Rapid Battery discharge without apparent corresponding load?

[AndyPlatt]

Acting on a suspicion about the performance of my 9.5kWh GivEnergy battery, I set it to fully charge for an hour at 1am, for an hour on cheap rate, while quiescent overnight usage is low.
The attached graph shows what happened between 01:00 and 02:40hrs this morning doesn’t make sense to me:
01:00 - Battery begins charging from grid power, drawing about 3kW and goes from ~7% to 100%, in 45 mins (this alone doesn’t make sense to me for a 9.5kWh battery?)
02:00 - Once the battery is out of the 1hr “charge from grid” period I set, load is drawn from the battery again, which is then fully depleted over a period of just 40 minutes, with a pretty steady load from the house of about 200W.

I infer:
-Looks like the battery has way less than 9.5kWh capacity
-Seem to be getting much less out (<0.2kWh) than I put in to the battery (~1.5kWh)

I suppose the dashboard reporting could be badly wrong, but its quite a lot of detail that vaguely represents what I was expecting to happen at that period.

Maybe the battery needs recalibrating, but it was only installed (and calibrated) in May last year.
Thoughts welcome. Thanks very much,

[TX200]

Have you recently applied a firmware update to it? Some of the firmware is better than others at tracking the state of charge (SoC) percentage.

It does sound like a calibration could be a good idea.

Or if you haven’t done an update recently, maybe do that and it might do a calibration afterwards anyway.

[AndyPlatt]

Thanks TX200. I haven’t manually prompted any update, but weirdly, now I look, it claims to have last updated yesterday at 9pm…

I don’t see a way to tell it “recalibrate now”, so have scheduled a recalibration for tomorrow. I’ll report back if it changes anything.

[Eowaril]

My 5.2kw battery on the latest firmware is showing 100% charged after about 40mins too - today’s Peaksave Sunday charged less than 2kw between 11am and 4pm, because it reported full at 11:40am then used grid until 4pm, then (as yours did), quickly went flat before 5pm.

Ive tried the email contact form, and Twitter, and the phone lines to reach out about this issue, so if you have any luck, please let me know!

I have Winter battery conditioning enabled, and it is loft mounted, so should not be getting too cold to charge properly, so I’m running out of ideas…

[AndyPlatt]

Really pleased (and slightly surprised) to say that a battery recalibration has fixed it! The recalibration took 10 hours (!) from 10:00 - 19:30ish as you can see from this graph of the full day yesterday:

Note the weird sawtooth shape going on during the last few hours of recalibration is actually the result of my daughter coming home and switching an oil heater on…

Anyway, having gone away and had a good look at it itself, overnight behaviour last night looks like this:
(have just learned that “new users can only include one embedded image per post”, will make a separate post).

tbc…

[AndyPlatt]

Much more civilised.

I’ll have to keep a closer eye on it in future, maybe schedule a 6-monthly recalibration as a matter of course?