Inverter (Kodak OG6.2) displays some odd behaviour:

2 examples:

1) Boiling a kettle (top is load and bottom is battery draw in watts at same time)

• Why would it be pulling 419w out of the battery when there should be sufficient PV and grid?

2) Idle household usage (top is load and bottom is battery draw in watts at same time)

• Almost no grid being used, enough PV to cover load, but battery being discharged by 250-ish watts
• 
• 

Edited June 26, 20233 yr by Acheron

Was your battery fully charged at that time?

3 hours ago, Jacques Ester said:

Was your battery fully charged at that time?

Yep.

8 hours ago, Acheron said:

11 hours ago, Jacques Ester said:

Was your battery fully charged at that time?

Yep.

In that case, depending on settings or the BMS behaviour, the battery will discharge a little to settle on the float voltage. For my home-made LFP system, this takes the battery State of Charge from 100% to about 99.5%. At that point, the current into and out of the battery bounces about a little, averaging very close to zero, keeping the battery at 99.5% SoC. This allows for maximum battery longevity, staying away from the highest battery voltage that is necessary to fully charge the battery.

So as long as it doesn't keep discharging the battery, I'd say that this is normal. I've heard of some battery BMSs operating from 100% down to 95% SoC and back again, which seems to be roughly the same thing.

6 hours ago, Coulomb said:

In that case, depending on settings or the BMS behaviour, the battery will discharge a little to settle on the float voltage. For my home-made LFP system, this takes the battery State of Charge from 100% to about 99.5%. At that point, the current into and out of the battery bounces about a little, averaging very close to zero, keeping the battery at 99.5% SoC. This allows for maximum battery longevity, staying away from the highest battery voltage that is necessary to fully charge the battery.

So as long as it doesn't keep discharging the battery, I'd say that this is normal. I've heard of some battery BMSs operating from 100% down to 95% SoC and back again, which seems to be roughly the same thing.

Unfortunately it does seem to keep discharging (at differing amounts) throughout the day until the next charge cycle occurs.

I had this behaviour before I added solar, but it was limited to a semi constant 20-40w discharge.

Now that I've added solar this seems to fluctuate wildly, almost as if the battery needs to compensate?

 

Last hour: (PV is low due to rainy weather+time)

 

Yesterday (also rainy, but just showing the trend with valleys of discharge power over the day). Inverter is running on SUB and there was no loss of grid so cannot fathom why it needs to use any battery here.

 

Night time hours with no PV (note the constant, but lower battery discharge)

 

Edited June 27, 20233 yr by Acheron