Prevent battery use in a given period

[if42]

Hi

How can I prevent the system from using the battery for a given period?

Eg I don't want to use the battery during an off peak period - I also don't want to charge the battery during this period.

Thanks!

[Dave Foster]

If you aren’t using any schedules the easiest way is to set a charge period for the period you don’t want the battery to discharge and make sure the ‘charge from grid’ switch is left off - it won’t charge from grid and won’t be used for discharge either.

If you do use schedules and have a workmode called ‘Backup’ use that to stop your battery from discharging, if you don’t have backup you will have to set a Force Discharge with an FDPower of 0 (zero)

[if42]

Hi Dave
Thanks very much for the reply.
I don't have a "backup mode", I'm using a KH10.5

Happy to use schedules, I tried this with just one schedule set:
17:00 - 23:59
Work mode: Force discharge
Min SoC: 15%
For discharge SoC: 100%
For discharge power: 1w
MaxSoC: 100

But didn't seem to do anything - the work model the time was "Feed-in Priority"
I did set it up and enable it after 17:00 not sure if that matters, as the time did not cross the start of the schedule.

I also tried a lower than current SoC for discharge SoC to see if it would work at all but that didn't seem to work either, it was using the battery anyway at the time but did not lower its use to 1w.

[Dave Foster]

Hi Dave
Thanks very much for the reply.
I don't have a "backup mode", I'm using a KH10.5

Happy to use schedules, I tried this with just one schedule set:
17:00 - 23:59
Work mode: Force discharge
Min SoC: 15%
For discharge SoC: 100%
For discharge power: 1w
MaxSoC: 100

But didn't seem to do anything - the work model the time was "Feed-in Priority"
I did set it up and enable it after 17:00 not sure if that matters, as the time did not cross the start of the schedule.

I also tried a lower than current SoC for discharge SoC to see if it would work at all but that didn't seem to work either, it was using the battery anyway at the time but did not lower its use to 1w.

With that force discharge set, the battery should have dropped to idle - it won't be 1 watt, it'll take the basic amount of power needed to keep the inverter and batteries from dropping into standby - usually around the 100 watt range. Also just to note the app is not real time and only takes samples every 5 minutes so it would take it a while before it reflected the changes.

[if42]

Thanks, will try again shortly and see what happens

[if42]

That didn't work still, but I have been playing around with the work modes, to see what actually does what and have managed to really confuse my inverter software

The inverter now considers power over 2kw as coming from the "load", which in my case at least is impossible.
I've emailed Foxess to see if they can sort this out.
If no reply I may try a inverter restart.

[Dave Foster]

It sounds like your Manager may have crashed, make sure all your schedules are clear and do an inverter restart (PV off, AC off, Battery off - wait until the screen goes blank and then battery on, AC on, PV on)

I’m suspecting you may have older firmware, so I would recommend you get updated to the latest.

[if42]

Thanks!
Restarted and all is well again.
Requested a firmware update, will wait on that and then try again.

[if42]

Firmware updated, I now have a backup work mode - will try that.

[if42]

On the latest firmware I have, which is:
Model: KH10.5 - Master: 1.43 - Slave: 1.01 - Manager: 1.42

Last night I had this work model, see screenshot. Min SOC 100% is the key component - I was wondering what it would do.
At midnight the battery started to charge from the grid at a rate of 1.25kw.

My question is, why 1.25kw?

Thanks!

[Dave Foster]

On the latest firmware I have, which is:
Model: KH10.5 - Master: 1.43 - Slave: 1.01 - Manager: 1.42

Last night I had this work model, see screenshot. Min SOC 100% is the key component - I was wondering what it would do.
At midnight the battery started to charge from the grid at a rate of 1.25kw.

My question is, why 1.25kw?

Thanks!

When you raise minSoC above the current SoC level the BMS requests a maintenance charge to bring the SoC up to the same level (i.e. not a full power charge), this is the same as would happen should SoC drop below 10%.

The maintenance charge is at approx 4A and is hard coded - it which would suggest your battery voltage was approx 312V at the time.

[alexls]

If you aren’t using any schedules the easiest way is to set a charge period for the period you don’t want the battery to discharge and make sure the ‘charge from grid’ switch is left off - it won’t charge from grid and won’t be used for discharge either.

I tried this yesterday, but the result was that all load was taken from the grid with the PV going to charge the battery. Not quite what I had in mind...

The idea is to use 'Self-use' or 'Feed-in priority' modes, but to have the excess load (i.e. load > PV) coming from the grid instead of the battery. This would be useful for when the import price drops below the export price (e.g. Agile import drops below the 15p fixed export) - for instance, it makes more sense to pay 12p to import rather than 'lose' 15p from the battery.
I haven't tried the Backup or FD methods - I may give that a go when circumstances next fit. But, wouldn't FD result in the battery not charging at all? And the description for Backup says it takes effect when the grid is off?

[Dave Foster]

I tried this yesterday, but the result was that all load was taken from the grid with the PV going to charge the battery. Not quite what I had in mind...

The idea is to use 'Self-use' or 'Feed-in priority' modes, but to have the excess load (i.e. load > PV) coming from the grid instead of the battery. This would be useful for when the import price drops below the export price (e.g. Agile import drops below the 15p fixed export) - for instance, it makes more sense to pay 12p to import rather than 'lose' 15p from the battery.
I haven't tried the Backup or FD methods - I may give that a go when circumstances next fit. But, wouldn't FD result in the battery not charging at all? And the description for Backup says it takes effect when the grid is off?

If you have Backup workmode always use that, it is designed to preserve battery soc and not allow it to fall (i.e. for when you might be expecting a power cut), the other methods are very inverter/firmware dependent - latest firmware being the best.

[alexls]

If you have Backup workmode always use that, it is designed to preserve battery soc and not allow it to fall

I can't schedule Backup mode. For instance, 12.30pm-2pm today the import price is 13.45p down to 10.5p. So I'd want to use grid instead of battery. From 2pm to 4pm it's under 10p so I may want to charge. And then after 4pm I want normal Self-use or Feed-in depending on what tomorrow's prices are. It's not practical to sit around manually changing the mode.

[alexls]

So the idea would be for the Self-use and Feed-in Priority modes to be modified; either additional modes, or with a modifier flag:

Self-Use (import)

• with PV Power
  Priority: load>battery>grid
  The energy produced by the PV system is used towards self-consumption with excess load being imported from the grid. Any excess energy is used to charge the batteries, then exported to gird.

• without PV Power
  When no PV is supplied, the load will be imported from the grid. Battery will charge when excess generation from other generation sources is detected.

Feed-in Priority (import)

• Priority: load>grid>battery
  In the case of the external generator, the power generated will be used towards supplying the local loads firstly, with excess load being imported from the grid or any excess generation exported to the public grid. The redundant power will charge the battery

[Will]

With Home Assistant, you can set the discharge amps to zero, which is what I do during the summer when I want no discharge or charging and everything to come from the grid. Obvs requires Modbus and a Home Assistant device to be always on.