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vincentduprez avatar image
vincentduprez asked

How to use multiplus to charge engine battery in a Van ?

I'm working on a van conversion and have installed this inside :

https://www.victronenergy.fr/upload/documents/schematic-vehicle-lithium-rv2-.pdf

The only difference is that I have added victron mppt and solar panels and that I do not have the Orions, and my Multiplus is a Multiplus 800va (the one with a plastic casing 500-800-1200 versions)

The alternator can charge the lithium battery through the BMS 12/200, and the 2 circuits are independent from each other.

Now my lithium battery is fully charged says the BMV, but my starter/engine battery is low voltage.

I've seen in the user manual of the multiplus that it has a second 12v charger. but it only has a Positive (+) connector, I don't understand how I'm suppose to wire this to the starter battery

I also have a ground on the Multiplus, is his one supposed to be connected to the - of the starter battery ?

how does the second charger of the multiplus links to the negative(-) of the starter battery as it is isolated from it by the BMS 12/200.


Subsidiary question : is this second 4A charger only working when there is external 220v or does this also work from 12v energy (say my lithium is at 100% and still full sun outside on the solar panels..?

Multiplus-IIBMS
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3 Answers
wkirby avatar image
wkirby answered ·

The only way I can think of doing this is with an isolated DC-DC converter, more gadgets.

The 4A charger on the MultiPlus only works when mains is present.

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vincentduprez avatar image vincentduprez commented ·

That’s fine with mains.

But I still don’t get how the multiplus connects to the neg of the starter battery. Is it using the grounding attached to the chassis?

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zuzullo avatar image
zuzullo answered ·

Hi Vincent,

Did you find out how to wire it to the starter battery?

It's the connector G. (appendix A)

The wire terminal is supplied with the unit.

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nvs avatar image
nvs answered ·
  • The trickle charger terminal can be used for charging an auxiliary battery such as a starting battery. This is just the positive connection. The battery negatives must be common to each other.
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