question

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MPPT 150/45TR tripping inverter with overvoltage

Here is my configuration:

four 175W HQST panels in series (Open-Circuit Voltage (Voc): 24.3V, Optimum Operating Current (Imp), 8.62A), VE MPPT 150/45TR SCC, four 12V LiFePO4 (105Ah) in parallel, Giandel 12V 2200W inverter.

I have this problem that the inverter is constantly tripping on over voltage (16V or higher). The VE 150/45 surges over 16V when cloud cover opens quickly, and the draw on the inverter drops as well. I have set up a "Battery Preset" customized for the batteries and it works fantastic. The inverter manual suggests to not use the inverter if overvoltage shut downs occur. That defeats the purpose of having solar. Any ideas?

Is there any way to limit the power spikes/surges on the controller?

MPPT - Solar Charge Controller
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3 Answers
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repro answered ·

The batteries are 4 Lion Energy UT-1300’s with built in BMS.

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repro answered ·

356eb5a7-8575-4e40-bb97-455279050e9b.pngScreenshots uploaded. The batteries are Lion Energy UT-1300’s with very good built in BMS.daf6db02-ae70-47c4-b08e-5bdffaf4b9bd.png8814ca5f-c1a5-4c04-b4f1-0998b7cd92b2.png


5 comments
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Does that over voltage issue happens only when the batteries are full or close to full?


I can't see anything in the settings which would explain those 16V.

But the absorption voltage is set at maximum allowed for LiFePO4.

Also I found this here:

Victron inverters charger and charge controllers should be set to 13.9 volts for a 12 volt inverter and 27.8 for 24 volt inverters.

Maybe lower it to 13.9V-14V and see how it goes.


Not a cause of you issue, but your Float voltage is somewhat high. Set it to 13.4V.

You could also enable Tail current.

Yes, it does happen when the batteries are close to full (Absorption phase). I am using the charging voltages that Lion Energy gave me. Actually, they suggest 14.6V for absorption, I never go above 14.4V.

I will lower the absorption setting to 14V and the float to 13.7V and enable tail current. I feel that my batteries will live longer with those settings.

Hey, thanks for the help! I am changing the settings now and will let you know how is goes.

float to 13.7V

It's too high. Set Float voltage to 13.4V, like I wrote.


I could not find if the BMS from your batteries can disconnect the battery to protect it from overvoltage. If it can, this might explain the behavior you see.


Set the Tail current to 3-5% from your battery bank capacity (105Ahx4=420Ah). So around 15A. Observe how it behaves and adjust.

The purpose of this tail current setting is to end the absorption stage when the current taken by the battery drops under this level (which normally indicates that the battery is full).

The problem with using this with a solar charger is that the current can drop because a cloud is shading the panels, so it might end the Absorption stage too soon. That's why you want to experiment with the Tail current value, until you find a good compromise.

Also, you can adjust the Absorption duration, if needed.

I set absorption and float both to 13.9V and the problem has disappeared. Thanks for your help!

I have to say again: set the Float voltage to 13.4V.

If the battery is still not fully charged when Absorption stage ends, just increase the Absorption duration. Do not increase the Float voltage.

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seb71 answered ·
I have set up a "Battery Preset" customized for the batteries and it works fantastic.

Sounds like you might have Equalization enabled. Otherwise the SmartSolar charger should not get to such high voltage. Or maybe it's defective.


Can you post a screenshot with those battery settings?


Also, those LiFePO4 batteries have some BMS?

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