question

Hi @perma-batteries,

As a possible temporary work around, could you set the ESS mode back to Optimised (instead of Keep batteries charged), the SOC discharge limit to 90%, and then program a scheduled charge window to run every day for 23 hours to recharge to 95% (to recharge from the grid after an outage).

The Low battery alarm will be the battery disconnecting itself after the high voltage (or high current) alarm.

See if that corrects the alarms, and gives the batteries some opportunity balance (without approaching the very top end where a high voltage issue is more likely).

Hi Guy, thanks for the answer, will follow your advice, we've noticed that the system actually started to be faulty after we've upgraded to firmware 2.60 in Septembre.

We've switched to batterylife, SOC 90%, and we're going back to firmware 2.54 once the batteries have stabilised to switch back to keep batteries charged and see if it works fine again with the previous firmware.

Thanks !

Hi @perma-batteries,

We raised the charge voltage of Pylontech batteries by 0.4V in Venus 2.60. This explains why you're starting to see the symptoms after this new release. It is noted in the release notes too. For the full reasoning, see the original issue: https://github.com/victronenergy/venus/issues/536

Secondly, the voltage we use is still on the lower end of what Pylontech wants. We've had only a hand full of cases out of thousands of installations.

Third thing I need to mention: The high voltage spike is often a symptom rather than the cause of the alarm. When the battery activates its internal protection to protect a cell, it disconnects that module from the DC bus. The voltage measurement on the DC bus is then different from the real battery voltage, so that the voltage mentioned in the alarm message will not necessarily reflect what really happened.

You are 100% correct that it has to do with the balance of the cells. The battery ideally needs to cycle for the balancer to do its job, since balancing is most efficient during charging after some of the cells reach 3.458V.

For a battery that is in imbalance, it can take several days, even weeks before it comes back into balance. So this would be the first half of my advice, you'll have to cycle the battery a little.

Secondly, Pylontech will be able to provide you with the software needed to communicate with the battery on its console port. That will give you more insight of what is happening internally, and the data can be used by Pylontech to determine whether you may have a warranty claim.

I hope this helps.

Izak,

Thanks for chiming in and the extra details, we're going to proceed according to your advices and Guy's and will keep you posted about the results.

Cheers !

As a side note, we've noticed that even if we activate "Limit inverter power" , the current drawn by the US2000 will still be ultimately determined by the DCL and BMS and NOT overriden by the "limit inverter power" option, which is worth noting (-68A sudden burst from 2x US2000, inverter power activated at 1200W).

So my guess is that the limit inverter power function is only working when you've got non managed (ie : lead acid, etc...) batteries with an ESS....