Battery Charge Power 2.7KW instead of 3.6KW

For the past two days i noticed that my battery is charging at 2700W while few days back it was the normal 3.5KW.

I have checked all the settings and the registers are correct at 3.6KW.

Has anything changed for such behaviour?

Check your battery (cell) temps. GE have been meddling with throttling charge rates and it starts at a surprisingly high <20'c

Is the battery outside? Could it be the cold weather?

It’s in the garage and it does seem to correlate.

Never had this issue last year, how to fix this?

deepanshus Never had this issue last year, how to fix this?

Heat the garage/insulate the battery or live with it I'm afraid.

If the battery still gets to 100% in the off peak hours then probably no worry.

A gentle charge is better than a full speed charge, kinder on the kit.

Plus you can discharge slowly first to warm it up if it ever gets too cold to charge. Doing it slowly keeps it warm for longer, less chance of it getting too cold.

There are topics on here about insulating the battery (don't insulate the inverter!) if you use the search hopefully you'll find some examples.

Mine has recently dropped to 2.715kW. Not worried as it still charges the battery to 100% during the cheap rate

Thanks all, i am not sure why i didn't face this issue last year, i am planning on getting this 50mm board and covering up the battery on all 4 sides and will make it so that its easily removable so that i can take it off in spring.

Any specific points i should be keeping in mind while i do this?

TerryWagstaff i also realised, lower temp will not only reduce the charge rate but will impact the capacity in long run. so it's better to get some sort of insulation

deepanshus Thanks all, i am not sure why i didn't face this issue last year

GE changed the way the battery/inverter firmware operates. They're not exactly being open about why they did this (or even that they did it at all AFAICT), my personal opinion is that they're seeing a LOT of batteries with cells diverging excessively on charge rates above 3kW and this ameliorates/hides that.

Edit - you'll probably be fine with 25mm PIR board if the battery is internal. That's the equivalent of about 50mm of rockwool and 25mm board is a lot nicer to work with.

Edit2 - also please don't get Kingspan, they're an utterly corrupt company involved in the Grenfell fire.

Edit3 - also with the 25mm board you can double up/remove thickness if required using velcro.

Has anyone built an insulation box for their battery and posted the results (improvements) in battery temp? I’m tempted to do so, but at the moment I haven’t seen any drop off of performance from my batteries even though they’re in the garage and the cell temperatures have dropped to around 15 degrees

geoffreycoan Has anyone built an insulation box for their battery and posted the results (improvements) in battery temp?

I think there were a couple of threads last winter (which may have started during winter 22/23) but finding the relevant posts is a different matter 🙂

If you're still on 3015 then that doesn't reduce charge/discharge on the G1 inverters above 10C.

This is very frustrating, i have covered the battery in blanket and the temperature never falls low but even when it drops a little below 20, the battery charging gets restricted !!

the problem is that now my slots for agile charging will not be sufficient to top up the battery fully !! it cant be charged fully in 3 hours at this rate :-(

they should have a better threshold for throttling the charge and it should pick up once the battery is warm, like it is now, but it still charges at 2.7Kwh instead of 3.5Kwh

deepanshus Your battery cell temperature is probably lower than this, I think you are looking at the battery BMS temperature which is on the motherboard and warms up comparatively quickly when you start charging or discharging the battery. The battery cells warm up with use, just slower.

deepanshus while it's not ideal, perhaps do a low-power precharge before the main event. So while it might not be the very cheapest power, if you're only drawing 500W it won't cost much. But might warm the cells up so they're ready to charge faster when the price drops.

DD spot on. And another alternative, if there's anything left in the battery, a full speed discharge - as I think discharge can operate 10°c lower than charge. So it'll warm it up ready for the charge.

It's a pity there's no way to duct the warm air from the inverter to the battery.

This issue was introduced with firmware 3017. Asked to be rolled back to an earlier version.

DD yes, absolutely spot on, that's what the issue was, cells were at 19 while the Battery BMS was at a higher level that i was seeing on the dashboard. Now i have added cell level details and it makes it clearer.

However the threshold for 20degrees is still very high IMO, but the hack of charging/discharging for a bit to raise the temp works like a charm !

DD come to think of it, this would be a perfect addition to the BottleCapDave Octopus Agile integration, an option to pre-charge or pre-export (depending on SOC) for 5 mins before hitting the slot ! It can be called as "pre-conditioning the battery" .. very interesting suggestion.

I notice I now have this problem too since I updated the firmware to 3017. The inverter is set to charge and discharge at 3600W but it now seems to be running at around 1750W for both. I read above that a slower rate can be kinder to the battery, but is this too low? Why is it no longer charging at the full rate? Does this mean I'm drawing from the grid at peak rates when I could be using cheaper power (Octopus Cosy tariff) stored in the battery? I'll attach my readings from yesterday, first really cold day, so the ASHP kicked which prompted me to take a good look at my readings! (but I did check this drop in rate happened earlier when it was warmer too) Any thoughts? Should I raise a ticket with Giv?

Ange I had got the impression that it was only charging that would be throttled when the battery was cold - discharge wasn't affected.

I've adjusted my charge rate down to 3kW ( AIO ) with the colder weather. Will probably tweak it down further to spread the charge over a longer period overnight.

Tenkaykev I've throttled discharge power down for now - cold days mean HP is absolutely guzzling power, and if the battery has no chance of lasting very far into the day, may as well let it run down gently with a little dignity.

Ange I had the same problem a couple of months ago. It turned out to be a faulty cell in the battery. I would contact Giv and get them to check it. They replaced my battery.

I have noticed today with the battery reporting 14 degrees it was very slow to respond to demand which led to me pulling a significant amount from the grid during Agile peak. It may not be the first time as I happened to be looking at it as the grid was pulling 2kW plus.

Tenkaykev I've adjusted my charge rate down to 3kW ( AIO ) with the colder weather. Will probably tweak it down further to spread the charge over a longer period overnight.

I did the same on mine, restricted charge to 2375W. That way, it charges during entire cheap window (6 hours). Helps in cold temperatures, as battery is never idle, right after end of charging period it begins discharge for entire day.

Ange Just to update, I went back to my installer to contact Giv (seems like the only route), they agreed there was a problem and have updated my firmware to 3018, all now working as it should 🤞😀

Ange Do you think they have removed the throttling of charge due to low temperature in version 3018 firmware then?

buggsc other people have reported no, its in 3018, but 3019 has some ‘smarter’ charging throttling, but guess it’ll be a while before we see that BMS version

It was in 3017, and I was updated to 3018 to "solve it", but it still has the throttling to about 60% of max pn my gen 1 5.2kwh battery.

Was there an official announcement that GE were doing this? I cannot find it on any of their marketing for new batteries, and GE Support/Engineer appeared oblivious to it when they swapped out my battery end of last year.

They also introduced the winter conditioning setting in the app, but so far it is not mandatory, even though app says that it helps prevent battery damage. It is not mandatory, but if you choose not to set it (or don't know about) will it be taken into account in a warranty claim?

Karcsi Was there an official announcement that GE were doing this?

I don't think they've ever officially admitted doing it.