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bobdylan avatar image
bobdylan asked

75/15 jumping between amps on absorption charging

Hello, my charger has worked well over the years but I just discovered this strange behavior in full sunshine. Does anyone know what can cause this?

MPPT Controllerssmart solar charging behaviour
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3 Answers
Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

@bobdylan

Unless you have a BMS in your system, which switches the battery on and off, this could be a wiring issue on either the PV or battery side of the MPPT. I guess the connection between the MPPT and the battery, since the battery voltage displayed varies considerably.

I suggest check wiring and connections.

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bobdylan avatar image
bobdylan answered ·

The behaviour appears to have resolved itself overnight. Very strange. I wonder if it was a SW error? I checked the connections and they are firm between battery and mppt. Between mppt and PV there are several joints so if this problem returns I'm going to go through the MC4 joins because I had lots of problems with MC4 in the past.


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bobdylan avatar image
bobdylan answered ·

Hello,

I have been able to document the issue properly. My narration wasn't picked up by the screen recorder. For the first half of the video, you see my Victron charger with minimal load, jumping around extremely.

Towards the middle of the video, I add a big load, and the charger stops jumping around and stays firm at high amps.

I then turn the load off, and the charger again begins to jump.

This should not be a wiring issue since the charger is able to charge without extreme fluctuations when a load is present.

Could my Victron MPPT 75/15 have a hardware or software issue? How long do these charges typically last? Such massive swings in voltage is not ideal for my DC loads. My fan for example does not like it, you can audibly hear the voltage fluctuations it in it's operation.



5 comments
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klim8skeptic avatar image klim8skeptic ♦ commented ·
Your battery voltage is jumping all over the place.

Looking like bad battery or wiring.

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