Interesting issues with Sol-Ark 8K and SOK rack of LiFePo batteries

[StevenC]

I just brought up a new diy solar system with a sol-ark 8k, a five battery rack of SOK LiFePo 48 volt batteries and 6.8k of solar panels. The system is operating in a simple "off-grid mode" powering a critical loads panel until my electrician can replace my very old main panel after which I can install the sol-ark CT sensors. I have communications implemented between the battery rack and the sol-ark. All was well at first. I assumed that the battery charge and discharge parameters would be set based on whatever the SOK battery BMS communicated to the sol-ark. However, I started to have battery shutdowns with a OVP message. The absorption and float voltages had both been set to 57.6 volts - the latter different than what CC specs. The equalization time was also set to 30 minutes. I could not change these values along with the max charge and discharge rates. Once I began having the OVP message on one or more batteries and I could not change these values, I disconnected the comm cable between the sol ark and battery rack and then began to step down the float voltage and absorption voltages disconnecting and resetting the batteries on each iteration until the OVP errors stopped occurring. I am now running the sol ark with the float and absorption voltages at 55.0 and 55.4 volts. Equalization time is set to 0. I did change the %v parameter to %charge since I had found on a previous system that voltage was not a reliable indicator for SOC. Both my maximum charge and discharge rates are set to 185 amps. Anybody else have these kinds of issues? Is the SOK to sol-ark comms working for you?

Steve

 

[MuckMuck]

I am also having some strange issues with the SOK's (5). I have a 15k and set the SA to lithium (00) as instructed in one of Current Connected videos but can't read cell details from the SOK's and I have a triangle with an "!" in it. SA support suggested that I change the battery setting to Lead Acid and that they have some SOK's that they are working on adding SOK support. Now I am trying to figure out why the batteries won't charge even though I have setup "time of use". When you change any of the "Time of Use" setting and click "Save", does your inverter drop the Load and reboot?

 

[RCinFLA]

If battery cells get out of balance BMS will tell inverter to back down charging when BMS detects a cell getting close to overvoltage in an attempt to avoid a BMS charge shutdown.

 

[HighTechLab]

In communication mode, the voltages are not going to be the same as we suggest for non communication. It goes based on current when communicating, and is dynamically adjusted based on a lot of different conditions. If a cell is too high it tells the inverter to stop sending current, rather than saying to target a lower voltage. When batteries are new, it is common for them to have overvoltage protection on the battery as the cells come into balance. The triangle with the ! Is only telling you the inverter stopped charging because the battery told it so. That way you’re not trying to go through the settings on the inverter and figure out what’s wrong with the inverter when in reality it’s just doing as it was told.

As the battery does its thing and balances out, you would not hit ovp on the battery anymore - by lowering things down as you did, you have reduced the bms’s ability to balance the cells out and this can affect your capacity over time.

 

[Edd]

In communication mode, the voltages are not going to be the same as we suggest for non communication. It goes based on current when communicating, and is dynamically adjusted based on a lot of different conditions. If a cell is too high it tells the inverter to stop sending current, rather than saying to target a lower voltage. When batteries are new, it is common for them to have overvoltage protection on the battery as the cells come into balance. The triangle with the ! Is only telling you the inverter stopped charging because the battery told it so. That way you’re not trying to go through the settings on the inverter and figure out what’s wrong with the inverter when in reality it’s just doing as it was told.

As the battery does its thing and balances out, you would not hit ovp on the battery anymore - by lowering things down as you did, you have reduced the bms’s ability to balance the cells out and this can affect your capacity over time.

I recently checked the BMS records for my three months old SOK server rack batteries and found high numbers of OVP for the batteries: one is 102 and the other 308. Is it normal to have these OVP counts for a three months old batteries? And I've noticed that solar charging does not start on following day unless the system is powered down and restarted. After restart solar charging works for a day with no problem, followed by utility charge at night. But next day there is no solar charging again.
I have two brand new (3 months old) SOK 100Ah 48v batteries connected to Growatt 3000 SPF LVM-48 inverters configured in split phase with 2550 watt of solar panels wired to one of the inverters. Using "user" settings for the batteries (57.6 absorption, 55.2 float). Using solar priority SOL.

Any suggestions would greatly appreciated.

Thanks in advance.

 

[HighTechLab]

Is it normal to have these OVP counts for a three months old batteries?

On its own, it's not abnormal...the count does go up quite a bit during the initial balancing of the pack, but once things are in balance it will be triggered less and less often. If however, it is paired with significant cell voltage deviation after months of use, then it would be a good idea to contact our support to further troubleshoot.

After restart solar charging works for a day with no problem, followed by utility charge at night.

Certainly an inverter problem - I have one other customer with a growatt that had the exact same issue and we troubleshooted for a couple hours and pinned it to the inverter's firmware.

Thanks!

 

[Edd]

On its own, it's not abnormal...the count does go up quite a bit during the initial balancing of the pack, but once things are in balance it will be triggered less and less often. If however, it is paired with significant cell voltage deviation after months of use, then it would be a good idea to contact our support to further troubleshoot.


Certainly an inverter problem - I have one other customer with a growatt that had the exact same issue and we troubleshooted for a couple hours and pinned it to the inverter's firmware.

Thanks!

Thank you for your response!
I'll try to contact Growatt.