Battery power 'reserve' confusion

Hi all, I have recently had a 5kW inverter and 5kWh Gen 2 battery installed with enough panels to fully charge the battery every day since the installation. We discharge it by the following morning and the have minor grid import until solar starts to charge it again. I think I am getting the full capacity of the battery by looking at the input/output energy. The strange thing is that in the App the battery reserve is set at 18% and Power Reserve set to 'on'. If I try to change this it always sets itself back to the same settings after I press Save Settings. On the portal in the remote control (not changed any of these settings myself) The battery reserve % limit is set to 4% and the battery cutoff % limit is also set to 4%. Can anyone explain this misalignment. I also don't believe the battery ever carried out a calibration, although the GivEnergy operator told my installer this it would take place overnight or by morning. He obviously went home as everything was checked as OK with GivEnergy on the phone. The graphs of power/energy do not show a charge/discharge for the night after installation. Just a small blip of energy in the night but nowhere near a full charge or discharge.
Thanks in advance!

I am having similar issues. My initial theory was that setting the tariff to GO was somehow overriding my manual settings but I am not so sure it seems like a bug in the inverter software now.

I believe its not accurate in the mobile app so for the moment use the web portal. THe mobile app is being reworked and fingers crossed is not too far away

locked I have tried from both, mainly via the web portal

OK, the app is being re-worked and that's great. The reserve in the app happens to be the cutoff limit in the portal. I changed the portal 'Cutoff %' and the reserve changed in the app. FYI really, looking forward to the new app. Interestingly I would have thought that the battery SOC would have been the sum of reserve and cutoff limits added together. I guess the reason for the two types of control is because if the backup (mains off) is used the reserve % will discharge down to the cutoff limit %. My system is not correctly configured as the cutoff % is higher than the reserve %. However if I am correct then the amount of % for backup power may be the % reserve - % cutoff. Personally I would prefer if it all was in energy 'kWh' and simply leave this % stuff out of it. Maybe I will do some tests to find out exactly how it works.

Cutoff set to 4% (Default) Reserve se to 5 or more. Depending on how much you want to sacrifice for the event of a power failure. I have mine at 7%.
EPS is a mere 100W, so that 3% will do me an hour or so running the internet router and wifi

TheDragon (GivEnergy) The modbus API (givTCP) seems to suggest that the 4% reserve in the control panel is actually about 9% in real life. There are two readings. I've not been able to confirm this, but potentially it should be safe to discharge to 0% reserve and still have 4/5% remaining power in the battery. Sadly GE didn't respond to this enquiry.

jd I think this page describes the %age figures used. The bottom graph showing the actual capacity of the battery along the horizontal axis and the useable capacity on the vertical axis should make things clearer.

Tim It would be great if all these very useful bits of information were put into a manual and made available to users. Thanks for the link it helped a lot.

Looking at the link this implies that for say the current 8.2 battery you can only use 96% (7.87kWh) due to the 4% default reserve. But these batteries are advertised as 100% DOD so can you drop the reserve down to 0% and if so does this effect warranty in any way? Even at 0% the battery should have 15% of its true capacity to ensure it stays healthy. My Usage case will be to fully discharge and charge on a daily basis so do not really want or need to hold 4% in reserve. Anyone any experience of this? Thanks!

Kryten in my case its not possible to set below 4%. 4% is the lowest the slider will travel, I have the 5.2 battery. If you have the 8.2 battery can you slide to 0%? You don't need to press send to find out. I have a second 5.2 on order as I wanted to see how well it all performed before committing the extra cash. I am very happy with the system and it only gets better with upgrades so although it would be great to have everything at the start I am happy to see it improve with time and effort from GivEnergy. It may be that the 8.2 battery is actually higher than 8.2 allowing a full advertised 8.2 to be used while its a higher capacity in reality giving the protection you suggest is required for avoidance of over discharge. Just a thought.

Robert* I am awaiting install of 3 x 8.2 so can't test myself. The 8.2 are just over 10kWh in true capacity with 8.2 usable but then this additional 4% reserved confuses me. Is it 8.2 reduced by 4% The link posted earlier would indicate so. I really need to have access to the full 8.2kWh (minus inverter inefficiency) for my usage case.

Kryten I suspect it will become clear once you are running the system if the 8.2 has the 4% applied or not. Still if you have plenty of capacity and will not use it all, I suspect its better the battery is not either fully charged or discharged. As I remember from my time designing with batteries the life of the battery was somewhat dependent on the full charge level selected (final voltage) and how long it was left at that state. I believe some mobile phones now stop charging at 80% and wait until the amount of time it would take to complete to 100% (ready for when you normally use it) and start again at that time. I am intrigued as to the large capacity you are going for, are you expecting to transfer charge to an EV or something else?

Robert* I have a combined business/home premises and as such consume 30kWh per day excluding EV charging. Planning to use Solar in the summer but will relay somewhat on off-peak charging and more so durring winter. My Calcs are that 23kWh battery storage would just about cover it but if I factor in an additional 4% lost storage then im a bit short which is not a major problem just a bit annoying if the 8.2 battery is marketed as 100% DOD. My calc is (3 x 8.2) x 0.94 (DC to AC loss) = 23.1kWh. A further 4% reduction looses me about 1kWh of storage.

Kryten I'm impressed! Hope it works out as you expect. I believe 100% DOD means 100% usable, but some needs to be retained so it does not go below the minimum cell voltage so the statement is confusing from GE.

OK. This is an old converstation, but the link to the GivEnergy 'Battery capacity explained' graph shows what we see as a 4% Cutoff in the portal or the app is actually a 15% real reserve in the battery, as the battery is operated between 15% - 95% real SOC (corresponding to 4% - 100% in the portal). The reason for such limits is because Lithium Ion batteries degrade fastest near either 100% or 0% SOC (hence ideally if they are going to be unused for a time they should be left at 50% SOC). I presume battery reserve gives you control over the minimum amount of power you can get from the mains outlet on the inverter board? ie you can't set the reserve to be less than 4%, because come what may you shouldn't be able to discharge the battery below this, but you can set it higher (say to 7%) which would give you 3% in case of a blackout and the mains shutting down? So that mains outlet can power your phones and fridge.

Captain Scarlet 99 battery reserve is useful for those with the EPS circuit wired up. It reserves battery for such cases as mains failure. Although personally I'd rather use my investment than always reserve a bit of the battery just in case.

Battery cut off will be removed in future, deprecated feature.

Plus I think the batteries are Lithium Potassium, might not be subject to the usual leave at 50% charge advice.