How to limit bulk charge current from MultiPlus when simultaneously charging with alternator?

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simada asked Jun 14, '23

How to limit bulk charge current from MultiPlus when simultaneously charging with alternator?

I have a 500 Ah battery bank recharged either by the Victron MultiPlus 12/3000/120 inverter/charger (via generator or shore power) or by the boat engine secondary alternator. Max allowable bulk charge rate is normally 100 A from either source. To verify this, I have a BlueSea Systems 1830 SoC meter with inline shunt resistor for current measurement.

Problem is that I measure 194 A going into the batteries during initial bulk charge when both sources are active.

Is there a way to wire the "smart" Victron MultiPlus to sense current at the battery so that it can compensate for the current coming from the "unintelligent" alternator?

battery charging charge current limit

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Answer 1 · 2023-06-14T17:32:28Z

janieronen answered · Jun 14, 2023 at 05:32 PM

Unfortunately you need to change shunt to Victron shunt or add it as second shunt. Without shunt Multiplus cannot know how much other appliances are feeding to battery.

Some workarounds are but these are not optimal like if you can get charge active signal from alternator/engine. That can be feed to the Multiplus example from motor running signal can be sent trough relay to Multiplus. Then you need to add assistant program to Multiplus which will stop charging when input is active.

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Answer 2 · 2023-06-14T19:47:11Z

simada answered · Jun 14, 2023 at 07:47 PM

Thank you for the suggestions. I think I understand the second (less optimal) option that uses a signal from the engine to stop the MultiPlus via relay.

I agree that the first option is best and would like to implement it. But I can't figure out what Victron shunt works with the MultiPlus. Can you please tell me the model number or description of the Victron shunt? I could only find AC (not DC) current sensors on the Victron web site.

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