Inverter powers off (input overvoltage) BMS guilty or....?

[Maniac54]

More than a year ago I replaced my gel batteries with lifepo4 24v setup. Inverter is a 4000w Westech. First 5 months were fine but then after upgrading batteries and smart BMSs inverter started power offs. At some point I had many failures and had the chance to identify input over voltage reason, check here

. Then I replaced BMS with another similar (dally) and was better, took 20 days to next power off.
I have done some equipment combinations but haven't identified the source of problem.
Any ideas for possible reason?

 

[newbostonconst]

Is "equalize" turned on in your charger? It shouldn't be.

Charge cycle is normally: Bulk, Absorb, Float, and then Equalize is an option for Lead Acid Batteries.

 

[Maniac54]

Is "equalize" turned on in your charger? It shouldn't be.

Charge cycle is normally: Bulk, Absorb, Float, and then Equalize is an option for Lead Acid Batteries.

I think it is, duration value is 120, should I set it to 0?

 

[newbostonconst]

I think it is, duration value is 120, should I set it to 0?

yes, try that...

 

[12VoltInstalls]

yes, try that...

Isn’t his overvoltage setpoints incorrect too?

 

[newbostonconst]

Isn’t his overvoltage setpoints incorrect too?

Yes, that could be raised to 28.0 volts also.

 

[Maniac54]

Yes, that could be raised to 28.0 volts also.

That was part off experimenting with different values. Regarding equalization, power off happened at least once early in the morning when voltage is usually around 26.2. Does this make sense?

 

[Maniac54]

An update on this problem. My last modification was using a dump YIT BMS. After 2 months of operation I had 0 inverter failures. Seems Daly for some reason raises voltage over the limit. I am not qualified to say that daly is a crap but at this case it is useless. Maybe there is an equipment incompatibility issue. Unfortunately I have not a second inverter to test.

 

[mikefitz]

What are the cell volts when the problem occurs. My guess is the bms seeing cell overvolts and opening the charge path, could be due to a bad cell, cell imbalance or interconnection issue.

Mije

 

[Alice2021]

There is a BMS in Lifepo4 battery, for your 24V battery, once its voltage is more than 28V, the battery will be in protection and stop dc output, then the inverter will be in high voltage protection, now please disconnect your battery from charger or solar panel,the inverter will work normally.Please try.

 

[Ellcon123]

If it is a FET based BMS then only input/charge will be stopped at high voltage. Inverter should still be loading battery.

 

[Maniac54]

What are the cell volts when the problem occurs. My guess is the bms seeing cell overvolts and opening the charge path, could be due to a bad cell, cell imbalance or interconnection issue.

Mije

I have done a lot of testing so I have tried with three different battery banks and always had the same problem. Having a bad cell in all three banks is not probable. After the failure bank voltage is correct and I have never seen abnormal cell voltage.

 

[Maniac54]

There is a BMS in Lifepo4 battery, for your 24V battery, once its voltage is more than 28V, the battery will be in protection and stop dc output, then the inverter will be in high voltage protection, now please disconnect your battery from charger or solar panel,the inverter will work normally.Please try.

bms should stop charging batttery when at set point, not disconnecting dc. In my case there is no disconnection, voltage increase only see video.

 

[Maniac54]

If it is a FET based BMS then only input/charge will be stopped at high voltage.

I agree

Inverter should still be loading battery.

How? battery is input to inverter

 

[Ellcon123]

Yes, battery is input to inverter. BMS has stopped power going into the battery from solar or generator but discharge is still open. Inverter still sees the battery.

 

[Alice2021]

Yes, battery is input to inverter. BMS has stopped power going into the battery from solar or generator but discharge is still open. Inverter still sees the battery.

Yes, BMS has stopped power going into the battery from solar or generator, so the solar or generator goes to inverter directly,then over voltage protection happen. So please disconnect solar or generator when battery full charger, the problem will solve