Hi Everyone

So we've been experiencing some issues with our TheSunPays LiFePO4 batteries.
We have 3 x 4.8kw batteries and have looked after them quite well, using only the manufacturers settings and never going outside of this.

For the last couple of months though, we've had a problem. If the batteries dip lower than 25%, the voltage drops off massively and then we can never get it back up to 100% without TSP connecting to the batteries and resetting them.

Todays loadshedding caused an issue where we were on 50% at 10am and had 4 hours of loadshedding with little sun in Cape Town. The batteries hit 20% and within a matter of seconds dropped to 13% at 44v (cut off voltage).

Charging them back up on mains, we've only been able to get 1 to 82% and the packs 2 and 3 only to 77%. They will not charge more.

Pack 1 has 331 cycles and is nearing 2 years old. Pack 2 and 3 are on 594 and 593 cycles respectively and are nearing 3 years old.
I am of the opinion that these batteries are toast.

Any opinions on this?

36 minutes ago, Bl4d3 said:

Hi Everyone

So we've been experiencing some issues with our TheSunPays LiFePO4 batteries.
We have 3 x 4.8kw batteries and have looked after them quite well, using only the manufacturers settings and never going outside of this.

For the last couple of months though, we've had a problem. If the batteries dip lower than 25%, the voltage drops off massively and then we can never get it back up to 100% without TSP connecting to the batteries and resetting them.

Todays loadshedding caused an issue where we were on 50% at 10am and had 4 hours of loadshedding with little sun in Cape Town. The batteries hit 20% and within a matter of seconds dropped to 13% at 44v (cut off voltage).

Charging them back up on mains, we've only been able to get 1 to 82% and the packs 2 and 3 only to 77%. They will not charge more.

Pack 1 has 331 cycles and is nearing 2 years old. Pack 2 and 3 are on 594 and 593 cycles respectively and are nearing 3 years old.
I am of the opinion that these batteries are toast.

Any opinions on this?

Do you have access to the BMS data to see the SOH, the current Full Capacity as well as the actual Volts per cell and per battery.

Without this it is impossible to troubleshoot.

You need something like PmodbusTools along with a cable to connect to the RS485 or RS232 port on the battery and an USB port on a laptop

 

Edited December 16, 20222 yr by I84RiS

22 minutes ago, I84RiS said:

You need something like PmodbusTools along with a cable to connect to the RS485 or RS232 port on the battery and an USB port on a laptop

@I84RiSis correct, you need to download PBMSTools from the Tech Support page of their website and you will need to use the RS232-USB cable that should apparently have been in the battery box. This should allow you to connect a PC to the batteries to see what is going on. You may have an issue with unbalanced cells.

I see they don't supply the parallel battery cables with the battery, have you added them yourself? These are necessary when paralleling batteries for them to stay balanced among themselves.

Edit: I do see this note on their website: "It is not recommended to parallel an older battery with a new battery. The internal resistances of the batteries and the firmware may differ."

Edited December 16, 20222 yr by jumper

19 minutes ago, I84RiS said:

Do you have access to the BMS data to see the SOH, the current Full Capacity as well as the actual Volts per cell and per battery.

Without this it is impossible to troubleshoot.

You need something like PmodbusTools along with a cable to connect to the RS485 or RS232 port on the battery and an USB port on a laptop

 

I've attached 6 screenshots, all dated. 3 are from March this year when the issue first appeared.
TSP connected, reset something in PBMS and SOH was back up to 100%.
Same issue happened a couple weeks later, they connected and reset it. SOH back up to 100%

 

 

7 minutes ago, jumper said:

@I84RiSis correct, you need to download PBMSTools from the Tech Support page of their website and you will need to use the RS232-USB cable that should apparently have been in the battery box. This should allow you to connect a PC to the batteries to see what is going on. You may have an issue with unbalanced cells.

I see they don't supply the parallel battery cables with the battery, have you added them yourself? These are necessary when paralleling batteries for them to stay balanced among themselves.

Edit: I do see this note on their website: "It is not recommended to parallel an older battery with a new battery. The internal resistances of the batteries and the firmware may differ."

All 3 packs are connected to each other using parallel cables (standard cat5).
Before purchasing the new battery, we had confirmed with them that it is a match to ours, internally and firmware and they confirmed it would be ok.

Data from Solar Assistant

Just some more data. This was when the batteries dropped from 20% - 13% and the inverters shut down due to low voltage.
As you can see, there were no spikes in power draw. Voltage also dropped rapidly from 47v - 44v in the span of 10min

27 minutes ago, Bl4d3 said:

I've attached 6 screenshots, all dated. 3 are from March this year when the issue first appeared.
TSP connected, reset something in PBMS and SOH was back up to 100%.
Same issue happened a couple weeks later, they connected and reset it. SOH back up to 100%

 

 

All 3 packs are connected to each other using parallel cables (standard cat5).
Before purchasing the new battery, we had confirmed with them that it is a match to ours, internally and firmware and they confirmed it would be ok.

So it is likely that the SOH (and the Full Capacity) has dropped again?

This is probably being cause by some error in the BMS software as opposed to the actual cells being at the end of their life. 

By example, the BMS will have a threshold that will trigger an overvoltage alarm (say 3.6v for any given cell) and then another that will trigger an overvoltage protection (say 3.65v for any given cell). A normal functioning BMS will stop the charging whan an overvoltage protection is triggered, but I have seen examples (due to faulty software) where an overvoltage alarm ( the 3.6v in my example) will trigger an immediate reduction in the SOH (and the Full capacity) to whatever the remaining capacity is at the time the overvoltage alarm is triggered. 

So say there is one cell with a lower resistance compared to the others, this cell will charge the fastest and its voltage will rise rapidly once the battery enters the constant voltage charge phase (while the Volts of the other cells will not rise as fast). This cell might reach 3.6v while the battery is only at a capacity of 98Ah, which will mean that the SOH will be set to 98% (in a 100Ah battery) if this software error is present.

Resetting the SOH to 100% does not fix this problem as it will keep on reducing the SOH each time the alarm is triggered.

You will need to determine what is causing this SOH reduction. A good place to start is to download the history of the alarms that have been triggered from the BMS and look for a common theme between the batteries as well as the alarm that appears the most. This will likely be the cause.

Fixing it is a different issue where you will need the suppliers help. Maybe also ask if it is possible to update the firmware on the batteries to the latest available, this might just solve the issue.

 

Edited December 16, 20222 yr by I84RiS

9 hours ago, Bl4d3 said:

All 3 packs are connected to each other using parallel cables (standard cat5).
Before purchasing the new battery, we had confirmed with them that it is a match to ours, internally and firmware and they confirmed it would be ok.

That is good to know, comms are clearly working properly as seen in your screenshots. Also good to know they told you it would be fine to parallel them so they can't use that as an excuse.

As @I84RiSmentions it may be a problem when the battery is charging and a cell(s) is hitting the overvoltage alarm. The cells look perfectly balanced when discharging, but usually they are most unbalanced when reaching the top of charge. Might be a good idea to also take some screenshots of what is happening when the batteries are charging, there might be a major imbalance there causing somehow causing the SOC calc to be incorrect causing the big drop when discharging.

On 2022/12/17 at 7:24 AM, jumper said:

That is good to know, comms are clearly working properly as seen in your screenshots. Also good to know they told you it would be fine to parallel them so they can't use that as an excuse.

As @I84RiSmentions it may be a problem when the battery is charging and a cell(s) is hitting the overvoltage alarm. The cells look perfectly balanced when discharging, but usually they are most unbalanced when reaching the top of charge. Might be a good idea to also take some screenshots of what is happening when the batteries are charging, there might be a major imbalance there causing somehow causing the SOC calc to be incorrect causing the big drop when discharging.

So TheSunPays connected and recalibrated the system.
Unfortunately a cell in pack 2 and in pack 3 isnt looking too good and the batteries have to go in for assessment and repair.

Good news is they assisted within minutes of asking for help 

4 hours ago, Bl4d3 said:

So TheSunPays connected and recalibrated the system.
Unfortunately a cell in pack 2 and in pack 3 isnt looking too good and the batteries have to go in for assessment and repair.

Good news is they assisted within minutes of asking for help 

Sad to hear the batteries need to go in for repair, but nice to hear they provide good service. Good luck.