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Jim avatar image
Jim asked

Multiplus Starter Battery Port Operation?

The Multiplus manual doesn't have much in the way of details about the starter battery port. I understand it charges at 4 amps and lower voltage. But when does it operate? Is it on all the time or only when AC input is active?


I have the Multiplus 12/3000/120 with a Cerbo GX and a couple of MPPT 100/50.

starter battery
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1 Answer
Alexandra avatar image
Alexandra answered ·

@Jim

It follows the charge cycle of the main house battery. So if bulk then in bulk. If floating then that one will float as well.

As far as i know it does not deplete the main bank for charging the auxiliary battery.

https://community.victronenergy.com/questions/79393/can-i-use-auxiliary-battery-charger-output-4-amp-o.html


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Jim avatar image Jim commented ·
Thanks for that confirmation. The starter battery is for the on-board generator. I need the starter battery to get a charge while the generator is running since the generator doesn't provide a charge to the starter battery.
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Alexandra avatar image Alexandra ♦ Jim commented ·
@Jim

If there are doubts, you could pass it through a different relay and have that relay disconnect on SOC. (So daisy chain it.)

Or simpler would be a switch/disconnect.

Then there will be maintenance of the starter battery but not cycling the house battery.

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derrick thomas avatar image derrick thomas commented ·
The 4amp auxiliary output is always powered regardless of what state the multi is in. The aux output will maintain a slightly lower output voltage than the main battery bank. In theory, if off-grid with no active charging source, the aux output could actually drain the main battery bank if there was a fault in the aux battery such as a shorted cell, which would cause the aux battery to pull the voltage down.
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