Victron MPPT 75/15 seems to have a voltage measurement glitch

[rin67630]

Hi,

I have to report a possible software glitch with a Victron MPPT 75/15 connected between 2x 425W panels (MP@38V) in // and a 12V/100 Ah LiFePo battery.

The charger worked perfectly with a 12V Gel battery, once I replaced it with a LiFePo (with according settings) it loads until 13,4V and then the (at Victron VE port and at the Victron BLE app) shown battery voltage jumps to 14,2V (effectively still remaining 13,4V at the battery terminals).
In consequence the SCC stops charging.
That problem has been reported by others too.

Victron does not seem to want to correct the glitch, they refunded the device with no further action.
Regards
Laszlo.

 

[Brucey]

Hi,

I have to report a possible software glitch with a Victron MPPT 75/15 connected between 2x 425W panels (MP@38V) in // and a 12V/100 Ah LiFePo battery.

The charger worked perfectly with a 12V Gel battery, once I replaced it with a LiFePo (with according settings) it loads until 13,4V and then the (at Victron VE port and at the Victron BLE app) shown battery voltage jumps to 14,2V (effectively still remaining 13,4V at the battery terminals).
In consequence the SCC stops charging.
That problem has been reported by others too.

Victron does not seem to want to correct the glitch, they refunded the device with no further action.
Regards
Laszlo.

View attachment 214386

This looks like the lfp battery bms is disconnecting (i.e. cells out of balance and one has hit an overvoltage limit). I would set the bulk at 13.2V, over time increase that slowly to 13.6V and with cycles the LFP battery should balance out. At 13.6V you are already basically fully charged:

A chart from a member here:

 

[rin67630]

This looks like the lfp battery bms is disconnecting (i.e. cells out of balance and one has hit an overvoltage limit). I would set the bulk at 13.2V, over time increase that slowly to 13.6V and with cycles the LFP battery should balance out. At 13.6V you are already basically fully charged:

A chart from a member here:

I dont believe that: I measure a stable 13,4V voltage at the Battery terminals of the Victron SCC, whereas it shows 14,2V at the VE serial port and at the Victron BLE app.
If the BMS were disconnecting, I'd have 14,2 at the Battery terminals.

 

[Brucey]

I dont believe that: I measure a stable 13,4V voltage at the Battery terminals of the Victron SCC, whereas it shows 14,2V at the VE serial port and at the Victron BLE app.
If the BMS were disconnecting, I'd have 14,2 at the Battery terminals.

So they refunded your money. Did you get a replacement that also has the same problem?

Was it running the latest firmware? I know there was some issues a while back where their SCCs would hang or something like that in an edge case.

Also how many amps are you running into that 75/15? Running the two panels in parallel? Should be fine if they aren't wired in reverse.

 

[rin67630]

So they refunded your money. Did you get a replacement that also has the same problem?
Was it running the latest firmware? I know there was some issues a while back where their SCCs would hang or something like that in an edge case.
Also how many amps are you running into that 75/15? Running the two panels in parallel? Should be fine if they aren't wired in reverse.

I have just sent the 75/15 back, waiting for a refund.
It ran the latest firmware.
Since this problem has been mentioned by some others too, I believe in a general problem and did not want to get it again.
Meanwhile I have ordered a 100/20, hoping that it will not have the same glitch.

I was not running it at full power, limited it to 4A which is enough to recharge the battery, which just powers a router 24/24 at 10W.
I run heavily over-panneled to get some juice in winter too.

I hope the 100/20 will begin to work with low irradiance too.