Physically disconnecting a battery

A few days ago when it was cold overnight my primary battery (in the loft) decided to shutdown, I've attached the battery data, it was discharging at the time, so should have been warm enough and it's not the first night it's been cold.

My secondary battery appears to be full and functioning properly, apart from the fact that I can't use it, I can turn the primary on with the little button on the side but the status light goes to red.

Tried calling GE and spoke to 'Rachael' and asked for a human to call me back, also emailed them. I had this happen when I first got this system, before Octopus Cosy existed and I was just on a standard variable tariff so there was little point in using the batteries at the time. But back then both batteries shut down, one could be reset remotely by GE as it would turn on, the other one needed a technician to come out (2 week wait), but at least you could get someone to speak to on the phone.

I'm pretty sure that GE could reset my primary remotely and that would sort it. However 'Rachael' suggested gently warming the area and it should start to work again, it's been over 0 degrees for nearly 24 hours now. I've tried rebooting the inverter, turning both batteries off and on again physically, shutting down everything with the isolators.

My next thought is to disconnect the primary and bring it down into the house to see whether that helps, but I'm not sure of the procedure, do the wires need to be done in a particular order? Do they just pull out when you unscrew the plastic sleeve?

Assuming you don’t have the ring terminal connections on your battery and you have an orange plug, you shouldn’t be unscrewing the battery terminal plug, it just clicks in, but it has a safety latch so you have to push the clip in from the side and pull back at the same time. It is a bit fiddly though so may take a few attempts.

Make sure the inverter and battery are both turned off first.

The battery is physically heavy.

If your battery is in the loft then you’ll almost certainly need some supplemental insulation in the winter as once the battery cells reach 0 degrees they won’t discharge, and below 10 degrees the charging rate is affected. Kingspan, an old duvet etc will all work

Its the battery cells inside not the ambient loft temperature

geoffreycoan Thank you Geoffrey, I have attached images of my battery connections. Assuming that these disconnect easily and safely, could I swap the cables so that the secondary is the primary whilst I bring the primary down to warm up?

Yes I did wrap them in spare rock wool after that 1st incident, but ever since I've been on Octopus Cosy they'll always charging or discharging when its cold due to running the heat pump so have left it off. I read that winter protection can mess with the single memory slot on the Gen 1 for charging in the cheap periods?

These are Gen 1 and require opening the case and unscrewing inside which I don't think an end user should be doing. Changing the master/slave order will also require changing dip switches and again I don't think that is something end users should be doing.

pwdst That's what I was afraid would be the case, I don't feel comfortable doing that.

As pwdst says, these are gen 1 batteries and the black cables go through the grommets onto screw terminals inside the battery. You would have to take the cover off and start unscrewing the cables, no easy plugs to remove, sorry

And yes, winter battery conditioning if it kicks in will write to charging slot 1, so if that’s all that’s available, it will overwrite whatever charge you had planned.
I’m guessing your battery is relatively small capacity. It might be worth you setting a lower charge rate so that it charges for the entire Cosy cheap period rather than charges for an hour or two and then sits idle, getting cold.

If it’s in the loft I think you should insulate it. My loft drops to only a few degrees C

geoffreycoan Yes they are 2 x 2.5kWh, I use RubikCube's android app to charge, will have a look to see if I can have a slower charge rate per slot, not a problem in the 10pm to midnight slot as charge rate is 2.5kW, but could lower it for the morning 4am to 7am slot. I've gone back to wrapping them with rockwool and will do so going forwards.