Battery charging changed yesterday and today.

We are on the Octopus Flux tariff so I have set a charge from grid period when it is cheap between 2 and 5am. We have a 5.2kWh battery so it didn't need the full three hours to charge., so I started it at 3am to reduce the time the house is powered from the grid. This is what a charge used to look like:

When the charge is less that 20% is charged at 1.8kW, then it switched to the maximum, about 2.7kW until it got to 90% and then it ramps down as it approached 100%.

The last two nights it has been doing this:

Now when it gets to 90 % it drops the charge current to 440W so it only got to 95% this morning as it started quite low. I need to move the start time forward but why has it changed? Anybody else noticed a change.

The inverter firmware hasn't changed since installation. on 20th Sept. Battery firmware is 3012 and I don't think that has changed but who knows?

Instead of changing the start time, you could just reduce the charge rate, so it charges slower and doesn't get as hot as a result.

Although not sure it really matters if it's charged half way through the time period rather than towards the end.

If it charges before the end it often starts discharging to the grid, so it is less than 100% at 5am, which isn't ideal.

Its behaviour is so complex it is hard to tell it from random. Every other day so far when it gets to 100% it starts to discharge back 95% at slow rate and cycles. Today it has flat lined at 100% even though it is discharging. And it shot up to 100% from 93% with very little charge power.

It seems like it has changed its mind where 100% is and now thinks it is over 100%.

@"TX200", I took your advice and charged it for 3 hours at 1.5kW and it looks a lot happier, thanks.