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sebastiangabler avatar image
sebastiangabler asked

Caravan external second battery

Hello

In my caravan there is a MP12/1800 with a 12V 100Ah battery. On the roof a quite small PV with an MPPT to load the battery, controlled by a Cerbo GX and a Smart Shunt to measure the voltage/current.

Now I want to extend this setup with a big problem. Because of weight and space problems I’m not able to build a second battery in the caravan and also there is no space for mir modules on the roof.

Now my idea: build a box with battery, MPPT, shunt and temperature control where I can connect additional modules. With a plug near the first battery I want to connect DC and data communication in my caravan.

Now the question: is this possible. Can the Cerbo handle this installation, do I need a second Cerbo in the box or is it still not possible.

Thanks for your time to think about!

Regards

Sebastian

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2 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

The Victron ecosystem currently does not support two battery banks in the same system. They would need to be completely independent which minimizes integration.

You didn't mention battery chemistry. Connecting lead acid batteries together might be OK but lithiums at different state of charge suddenly connected together might result in a larger current flow until they equalize.

One way around this is to connect your external power source via a DC to DC charger. This would manage current to avoid huge spikes and keep batteries safe and would also allow different chemistries and battery voltages. The down side is the energy loss due to converter efficiency.

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sebastiangabler answered ·

Thanks for the answer. Thats a good idea with the DC-DC converter. Which one would you prefer?
Do you think that the Orion XS can handle this? Also in combination with a MPPT and the Cerbo?

There will be two lithiums in the system, so your consider in the right way.

BR
Sebastian

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Kevin Windrem avatar image Kevin Windrem commented ·

Victron just released the Orion XS. It's 12 volt to 12 volt 50 amp max but in and out currents are adjustable. Very high effeciency: 98.5%. Integrates with GX device via VE.Direct.

These can be paralleled if you need more than 50 amps.

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