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?
asked
75/15 jumping between amps on absorption charging
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.
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.
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.
Your battery voltage is jumping all over the place.
Looking like bad battery or wiring.
But the battery voltage depends on the charger, when it pushes amps the voltage goes up too. Is there something I'm missing here?
And why would battery voltage not jump around when a load is present? The battery voltage does not jump around except when the mppt is charging without load on the battery during maximum sunshine.
I am seeing that the battery voltage goes low, and that the mppt responds by allowing current to flow to the battery.
The reaction from the (unknown load) seems to drop the battery voltage significantly.
The batteries reaction to the mppt's charging current seems to have a disproportional voltage rise response.
Ok, i understand, that's a good observation. I will check my battery wiring again thoroughly and report back.
Also check the fuse(s) in the mppt / between the mppt and battery.
I once had the fuse between the mppt and battery blow, and the mppt still tried to power the loads. It was confusing, and strangely interesting.
