question

cas avatar image
cas asked

Can I charge from a generator AND my MPPT at the same time?

I have an off grid system. 150/100 SmartSolar MPPT, multiplus 2 3000 24 volt, smartshunt and a Cerbo. 4 batteries, 2 banks of 24v each 460Ah total. When I start my generator during the day my MPPT stops charging. Is this normal or can I have the MPPT keep charging and supplement with the multiplus charger?

battery chargingsmart solar charging behaviour
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4 Answers
conkev23 avatar image
conkev23 answered ·

Hmmm...I would think so, are you using anything to limit the current going into the battery?
Smart shunt, Smart BMS,...etc

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cas avatar image cas commented ·
Yes, sorry. Updated post with that info. Currently I only have 1440 watts of panels, batteries are capable of the full 100 amps from the MPPT but I cannot supply that much anyway. I don’t have any limiting that I am aware of. MPPT is set to 100 and MP is at 70 amps.
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Michelle Konzack avatar image
Michelle Konzack answered ·

It seems, the charging settings from your MultiPlus-II and the MPPT are different, speak, the values of the MultiPlus-II are to high or the values of the MPPT to low.


Both should have the same.

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cas avatar image cas commented ·
I have read and followed everything I can find. I have to the best of my knowledge set both units to the same voltages and times for charging but it still shuts the MPPT down and I can’t figure out why. I am obviously missing something, but what? Also I wanted to verify that this IS possible.
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conkev23 avatar image conkev23 cas commented ·

Are you running any assistants?

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cas avatar image cas conkev23 commented ·
No. I don’t know how to use those or if I need them.
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conkev23 avatar image conkev23 cas commented ·
ok, I am debugging my system at the moment so I cannot test it out on mine.

Someone that has a similar setup may be able to chime in give more insight.

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Kevin Windrem avatar image
Kevin Windrem answered ·

Your GX device (Cerbo) has a function called DVCC where you can set a maximum charging current for your battery. The GX device then controls the charging current of one or more of the devices to insure that maximum is not exceeded. Each device can set its own maximum charging current and that will limit the device's output if needed for other reasons. Otherwise, set these to their max default value.

It is possible that DVCC is currently active and set to 70 amps in which case the MPPT may be throttled to zero.

Without DVCC, you need to set the charging limit so the sum of all devices does exceed the battery maximum. For your system for example, you could set the Multi and MPPT to both 50 amps. But then if there's no solar, the Multi would only provide 50 amps. It's better to use DVCC.

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JohnC avatar image
JohnC answered ·

@cas

Make sure your charge settings are identical on both units, including Temp Comp if you're using that. Except for one - set Absorb V of the Multi slightly lower than the mppt's, and the mppt will then take priority. 0.1V difference is usually plenty, but you may get away with less on a stable system. Your genset should be off in a Float situation, so unnecessary there.

Nice too if both units see an identical Vbat. Use DVCC's SVS to ensure that's in place.

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