Victron Charge Controller Acting Erraticly

[jessicadavis]

I am at a total loss. I have been running my whole system with minimal errors for nearly two years at this point. But all of a sudden I'm experiencing some very erratic behavior, seemingly surrounding my charge controller.


This is my setup:
- (4) 100Ah SOK Batteries, wired in series-parallel for a 24V system


- Victron MPPT 150/45


- Victron MultiPlus 24/3000/70-50 120V


- Victron SmartShunt 500A/50mV


- Victron BatteryProtect and also a Victron Balancer


- Also worth mentioning: Everything is connected via VE Smart networking


This is my problem:


A few weeks ago I started getting an occasional error message on my MPPT (#26 Charger Terminal Overheat). I've checked all connections. Everything is secure, no wires feel warm, everything appears to be totally fine. The error would always go away and things go right back to normal. Figured it was just a fluke.


Then, about a week ago, the MPPT started being very strange. It would be on bulk but bringing in 0w, and then it would switch to Absorption WAY before it was supposed to, it would stay on Absorption long past the Absorption time I have set, then it would switch to Float even though all the devices are reading a low voltage, and then sometimes all my devices are matching voltage, but the MPPT is reading like 3V higher than everything else. It's just all over the place.


I've searched the forums for all these individual problems and tried various solutions. I've checked connections, I've changed settings, I've replaced a fuse that was not making a clean connection. And every time I try something, it appears to be working for a few hours or even a couple days at a time. But then the problems come right back.


Any suggestions??


Below are some pics of my setup in the app - MPPT settings and history - including one shot of the MPPT showing a MUCH higher voltage than everything else.

 

[MisterSandals]

Any suggestions??

It sounds like you've done a thorough job narrowing it down to a faulty SCC. Cheers to buying quality equipment with a 5 year warranty.

 

[chrisski]

I don't think this is your problem with a BMS tripping because of high cell voltage, but I recommend bringing the charge down by a volt and see what happens. You are charging at 3.65 volts per cell which tends to be the highest used for individual cell voltage cutoff on a BMS. I charge my batteries at 3.475 volts per cell.

If SOK lets you monitor cells individually bring that up on the BMS or see if there is any data on the BMS to support this. I don't think you can open an SOK battery up to measure yourself.

I don't know what the indication an SOK BMS has tripped or what to do to reset it.

My only experience with BMS tripping and resetting it is:
-overamps where to reset the BMS I had to unplug the solar; there was no interruption for power.
-Low cell voltage or low battery voltage; this takes either hooking the solar panels up to start charging the battery or jumping it with a powersupply across the battery with 28 volts.

One bad connection on a cell was causing that cell to be much higher than the others and was really close to tripping the BMS for cell voltage.

 

[jessicadavis]

I don't think this is your problem with a BMS tripping because of high cell voltage, but I recommend bringing the charge down by a volt and see what happens.

So on my BMS, I have the Charged Voltage set to 27.6V - are you suggesting I try taking that down to 26.6?

 

[chrisski]

I recommend dropping the absorption to 28.2 on the SCC.

The SCC has a absorption of 29.2 (3.65 per cell) which if the batteries are not perfectly balanced could have the SCC push more than 3.65 to some cells if the others are low.

 

[jessicadavis]

I recommend dropping the absorption to 28.2 on the SCC.

Done!

 

[chrisski]

Done!

I do think you are correct in diagnosing the SCC bad. This is the only other thing I could think of that although very unlikely, may cause some symptoms as you mentioned.

As far as state of charge at 29.2 versus 28.2, very little difference, perhaps 95% versus 100%.

 

[Q-Dog]

When you say you checked all connections, did you remove alll wires from their connections and reattach them?

 

[mikefitz]

Some of the Victron plots show a very low battery volyage, this suggests one or more of the battery BMS has entered protection mode, opening the charge path.
As discussed your charge volts are perhaps too high , and since SOK batteries are often not very well balanced, it's easy to get cell high volts protection.
Victron preset for lithium is 28.40 absorbtion and 27.00 float, there is no need to exceed this, 28.00 volts will still achieve full charge. Rebulk is too high, set 0.4 volts lower than float.

With series parallel it's possible the batteries are not in the same state of charge, worth checking the Individual voltages.

 

[TomC4306]

I do think you are correct in diagnosing the SCC bad. This is the only other thing I could think of that although very unlikely, may cause some symptoms as you mentioned.

As far as state of charge at 29.2 versus 28.2, very little difference, perhaps 95% versus 100%.

Naw. 28.2 with 30 minutes of absorption gets you 100%

 

[TomC4306]

Some of the Victron plots show a very low battery volyage, this suggests one or more of the battery BMS has entered protection mode, opening the charge path.
As discussed your charge volts are perhaps too high , and since SOK batteries are often not very well balanced, it's easy to get cell high volts protection.
Victron preset for lithium is 28.40 absorbtion and 27.00 float, there is no need to exceed this, 28.00 volts will still achieve full charge. Rebulk is too high, set 0.4 volts lower than float.

With series parallel it's possible the batteries are not in the same state of charge, worth checking the Individual voltages.

And I see some very high voltages. Over 32 volts