter's charge-state.

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Firstly thank you for your replies.

 

I didn't want to ramble on too much to start with but correct it is a sprinter with factory aux eberspacher water heater.

I have built the over ride relay bank so it can operate as per factory or flick the switch when parked up and it will heat water circuit, which I can divert to a heat exchanger and have endless hot water. This works really well even if I pay for it in diesel? I think I will be powering this from the leisure side once I make sure I don't get any sort of feedback through relays to vehicle ignition or anything (that's the hassle part)

There is a air eberspacher that I will also now look at powering from leisure batteries originally fitted as it was a minibus.

I think I need to investigate the better solar charge relays to charge both systems as suggested as mine I suspect are cheap Chinese..........

Anyone any ideas about wether there is an advantage to running the panels in series as long as I don't overshoot charge controller voltages as could this alow me some charge on cloudy days even though at lower current?

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