Batteries failing to supply power when they hit 35%

I have two 9.5kw batteries that are charged early morning up to 90%. Throughout the day they work fine, but recently, when they hits around 35-37%, they stop supplying energy to the house.
The timed discharge settings in my app runs from 00.30am to 23.59pm, and battery option is set with an operating range of 4% to 96%.
I have tried rebooting the system, switching all trip switches off and leaving off for 10 minutes, but it has made no difference.
I tried calling GiveEnergy, and the bot said an engineer would call, but that has not been the case!
Any ideas?

It sounds like it might be worth scheduling a calibration from the Portal. The calibration will take the batteries down to completely empty and up to 100% to reset State Of Charge (SOC). Therefore you might want to schedule it at a time where you don't mind doing a full import.

Randall74 You could have a reserve set somewhere, though that should always stop at exactly the same SoC. The obvious one is the reserve value itself - you've checked that, but it is possible for app and inverter to get out of sync, so it's worth setting it to something else, then back to 4%, to make sure they're in sync.

The less obvious possibility, depending on firmware version, is a minimum discharge level set on one of the discharge timers - even when timed export is off, these seem to take effect during the configured window, so worth checking that either all the discharge timed slots are empty, or the discharge level is 4%.

(Out of interest, why do you have the timed discharge set up? You're asking to pause discharge from 00:00 to 00:30. Do you charge from grid during that half-hour, or is that to allow the cells to rest to better track SoC, or something else ?)

If you have set a forced discharge (export) slot to export to 35% in the past, then even if it is disabled it will act as a floor to the discharge level. Try changing any discharge back to 4%, or reset to defaults and reprogram the charge slotss.

I think the app tends to hide discharge slots it thinks are unused - better to check the remote control page of the portal, which gives a more direct view of the registers.

pwdst Thank you for the reply. How would I scheduling a calibration from the Portal?

DD Thank you for the reply.

PaDav6 The export has always been set to 4%, but I will try changing it as a test. Thank you.

Randall74 My Inverter -> Remote Control

Find the section labelled "Battery" and then under there should be "Scheduled Battery Calibration".

Randall74 Just re-reading, I had missed that it's two batteries. I only have the one, but my understanding is that it will stop discharging as soon as one of the batteries goes empty. Ideally, the two batteries would stay more or less at the same SoC, but they can drift. Can you see whether the individual batteries have similar states of charge ?

Randall74 I have two 9.5kw batteries that are charged early morning up to 90%.

Any reason to stop at 90% ? Going to 100% might allow the BMS to track SoC more accurately. It can do cell balancing at the top end - not sure if that improves balance between battery packs.

DD I have the same problem with my 2 x 5.2 kw batteries not balancing properly. Charge will stop when the first one reaches 100% and the 'system' capacity thinks it's 100% but the second is still at 90%. Same problem on the way down but worse, it stops discharging when the 'system capacity' says it's 4% but the individual battery capacities can show 20 or 30% and they are not balanced either. Fully charging and discharging makes no difference. Battery firmware is on 3015 but I'm reluctant to upgrade to 3020 due to higher fixed drain and swapping one problem for another!

Beebod Does charging at very low power when one battery gets near the top make any difference ?

The system does automatically back off the charge current as it approaches full but the 2 batteries don't charge at the same rate and I'm not convinced there is any balancing going on. As soon as the first battery reaches 100% the system stops charging to prevent any over-charge and it just sits there, the batteries don't re-balance and continue charging. I believe the % capacity readings are not terribly reliable but I can see that the battery voltages are also different. The interesting thing is that when they are charged from apparent 4% to 100% the power used seems reasonably close to expected so it could just be bad data being reported or inherent calibration problems.

My Gen 1 batteries have the 3022 firmware and Gen 3 4010 - they drift a bit +/- 3% when full and about 7%+/- when about 25% full...I would definitely update firmware

AndyZ900rs Have you noticed an increase in Base Load consumption since you upgraded to 3022 and 4010? I gather there was a change to increase the base load in order to speed up the time the inverter took to kick in and a few folks have noticed the drop in efficiency due to the continuous higher battery draw but I'm not sure how big the impact is. Similar to yours, I have Gen1 Batteries (2015) and Gen3 Hy3.6 (409)

Beebod Interesting; where did you read about the ‘base load’ increasing with the new firmware?

I can’t say I’ve experienced this personally…

Beebod
No I have not noticed anything in this regard

Beebod that was inverter FW not Battery. And only really noticed on Gen 1 which was slow to respond. GEN2 onwards already worked as per fast response code by default.