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sroxbee1 avatar image
sroxbee1 asked

VW T5 Wiring with Solar and Split charging systems

Good afternoon all,


**Updated wiring Diagram in response to advice.


I am planning my VW T5 Day/Fishing van wiring and would like to ask opinions to make sure that I haven't missed anything.

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I have a 120W panel with Victron 75/10 MPPT controller. This is going to be connected to a 95Ah leisure battery in parallel to a split charge VSR circuit.


I have one USB socket that will be permanently fed (for rear passengers), and then the leisure circuit will be isolated via a switch, with other accessories switched at the rear of the van.

The largest draw will be from my 3-way fridge that will be supplied 12V whilst in transit (it will be gas fed outside the van when camped), so I foresee periods of 1 hour or so where leisure battery alone will provide power (when on Eurotunnel for example) for which my Dometic RM8501 draws 10.8A.


Thank you in advance for any comments.



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2 Answers
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kevgermany answered ·

If you put a load on the system that's higher than the solar is generating, the extra is provided by the battery.

So you need to estimate total load on the system over the day, and balance that against what you expect the panel to generate over the day.

Panel gets dedicated wiring to the controller, via an isolator switch. Battery gets dedicated wiring to the MPPT. As drawn the only way to isolate the house battery is by pulling the fuse, you might want to consider an isolator switch. And negative should be grounded to the vehicle. You could use the chassis/body wiring for the negative rail but probably better not to.

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sroxbee1 avatar image sroxbee1 commented ·
Thanks @kevgermany,


The MPPT panel load channel is protected was my main concern with the initial Q about could the load be too much. The main use for the USBs/CL points will be charging fishing/camping gear, but I will have a 3 way fridge plugged into a CL for when travelling to venue. This should be OK with engine running, just wondering if maybe an hour on the tunnel will drop the Leisure to below the 11.1V cut-off through the MPPT.


What is your concern for having an isolation switch on the leisure battery? Ease of maintenance?

Charging and separation is taken care of by the split relay (on at 13.3V off at 12.8V) so I don't have an issue there.

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kevgermany answered ·

Cut off - partly ease of maintainance, also when you disconnect a terminal, it sparks a lot. Can also use it to prevent unwanted drain down from other kit (like USB ports) when not it use.

Three way fridges eat a lot of power. Assuming 10A over an hour, your battery should cope.

Update, your solar panel won't cope, except on really fine days, and then maybe...

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sroxbee1 avatar image sroxbee1 commented ·
Fridge is 3 way, so when on site will be gas powered.


All of the outputs will be individually switched from the control panel, but I take your maintenance point and will put in a master switch by the Vehicle battery side fuse.

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