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haufenprinzip avatar image
haufenprinzip asked

Reset MPPT 75/15 to 12 V without USB/Bluetooth

Hi,

it seems that my MPPT 75/15 has changed from 12 V to 24 V and is overcharging my 12 V Batterie. Is there a way to manually put it back to 12 V? I am on a road trip right now and have no way to get my hands on a bluetooth/USB dongle.

I tried disconnecting the solar and the battery and reconnecting (first the battery to make the controller recognize the voltage, then the solar) but that didn't help. Does the controller need some time without current or do I need to wait some time before reconnecting the solar?

Any help would be much appreciated!

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haufenprinzip avatar image haufenprinzip commented ·

I was able to charge the battery with a different controller, a very basic one. I noticed that the Voltage drops relatively fast (even without load) to 13.03 V. That was also the case when charging with the MP 75/15. Is it possible that the battery is flawed and that this causes the overcharging?

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Paul B avatar image
Paul B answered ·

Disconnect it for 5 min

reconnect the battery first then the solar.


the system shoiuld autodetect 12 volt and setup accordenly.

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haufenprinzip avatar image haufenprinzip commented ·

Looks like that worked, thanks Paul! Any idea why the controller changes to 24 Volts? My friend has the exact same setup and had the same issue.

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haufenprinzip avatar image haufenprinzip commented ·

Spoke to soon... So at first everything looked fine. It was charging slowly to 13.8 V and then even slower. A few minutes later i checked again and it was back over 15 V.

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JohnC avatar image JohnC ♦ haufenprinzip commented ·

Some discussion on this, just yesterday: https://community.victronenergy.com/questions/12880/mppt-7515-stuck-in-bulk-charge-mode.html

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haufenprinzip avatar image haufenprinzip JohnC ♦ commented ·

Thanks John. I ordered mine in April 2017 so it should still have the automatic detection feature (not 1-time). Does anyone know, what causes the wrong detection? Had no issues for almost 2 years now.

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