I know there are previous posts regarding this, but couldn't find them...
Last night our battery went from indicating about 1% to 100% almost instantaneously. Now showing as discharging.
Is this a portal/inverter data error, or actual behaviour?
Can/should I do anything to reset the system/data?
What hardware/firmware? Has anything changed recently? In previous posts, you've mentioned HA, Octopus R&D, WonderWatt - are any of these still active ? Is the battery particularly cold at the moment ?
What triggered the charge at around 9:30? Was it spontaneous, or do you have a timed charge set up for then?
It mght be useful to include the battery voltage on the graph - that's a weak proxy for SoC.
I can't remember if there's a way to access the individual cell voltages from the portal - I think I did stumble on it once, but couldn't find it when I was looking the other day. If not, and if you use Android, the @Rubikcube inverter monitor app can show the instantaneous values. Otherwise, I believe there may be a third-party IoS app that can also do lots of interesting things ?
There's no scale for the power consumption, but I assume the charging energy is a tiny fraction of the battery capacity. What is the history of the battery prior to this - have to assume it wasn't really empty when it reported it so. Has it provided the expected amount of energy since it was last at 100% charge ?
DD Short answer to all your good questions/comments - nothing's changed recently!
No timed charge or anything (that I'm aware of).
Battery not particularly cold.
We've had very little sun recently, so battery was cruising along at nearly empty for several days.
I'll look at your suggestions.
My main concern is that the reported battery state is incorrect. It's now showing what looks like normal trends with current usage and solar input - but is its baseline correct? I
James L We've had very little sun recently, so battery was cruising along at nearly empty for several days.
From what I've heard, people who regularly charge up to 100% and down to empty tend to have less trouble with random SoC jumps. LFP chemistry is such that voltage is very flat over most of the range, so it's hard to estimate SoC from just the voltage. The only other option the BMS has is to measure energy in and out and try to interpolate. Letting it visit both ends of the range from time to time help with this. Recent firmwares do try to do some introspection when load is low (possibly even pausing completely) to try to get a firmer estimate of SoC.
Many here have a ToU tariff and charge the battery overnight. I take it you're not doing that? I've done more reading on EV batteries than on LFP batteries, but the advice there tends to be to try to keep them betwene 20% and 80%, and that small cycles around 50% are best for battery health. (Charging overnight also avoids letting the battery get too cold.) LFP chemistry is more tolerant, but the same heuristics may apply.
I have a friend who also avoids charging battery from grid, on the grounds that cycling is bad. But I suspect leaving the battery close to 100% (as he does in summer) or 0% (as he does in winter) is probably equally bad. The battery will have buffers, so it's not true 0% / 100%, but still...
Anyway, I'm rambling.. what I'd do is use the battery as normal as it runs down to 0, then give it a relatively slow charge back up to 100% (doing it overnight will be friendly for the grid, and good for the temperature, even if financially neutral for you. Or when carbon intensity is low.) Even though the battery can tolerate charging at 3kW or so, it's probably kinder to be gentler, with a max charge rate of 2kW or even less. [I use a script to set overnight charge rate to whatever will take all 4 cheap hours to complete.]
Check that the recharge took in about as much energy as you'd expect. Then take it from there.
DD Thanks for the thoughts.
I haven't been doing anything special apart from leaving the battery on eco mode. So probably time to be a bit smarter with how we manage it.
I upgraded the firmware last night, and this resulted in the battery recalibrating - so let's see how things pan out now.
Just to add to the mix, I've now signed up for Intelligent Flux with Octopus - so that'll change the management/behaviour of the system anyway!
James L
Look closely at Octopus Agile. I've just switched from Flux and am saving 50-60%
johnsherman agile presumably requires fine control via an external agent to make it viable. Home Assistant or one of the cloud-based ventures.
Intelligent flux might suggest OP doesn't currently want to get too involved in actively managing the system?
DD
On Agile I've disconnected from the 3rd party now and just set the Inverted to Eco and forced charge from 0100-1600.
In my all-electric house this resulted in my paying 71p for 46kWh of electric on Christmas Eve 😊
