Battery failing to discharge as programmed down to SOC 4%

21 comments started 2021-12-12 last 2021-12-22
GivEnergy Products
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#1 mjkelly5a

My battery has always been set to discharge to a 4% floor. the last 3 nights it has failed to meet demand from 10%, 12% and tonight it is 15%. So it has stood idle for some time until the nightly charge kicks in.

It is set to a 4% reserve I've checked.

Any ideas?

#2 judgepd

mjkelly5a I've had this same behaviour but always been told it's the battery calibration that is giving a misleading value. Maybe worth dropping support an email to check though.

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#3 andrew_bond

I had the same issue although not that dramatic - mine initially discharged to 4% or 5% but after a few weeks this increased to 7%. Eventually I noticed and recalibrated to fix it (although the first time made it worse - 9%); after the second recalibration it's back to 4% or 5% and seems consistent now. I'm getting about 8.2kWh in that range, so happy with that.

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#4 mjkelly5a

judgepd Can I recalibrate myself? What are the steps?

#5 hoggy

mjkelly5a
1: New Beta Portal > Inverter Card >Remote Control (Cog in Top Right) > Battery (Just below General) >

2: Where it says "Battery SOC Calibration" press the refresh arrow
This should change to Read Successfully & the drop down box to the right should say "Off"

3: Click Dropdown Box & Select Start/Discharging then click Arrow to right of box to send the command.

If you repeat step 2 then it should tell you what it's doing during all this but note:
This will completely discharge your battery & then fully charge again at whatever your current grid import rate is.

I'm surprised we have this control as it does seem a bit punishing to the battery (taking it to either end of its cell charge & discharge limits) although I'm on the old battery with no buffers - The newer ones have a fairly large bit of extra capacity to play with so not much of a problem.

(FYI - My portal kicks me out as soon as i try this so i need to login again. It then does the above fine. Not sure why but i have a lot of automations/API stuff going on which may be related)

#6 Woodstock

mjkelly5a I had something similar happen last night. Battery has always previously discharged to around a 5% floor but last night it appeared to fail to meet demand at 19%. Battery SOC showed 19% continuously through the night until at 09:09 this morning it dropped to 0% in the space of one five minute window! The inverter then kicked in and immediately started to draw 2975W from the grid until battery SOC reached 4% when things returned to normal and battery charging continued at a normal slow PV input rate. It was as though the battery SOC reading had stuck at 19% when the battery was actually still discharging (which allowed the battery to go right down to 0%) then suddenly the reading "unstuck" and showed the true value of 0% which caused a panic reaction from the inverter to try and get the battery back up to its 4% floor figure as quickly as possible!

AC-3.0 inverter. New 8.2kWh battery. System mode is set to minimise grid input/output.

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#7 mjkelly5a

hoggy They've turned off my recalibration and will initialise it tonight at 20;30 to meet my GO tariff.

It's only peanuts but there my peanuts! Just annoyed we never got a warning. Hey ho.

#8 judgepd

I'm starting to think that the recalibration process doesn't work for any length of time. Mine did a recalibration yesterday after the update and already it's starting to import at 7% instead of 4%. If the values on the portal aren't accurate then it quickly becomes pointless to look at.

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#9 mjkelly5a

judgepd Getting frustrated with it now. Mine is doing exactly the same. Set to 4% and stopping at 7%. I've reset it to 5% nothing! Back to 4% stays at 7% AAARRGGHH

#10 nwc469

I agree something similar happening here since firmware upgrade sits at 6 percent unable to change

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#11 mjkelly5a

nwc469 I ahve an answer back from support. It is a known issue and FW upgrade is being worked on.

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#12 andrew_bond

mjkelly5a Thanks for reporting (mine is also now stopping at 7% post-recalibration). I'll look out for the f/w update then!

#13 judgepd

Fingers crossed it won't need another battery recalibration! :-)

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#14 mjkelly5a

judgepd I'm afraid it will. From what I can see any firmware update needs to put the batteries in sync.

#15 Woodstock

Mine was working fine (discharging to 5-6%) until I upped the battery reserve capacity from 4% to 6%. It then stopped discharging at 8% and continues to do so even though I have reset the reserve capacity to 4%. When it was discharging to 5-6% the SOC graph line was a horizontal 6% with intermittent blips down to 5% as if rate of discharge had been cut to near zero but if left long enough it would have eventually got down to 4%. Now it is stopping discharge at 8% the SOC line is horizontal with no blips. It is as if it is now operating a "battery reserve" (sudden) cut off rather than a "battery cut off" (ever decreasing discharge) cut off.

#16 hoggy

Woodstock If you go to the remote control page (Inverter card, top right) & scroll down to "Percentage limits" do any of those match the 8% figure. (either battery reserve limit or cutoff % limit)
You may need to refresh the values by clicking the refresh button in either box.

#17 judgepd

I wonder if this is a sign of how quickly the battery calibration drifts. For example, last night, while charging, my battery went from 86% to 97% in 5 minutes (clearly not possible). After it was full it stayed at 100% for almost 3 hours (also not possible) before starting to drop as I would expect. Mine has been recently calibrated but it just doesn't ever remain calibrated for even a day or so.

#18 Woodstock

hoggy No. All the percentage limits are set to 4%. I have previously experimented with changing them to 5% or 6% but no higher.

#19 Woodstock

judgepd I am coming to the conclusion that there are two issues in play on this thread.

  1. The system not doing what it has been set to do.

  2. The system reporting not matching what it is actually doing.

Having one or the other makes it tricky enough to analyse what is truly happening but both together is making it nigh on impossible.

#20 judgepd

Woodstock This sounds like exactly what has happened to me in the past. You set the bottom limit to 4% (which internally equates to a set voltage) but then your battery calibration drifts and the battery bottom limit is the same voltage as it was but this now equates to a different percentage.

For me, my lower limit is set to 4% but in practice it will stop discharging at 7% (I believe the lower limit is still set to the same voltage but the mapping between voltage and percentage 'drifts' in some way). Over time this lower limit seems to get higher too.

Do I even make sense to me anymore?...

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#21 andrew_bond

My battery is also continuing to charge for several minutes after it reaches 100%, and similarly it discharges for a while before it goes below 100%. From a quick calculation it looks to be charging to roughly 103% as reported, and it stops discharging at 7% at the moment, so I guess it balances out - but it would be nice to have accurate reporting.