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Paul Stafford avatar image
Paul Stafford asked

What will Multiplus do in this situation

System is a Cerbo GX, Multiplus, Lynx, and MPPT 100|50, installed in travel trailer. 600W of solar panels. I'd like to run the fridge on AC while driving. If full sun, the panels will be enough. If towing in early morning, then the only 12V sources are the 7 pin connector from the tow vehicle and/or and the trailer batteries feeding the Multiplus. The fridge draws 300W, roughly 23 A. Where will the power come from? Is it possible to damage the alternator with this draw (2017 Dodge 3500 Cummins).

Multiplus-IIbattery charging
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Juha Tuomala avatar image Juha Tuomala commented ·
Subject: Will Multiplus charging load damage engine alternator?


People use search and can't figure out your thread content.

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4 Answers
Rob Duthie avatar image
Rob Duthie answered ·

Hi


You need to fit a DC to DC Charger to protect your alternator as a dead or low battery will pull a lot current from the alternator, your cables from the alternator should be upgraded as well, Use the Victron Orion DC to DC charger. this is what i use in truck to trailer charging systems and Ute to caravans systems.

Regards

Rob D

NZ

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Kevin Windrem avatar image
Kevin Windrem answered ·

I have a 3-way fridge (AC, DC, propane) and run it on DC while driving so I can leave the propane off. I have two 180 watt solar panels on the roof and 2,400 WH of battery. The fridge draws a little under 200 watts from either AC or DC and while the solar panels don't completely keep up, I usually don't run much below 80% SOC after driving 4 or 5 hours. I do not have a 12 volt connection to my tow vehicle but may someday add a DC-DC charger.

Running on AC is a little less efficient but is still doable especially with that amount of solar.

As Rob says, isolate the two electrical systems for component protection and size your wiring from the tow vehicle's battery to the 7-pin to carry the needed current without significant voltage drop.

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Paul Stafford avatar image
Paul Stafford answered ·

thanks guys.

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dfk avatar image
dfk answered ·

Our van is very similar to Kevin's and here are the measurements from running the fridge off the Multiplus AC for a particularly windy afternoon and evening while we were away from the van and I was concerned that the wind might blow out the propane heater:screenshot-from-2022-09-01-15-32-07.png


And here the SoC. Our battery bank is 160Ah @ 12V, again similar to Kevin's.

screenshot-from-2022-09-01-15-32-26.png


Enjoy,


Daniel


screenshot-from-2022-09-01-15-32-07.png (46.7 KiB)
screenshot-from-2022-09-01-15-32-26.png (11.4 KiB)
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