Home Assistant Energy Dashboard Charge kWh reliable?

martindell · Mon Oct 17, 2022 5:13 pm

I have 7 x HV2600 batteries, just charging overnight - no solar. Each has a nominal 2.56kWh capacity
In theory, that's 17.92kWh of battery capacity - a useable 16.1kWh assuming a min SOC of 10%.

On days when the battery discharges to 10%, Home Assistant shows a subsequent charge to 100% of no more than 13kWh
I don't understand why the battery isn't drawing a charge nearer 16kWh.
I understand there'll be some round-trip losses - but not enough to account for a 3-ish kWh difference.

Am I missing something? Are my assumptions incorrect? Does anyone else have a similar installation with different charge numbers?

I've raised this with FoxESS support but wanted to check in here too.

Thanks in advance if anyone can shed some light on this

Mon Oct 17, 2022 5:31 pm

Hello,

I would be interested to hear what FoxESS support come back with but all my installs are the same. I believe it's all to do with BMS calibration and how tricky LifePo4 batteries are to gain a true SoC. Whats likely happening is the missing capacity is either not being used and when it states 10% SoC it's really at 20% but the BMS is cutting off thinking it's a 10% or when you charge to 100% the BMS is registering 100% SoC too early and you're not technically fully charged. This issue is widely reported but there is no real solution.

I know foxess push out software updates regularly so hopefully this improves in time.

Interested to hear what FoxESS say.

Will

martindell · Tue Oct 18, 2022 10:13 am

That helps, thanks Will. Good to know it's not just me. I'll update here if / when I hear back from Fox

Tue Oct 18, 2022 10:39 am

Super thanks

Sccarbon · Thu Oct 20, 2022 8:10 am

I’m having the same issue, where my 4 batteries which I would assume need about 9Kw to fully charge, only use 7.3 Kw when fully discharged to fully charged.
Did you get a reply from FoxEss ?
Did you just email them through their website contact?

Thanks

Sccarbon · Fri Oct 21, 2022 6:50 am

After tracking the charge cycle for weeks and never seeing more than 7.3 Kw of charge, today they took 8.7Kw , which is close to the 9Kw I thought they should take (4 batteries).
Happy days, was thinking there was something wrong with the batteries or BMS.

Sun Oct 23, 2022 7:04 pm

Most welcome, thanks for the update

martindell · Thu Nov 10, 2022 11:45 am

Sccarbon wrote: ↑Thu Oct 20, 2022 8:10 am I’m having the same issue, where my 4 batteries which I would assume need about 9Kw to fully charge, only use 7.3 Kw when fully discharged to fully charged.
Did you get a reply from FoxEss ?
Did you just email them through their website contact?

Thanks

I didn't ever hear back from Fox :/. I just emailed service.uk@fox-ess.com. They did reply initially, did a firmware upgrade and then went silent - that was several months ago so I think the issue is 'closed' from their point of view