Hi All
I've have an H1-3.7-E with 3.7KW PV and 7.37KWh Mira-HV25 storage, installed a month ago. There is a wifi datalogger, i.e. cloud integration. I am generally very happy with the system.
I kept the Min SoC and Min SoC (On Grid) grid settings at default 10% and 20% respectively and then reduced the On Grid setting yesterday to 15%.
In both cases, the inverter allows the SoC to drop 4% below the On Grid setting before recharging from the grid starts, e.g. from 15% to 11%. Grid charge takes it SoC back to 14%, but I suspect 15% due to cloud monitoring.
Is this normal and am I risking long term battery performance dropping close to 10%, particularly in winter?
Many thanks
John
Falling below Min Soc on Grid
-
Dave Foster
- Posts: 1305
- Joined: Thu Oct 13, 2022 7:21 pm
If you don't have an EPS fitted (Emergency Power Supply) I would suggest you drop the Min SoC on Grid to 10% as well, your batteries are warrantied at 90% depth of discharge so you are better using it - in the depths of winter you might consider raising it back up to 15% to protect against the extreme cold should temps drop below 0C.
As for it dropping below min SoC, it's not usually a problem - in fact it's a sign of the BMS allowing the batteries to 'bottom' balance - dropping the Min Soc on Grid to 10% will also have a side benefit in that it will allow the BMS to learn the absolute packs limits and it will be better at predicting the pack SoC in future.
The BMS will gradually learn the pack limits, but unless you use the grid to charge to full, then discharge to 10% a few times - it can take the BMS and pack many weeks before the balance has resolved.
It's a wise idea to keep an eye on your firmware versions on both the inverter and the batteries - unfortunately Fox don't provide updates, but you'll find we often discuss new features in the groups - You can see your Inverter Firmware at the panel, by clicking on 'About, Inv Ver' - It will show Master, Manager & Slave - and for your batteries you click 'About, Bat Ver' where you will see Master, Slave.
If you post what they are now, someone will be able to check they are the latest (they have to updated remotely so usually an email to your installer, or to Fox support is all that is needed to update them).
As for it dropping below min SoC, it's not usually a problem - in fact it's a sign of the BMS allowing the batteries to 'bottom' balance - dropping the Min Soc on Grid to 10% will also have a side benefit in that it will allow the BMS to learn the absolute packs limits and it will be better at predicting the pack SoC in future.
The BMS will gradually learn the pack limits, but unless you use the grid to charge to full, then discharge to 10% a few times - it can take the BMS and pack many weeks before the balance has resolved.
It's a wise idea to keep an eye on your firmware versions on both the inverter and the batteries - unfortunately Fox don't provide updates, but you'll find we often discuss new features in the groups - You can see your Inverter Firmware at the panel, by clicking on 'About, Inv Ver' - It will show Master, Manager & Slave - and for your batteries you click 'About, Bat Ver' where you will see Master, Slave.
If you post what they are now, someone will be able to check they are the latest (they have to updated remotely so usually an email to your installer, or to Fox support is all that is needed to update them).
Thanks for the help and advice.
So, I've changed Minsoc on Grid to 10% and after a cloudy afternoon the SoC has just got down to 10% at 21:57 and the inverted switched to power from grid. I guess it will stay like this until the PV wakes up tomorrow (I don't have any charge from grid periods defined).
I'm happy that the SoC did not drop below 10% and will leave the config like this for now.
The firmware versions are as follows:
Inv Ver
Master 1.63
Slave 1.02
Com 1.70
Bat Ver
M 00.01.004
S1 01.00.01.01
S2 02.00.01.01
S3 03.00.01.01
So, I've changed Minsoc on Grid to 10% and after a cloudy afternoon the SoC has just got down to 10% at 21:57 and the inverted switched to power from grid. I guess it will stay like this until the PV wakes up tomorrow (I don't have any charge from grid periods defined).
I'm happy that the SoC did not drop below 10% and will leave the config like this for now.
The firmware versions are as follows:
Inv Ver
Master 1.63
Slave 1.02
Com 1.70
Bat Ver
M 00.01.004
S1 01.00.01.01
S2 02.00.01.01
S3 03.00.01.01
-
Dave Foster
- Posts: 1305
- Joined: Thu Oct 13, 2022 7:21 pm
Your inverter firmware versions are good - there has just been a minor update releases to Master 1.64 and Com(Manager) 1.71
Your battery firmware are older versions, so I would suggest getting them updated when you can as the later releases offer much better stability and temperature control - it's done remotely, so you can either ask your installer to do it, or raise a ticket with FoxESS and ask them to update your batteries to latest firmware.
An update for anyone who is also facing this.
With both MinSoc=10% and Min Soc on Grid=10%, the SoC continued to drop below MinSoC at about ~1% per hour, even with Load met from grid.
When SoC reached 8%, I baled and reset MinSoc on Grid to 15%.
Having watched this for a couple of days, I am convinced that the scenario is:
I am worried that at MinSoc on Grid, the SoC would drop to 5%. In the somewhat unlikely event that an extended grid outage occurred at that point, I am worried about possible damage.
As a PV newbie, I am very happy to be corrected and learn otherwise.
A screen shot from Home Assistant with FoxESS cloud integration and MinSoc on Grid = 15%:
With both MinSoc=10% and Min Soc on Grid=10%, the SoC continued to drop below MinSoC at about ~1% per hour, even with Load met from grid.
When SoC reached 8%, I baled and reset MinSoc on Grid to 15%.
Having watched this for a couple of days, I am convinced that the scenario is:
- 1.When PV=0, the SoC supplies Load with Soc gradually decreasing to the MinSoc on Grid setting, then
2. At SoC=MinSoc on Grid, the Inverter switches the Load to Grid, next
3. With the Load met by the Grid, the Inverter is still powered by the SoC, the Soc decreases gradually until it reaches MinSoc -5%, then
4. The Inverter starts a charge from grid until the SoC reaches MinSoc on Grid
5. Steps 1 to 4 repeat until PV comes on line and starts to pickup Load and charge the Soc
I am worried that at MinSoc on Grid, the SoC would drop to 5%. In the somewhat unlikely event that an extended grid outage occurred at that point, I am worried about possible damage.
As a PV newbie, I am very happy to be corrected and learn otherwise.
A screen shot from Home Assistant with FoxESS cloud integration and MinSoc on Grid = 15%:
- Attachments
-