Random battery charges

[AndrewCurrall]

I have (in the mode scheduler), my battery set to force charge between 2 and 5 am (to take advantage of the Octopus Flux rates), and, because it's winter and I don't have a lot of battery capacity, to force charge again between 2 and 4 pm up to a maximum of 60%. This was working well for about a week and a half.
However, a few days ago, while it continued to charge at the specified times, the battery also started drawing from the grid to charge itself at seemingly random times of day: on three successive days, once at midnight, once around 8am, and once around 8pm. On no occasion was the battery close to its specified min (15%), and on every occasion it charged up to exactly 60% and then stopped. Yesterday, it then proceeded to stop using the battery to power the house entirely, and the battery stayed on 60% all day. It reverted to normal behaviour at 5 am this morning after the nightly charge.

Any clue what's going on here? Is the mode scheduler buggy? Anything to do with the cold weather (but then why exactly to 60%?)?

On a related but less worrying note, I observe that in the 2-4pm slot, the battery does indeed draw from the grid to charge up to 60% and then stop drawing from the grid to charge more. However, during that time, it won't discharge the battery to power the house at all, even if the battery is well above 60%; and it directs all solar generated to the battery as well, again, even if the battery is over 60%. I would ideally like it to revert to normal behaviour if the battery is above 60%, or at most allow a small buffer (e.g. 65%). I don't suppose this is possible?

[Will]

Morning,

Had a similar post yesterday, this might help you but if not let me know viewtopic.php?t=1631

[AndrewCurrall]

No, I don't think that helps. I certainly had noticed that the battery charges slower when cold, and indeed it often doesn't fully charge between 2 and 5am, but that's not a big problem. I'm worried about it charging up when it shouldn't, not that it doesn't charge fast enough when I've told it to.

[Will]

Random charging is normally the battery doing a maintenance up top to keep the battery warm and within the low temp cut-off.

[AndrewCurrall]

Ah, OK. If that's a thing, then that's probably it, then- it has been very cold. I'm just puzzled by it always stopping at 60%, which happens to be the max charge level I've set for the force charge 2-4pm.

[Will]

can you share a graph from https://www.foxesscloud.com/ of the charge window. What is your charge rate, it is stopping at 60% or simply can't charge past that % within the time allowed. If you increase your time window does it charge past 60%?

[AndrewCurrall]

It works normally 2-5am and 2-4pm when the force charge is in effect. It doesn't always get to 60% in the latter period (I've set it to go up to 100% for the night charge), but that's fine. It's the random ones where it looks like it charges up to 60% and then stops.
I can access that site (I'd been using Fox Cloud 2 on my phone to date) and view graphs for the last few days, but while they show the charging period, they don't actually seem to show the battery's level of charge over time (the site shows the current battery charge level, but only that). Also I can't figure out how to share an image via these forums anyway.

[dorkypark]

I have also been affected by this issue in the last few days. I have a force charge period from 02:00 to 05:30 and min SoC of 15%.

On 8th January, the battery unexpectedly charged from about 19:45 to 22:20. It reached 37% and then immediately started discharging.

On 10th January, the battery unexpectedly charged from about 23:45 to 05:40 (on 11th). It reached 64%, held it at that level (i.e. pulled from the grid instead of discharging the battery) until the solar kicked in and charged the battery to 100%, after which it started behaving normally.

On 12th January, the battery unexpectedly charged from about 01:00 to 10:45 when it reach 100%. It held it at that level without discharging, all the way through to 13th January at about 14:30 when it started discharging.

While it has certainly been cold during the last week, the forced charging periods, charging levels, and preventing discharge seems rather random and not necessarily correlated to when it is particularly cold. The system otherwise appears to be working fine.

[Dave Foster]

It is the effect that cold weather has on batteries, Will has updated his video recently which covers this very well https://www.youtube.com/watch?v=nDAw0KAYvcE

[AndrewClarke]

Thanks, Will and David; very helpful.