Frequent sudden drops from ~7-10% SoC to 0, then “charge” up

Hi All, I have an AC3 and 9.5 battery. I am seeing frequent sudden small drops at the low end from ₇-10% battery to 0, followed by an apparent “charge” back up to the 4% reserve. I know the latest BMS 3013 (which I am on) does calibration at the top and bottom end, but I am seeing this almost every time I run the battery down. I’ve seen it something like 2-3 times per week, as I’ve had a period of high use after sundown. Is this behaviour normal? Shouldn’t the calibration stop this from happening? Attached a few examples.

I can't help other than to say I am experiencing the same. This morning I was on 22% and when the sun started to charge the battery, it dropped to 13%. Odd. I'm on the same Battery firmware as you with an 8.2kWh battery.

Thanks. Curious to see if others are having the same behaviour.

Boffinboy Feels like the BMS isn't learning/remembering the top and bottom thresholds? Ask @TheDragon (GivEnergy)?

I’ve been experiencing the same issue. I’d flagged up some oddity with 3013 whereas I’d found 3012 rock solid for me.

Then last night it started doing exactly the same as you described.

I contacted support this morning and got reverted back to 3012.

Tim

Thanks. Hoping @TheDragon (GivEnergy) may spot and share if it’s a known issue

Boffinboy Doing this every day, is not normal. periodically yet it can self correct

TheDragon (GivEnergy) thank you for looking. Mine was a number of times over a period of about 10 days. It looks like others are having something similar more frequently. I’ve not ended up at that low charge recently so haven’t observed it.

Even being back on 3012. Mine kept doing it yesterday. Would crash to zero from around 4% then charge back up to 4% and then repeat. Was driving me nuts yesterday.

Force charged up to 38% just to give it some peace.

Continuing to see this semi regularly, also from higher SoC. I had understood the calibration of 3013 should stop this but it doesn’t appear to be working fully effectively. Any resolution is sight?

I had to revert back to battery firmware 3012 because 3013 did not allow the setup to work. The battery just completely drained and died, needing repeated visits from GE to fix the system.
GE gen 2 9,5KwH battery with Gen 3, 3.6KwH inverter

I now see the following:

The battery dropped to 6% (all good) and then without any PV available (night time) and without any import from the grid (confirmed also by Octopus separate grid consumption logging, not the data from GE), the battery managed to charge itself to 17% over the time you see above.

Completely impossible, yet that's what the BMS is reporting and even with version 3012.

JMA it didn’t charge itself magically.

The system, when idle, realised the battery had more charge in it than it thought it did.

It therefore updated the percentage to a more accurate value.

It is called a SoC correction (SoC is state of charge).

TX200

In my mind, SoC means "Estimated Charge Level". 🙂

The correction is often referred to as OCV (Open circuit voltage) and, as you say, is perfectly normal.

Rubikcube yes OCV is one of the corrections, there are other corrections built in which don't use OCV.

(OCV being disconnect the battery when it's been idle for a while, measure, reconnect, update SoC).

TX200
Thanks for that explanation, to me that makes perfect sense, but apparently not to the GE technician who is troubleshooting amongst others this phenomenon for this installation (there's other more serious things going on such as the battery completely draining itself dead and not coming back to life until a technician comes to the site to fix things and the battery refusing to charge from the PV - not this topic) . The GE technician is asking the installer whether the site has any other "power generating sources" other than the solar panels and the grid. He's thinking there might be another power bank, an emergency generator and/or EPS. There's none. He's also seeing that there was no PV power and also no draw from the grid and is trying to explain the above phenomena by a "real" power source charging the battery, he's not trying to explain it as an SoC correction. Looks like there's a disconnect in opinion as to what is the cause of the "correction" from 6%->17%.

JMA it's a little worrying some of their staff don't understand the new firmware. But I guess the firmware is pretty new. And so might some of the staff if they've grown the business quite a bit since the energy crisis.

Other issues, common with installers, seem to be

1. putting the grid CT clamp the wrong way around or on the wrong wire. Which will cause import to look like export.
2. Connecting the other end of the CT clamps in the wrong ports. Perhaps connecting grid CT to the solar etc. That gets really confusing when you look at the graphs. Not sure this is likely to happen with an AIO and gateway, think they're wired differently.
3. Not securing the WiFi network properly as per the guide on the KB site. Thus an open relay to your house broadband. Eeek!

Also making sure the units are up to date with the latest firmware - not sure if that's their responsibility, but given the bugs in the earlier firmware they'll have a much easier time supporting the kit if they do the upgrades!