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Bizarre behaviour from the battery (discharging... but charge percentage going up?)

Posted: Sun Feb 18, 2024 8:40 pm
by r00x
Anyone else encountered this? Just spent the last couple hours watching my battery charge allegedly creep *upwards* to 98%, all while discharging and running the house. The fox cloud, HA, and my electricity meter all agree on the battery & inverter being the power source.

As for the charge level, it reached 98% and reached a plateau. Fox cloud reports it's "working", not charging, but it still shows 98%.

It threw an error earlier in the day (over-voltage error according to cloud... "bat volt fault" according to inverter display, followed by "Bms HW Protect" and ""Bat Volt Low"...) - right at the moment this happened, the Battery Current sensor in Home Assistant went mental and has been giving stupid readings ever since (i.e. +40A or more charge current.. while discharging) and even the fox cloud shows weird readings (at time of writing... 29.9A, ostensibly charge... while saying it's discharging).

Meanwhile, on both systems, the *inverter* battery current seems sensible and shows values corresponding with what the battery is actually doing. Only the "battery current" figure is bonkers. As far as I can tell they're supposed to be opposite? I.e. if one is -9A, the other should be 9A... that's how it usually is in Home Assistant, at least.

There are no spurious voltage readings in HA at the time of the error - all looks very normal (~120V, for a 5.8kWh battery).

Things that seem to work (giving correct values. and have been all along) on both HA and Foxcloud:
- BMS kWh remaining
- Battery Voltage
- Inverter Battery Current
- Battery Charge
- Battery Discharge
- Inverter Battery Power

Things that seem completely broken on both HA and Foxcloud:
- Battery Current
- Battery SoC

Inverter: H1-5.0-E
Batteries: CM2900 & CS2900

Re: Bizarre behaviour from the battery (discharging... but charge percentage going up?)

Posted: Sun Feb 18, 2024 9:54 pm
by Dave Foster
The inverter battery current is the most reliable and a true indication of what is happening, but it sounds like your BMS has lost the plot following the alarm it raised -that usually causes it to open it’s contactor and stop feeding the inverter but in this case it sounds like that hasn’t happened.

I would strongly recommend powering off the batteries, you’ll need to take down the whole system to do that - starts with PV isolator open, AC isolator open, battery power off, battery isolator open - wait 30 seconds and reverse that.

What batteries are they ?, do they have latest firmware ?