question

hoverjocki avatar image
hoverjocki asked

Separate mppt controllers, different power readings.

I have two 370W solar panels each with its own mppt controller.
They are completely separate right up to a bus bar from the mppt output to the batteries.
I am seeing two different power readings like one is doing the work and the other shuts down.
I have them networked with the 702 battery monitor but one seems to do the majority of the charging.
Im not understanding why this is happening.

Battery picture to show setup not actual time of charts


MPPT Controllers
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1 Answer
Justin Cook avatar image
Justin Cook answered ยท

@Hoverjocki, this is normal; the first controller to "wake up" in the day will have a long absorption timer, the second to "wake up" will have a shorter absorption phase and will go to float sooner. This is normal operation, and with your batteries effectively full, is appropriate for your system - this behavior is simply a function of the MPPTs' charging algorithms.

There will be a SmartSolar FW update which brings a "synchronized charging" feature to the SmartSolar operation; once it's set up, the synchronized charging feature will alleviate your concerns, since both controllers will be in the same general state at all times, but it won't significantly impact the charging of your system: in your pictured scenario, you have one controller at idle and one controller putting 3.2A into the batteries (a bare trickle, really, since your batteries are already full); if you had synchronized charging enabled in the chargers, you'd basically just see both putting 1.6A into the batteries - note that the total charge current would stay approximately the same, because full batteries simply won't take much current. But, both controllers will look better because they'll be in the same state.

Once this FW update becomes widely available, you will see an announcement from Victron and the FW update will become available in VictronConnect; until then, however, rest easy in knowing that your controllers are doing exactly what they're supposed to be doing.

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hoverjocki avatar image hoverjocki commented ยท

Thanks a lot

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