Hi All, Just had a 14kW array installed KH10 inverter and EP12 battery. It was turned on at 14:30 on Monday the 9th so we've not had a lot of sun to test under yet. Two behaviours I'm a bit unsure of.
First, the battery is set to minimum SOC of 10%, when it gets to 10% it charges up to 15% off the grid and then discharges down to 10% and repeat in cycles.
Second, When we do have brief gaps in the cloud and get generation the amount generated from solar, discharged from batter and imported from grid is often higher than usage For instance it currently reads
Solar 323W, Battery 169W Discharging, Grid 7W importing. Home 247W usage. Which seems to be 252W too much power usage. This is true at several points.
Whilst the weather is poor it’s better to put some grid charge into the battery, particularly if you have access to a low overnight tariff - the inverter essentially runs off battery when there is little solar, and whilst it doesn’t consume a lot of power it is responsible for the cycling you are seeing when the battery reaches minsoc.
The information you are looking at is not real time and as loads are dynamic it only really gives a guide as to what the system is doing, your energy statistics (power over time) tell you the real story. But I think the difference you are looking at are system losses, without much sun the system is running at it’s most in-efficient and there will be conversion losses from solar and battery from DC to AC, plus losses in the battery through battery chemistry particularly whilst it’s cylcing like that - the losses become relatively insignificant when you have lots of sun or high loads.
Assuming you are in the UK, February has been dismal so far, over 50% solar less compared to last year, but the days are starting to get longer and the suns elevation is increasing so it won’t be long now (the solar forecast for Saturday is looking good).
The information you are looking at is not real time and as loads are dynamic it only really gives a guide as to what the system is doing, your energy statistics (power over time) tell you the real story. But I think the difference you are looking at are system losses, without much sun the system is running at it’s most in-efficient and there will be conversion losses from solar and battery from DC to AC, plus losses in the battery through battery chemistry particularly whilst it’s cylcing like that - the losses become relatively insignificant when you have lots of sun or high loads.
Assuming you are in the UK, February has been dismal so far, over 50% solar less compared to last year, but the days are starting to get longer and the suns elevation is increasing so it won’t be long now (the solar forecast for Saturday is looking good).
Congrats!datamonkey wrote: ↑Wed Feb 11, 2026 10:37 am Hi All, Just had a 14kW array installed KH10 inverter and EP12 battery. It was turned on at 14:30 on Monday the 9th so we've not had a lot of sun to test under yet. Two behaviours I'm a bit unsure of.
And I would say you are UK resident, so I am thinking you will love this coming Saturday.
You BMS inside your battery is probably still in dire need of calibration with your EP12 being so new, so it might be doing a charge to protect the low cell Voltages. It can also do this if the battery pack is cold to protect itself, but not likely at the moment.datamonkey wrote: ↑Wed Feb 11, 2026 10:37 am First, the battery is set to minimum SOC of 10%, when it gets to 10% it charges up to 15% off the grid and then discharges down to 10% and repeat in cycles.
I used to have this behaviour with the older FW versions (at least this is what I attribute this to, as I had same "issue" of missing power) not tallying up to zero.datamonkey wrote: ↑Wed Feb 11, 2026 10:37 am Second, When we do have brief gaps in the cloud and get generation the amount generated from solar, discharged from batter and imported from grid is often higher than usage For instance it currently reads
Solar 323W, Battery 169W Discharging, Grid 7W importing. Home 247W usage. Which seems to be 252W too much power usage. This is true at several points.
Your FW versions might need updating for several components, I have attached a video here that shows you some solar activity, and you will see that everything tallies up to zero. You might also observe that I have 5 second refresh as you can see in top right countdown, quick way to know if you are up to date or not.
You can check your firmware versions for all your component in the App, by pressing Device at the bottom of your screen, and when you press on an item, you will see a Serial Number you can click on, pressing this reveals current loaded FW
Yes, I'm in the UK and cannot wait till Saturday. Even with today's cloud cover I'm getting periods of charging the battery from solar which is nice. Saturday is going to be huge.
We don't currently have a low overnight tariff, waiting for British Gas to give us an MPAN for our SEG and then looking at whether switching to Ocopus Flux or intelligent flux.
My app is definitely on an older version because I'm only getting the 3-5 minute updates rather than 5 second updates. But even so looking at the data It would be more right if only 25% of the solar was getting through.Hopefully it is just reporting lag because looking at losses when I'm generating 498W DC I'm pushing 453W AC. Which seems right to me.
I'll give the battery a week or so to stabilise and then I might lift the SOC floor to 15%.
We don't currently have a low overnight tariff, waiting for British Gas to give us an MPAN for our SEG and then looking at whether switching to Ocopus Flux or intelligent flux.
My app is definitely on an older version because I'm only getting the 3-5 minute updates rather than 5 second updates. But even so looking at the data It would be more right if only 25% of the solar was getting through.Hopefully it is just reporting lag because looking at losses when I'm generating 498W DC I'm pushing 453W AC. Which seems right to me.
I'll give the battery a week or so to stabilise and then I might lift the SOC floor to 15%.
Roll on Saturday for sure.
I am on Octopus Intelligent Go as have EV and compatible charger... you ***might*** be able to join Octopus Go as it was just a simple tick a box to say you have an EV, though they may have changed rules recently as they are clamping down.
Check App version, pressing Me on bottom right will show you.
Here is a list of the minimum software levels for App/Inverter and Datalogger https://fox-ess.tech/5-second-live-ener ... d-devices/
If you are behind, and odds are you will be, then send email to service.uk@fox-ess.com and give the Serial number for the items you want updating, or you can ask your installer, some are good at helping... others can be lagging.
You could raise the min SoC to 15%, but you are removing capacity off your plate.. if you do decide to increase values, make sure to once a month discharge down to 10% and back to 100% as this calibrates the end points and increases the reported SoC more accurately.
I am on Octopus Intelligent Go as have EV and compatible charger... you ***might*** be able to join Octopus Go as it was just a simple tick a box to say you have an EV, though they may have changed rules recently as they are clamping down.
Check App version, pressing Me on bottom right will show you.
Here is a list of the minimum software levels for App/Inverter and Datalogger https://fox-ess.tech/5-second-live-ener ... d-devices/
If you are behind, and odds are you will be, then send email to service.uk@fox-ess.com and give the Serial number for the items you want updating, or you can ask your installer, some are good at helping... others can be lagging.
You could raise the min SoC to 15%, but you are removing capacity off your plate.. if you do decide to increase values, make sure to once a month discharge down to 10% and back to 100% as this calibrates the end points and increases the reported SoC more accurately.
OK, got the inverter management software updated and get 5 second updates. That seems to have solved the discrepancy in the Loads going in and out. Since the updatd they've been within 10W either way.
Then I used the grid to charge the battery to 100% (around 15:15 - 17:35 on the 11th) and when it next hit 10% (22:45 on the 12th) it stayed there. Until 3:15 in the morning when it randomly used the grid to charge to 30%.
Slightly confused as to what caused that. Charge from grid is off. The battery sat at 10% for exactly 4.5 hours and then boom, charged at 1.5kW for about an hour to 29%
Then I used the grid to charge the battery to 100% (around 15:15 - 17:35 on the 11th) and when it next hit 10% (22:45 on the 12th) it stayed there. Until 3:15 in the morning when it randomly used the grid to charge to 30%.
Slightly confused as to what caused that. Charge from grid is off. The battery sat at 10% for exactly 4.5 hours and then boom, charged at 1.5kW for about an hour to 29%
That is most likely the BMS in the battery in protection mode, Dave will confirm if this is the case.
From what I know, it does this if the temperature is low, or if the cell Voltages are low.
From what I know, it does this if the temperature is low, or if the cell Voltages are low.
1.5kWh is what you would expect when the BMS requests a maintenance charge, so that looks like the BMS taking control to either balance your cells (possible as it's a new install) or more likely the temperature was low whilst your minsoc was at 10% - can you see what your lowest cell temp was at that time.
I don't know where I would see historic cell temp data. It was down between 0°C and 1°C last night which is where I have the heater set to turn on. But yeah, makes sense for it to be temp protection. I'll stop panicking every time it does something soon, I'm sure.
Login here with you credentials: https://www.foxesscloud.com/v2/logindatamonkey wrote: ↑Fri Feb 13, 2026 12:14 pm I don't know where I would see historic cell temp data. It was down between 0°C and 1°C last night which is where I have the heater set to turn on. But yeah, makes sense for it to be temp protection. I'll stop panicking every time it does something soon, I'm sure.
Devices
Battery, and open it.
I was just wondering if Will had made a video on this subject... turns out he has 
Channel link for his other videos, leaving this here so others can find
https://www.youtube.com/@iameccles/videos
Channel link for his other videos, leaving this here so others can find
https://www.youtube.com/@iameccles/videos
I don't seem to have the Filter buttons on any of the battery graphs. But I found it on the Inverter Graph.
Min Cell Temp was 3C and that's the first time it's got that low. It charged until min Cell temp was 5C. So Temp protection seems likely
Min Cell Temp was 3C and that's the first time it's got that low. It charged until min Cell temp was 5C. So Temp protection seems likely
It can come and go as Fox decidedatamonkey wrote: ↑Fri Feb 13, 2026 1:10 pm I don't seem to have the Filter buttons on any of the battery graphs. But I found it on the Inverter Graph.
Min Cell Temp was 3C and that's the first time it's got that low. It charged until min Cell temp was 5C. So Temp protection seems likely
I have a screenshot from the other day where Filter button is missing, and today it is there 
Anyhow, seems you have the answer, the battery was cold. So best guess it must be installed on outside wall.
Check this monster battery thread for some solutions, mine is in garage so I went low tech and free
viewtopic.php?p=12260#p12260
albie999 has gone with the posh approach
viewtopic.php?p=12714#p12714
I have seen pictures of external installs, but cannot find post currently. But some kingspan and wooden frame around, or even just a wooden frame with not too much ventilation would do it, just make sure to remove in Spring and put back in Winter only.
EDIT: found it
CDubbs post
viewtopic.php?p=12645#p12645
What FW version is your EP12 running out of the box?
If it is very old, then the heating controls are just for show only, it doesn't work. Some of the newer versions are still with bugs that stop charge/discharge. The linked EP11 thread applies to your EP12, so you are sure to have read some of the fun goings on in there by now.
If it is very old, then the heating controls are just for show only, it doesn't work. Some of the newer versions are still with bugs that stop charge/discharge. The linked EP11 thread applies to your EP12, so you are sure to have read some of the fun goings on in there by now.
Yeah, It's on an outside wall and gets a fair amount of breeze
I might look at building some sort of insulation box for next winter. The battery is on version 1.011
I might look at building some sort of insulation box for next winter. The battery is on version 1.011
Last edited by datamonkey on Fri Feb 13, 2026 3:03 pm, edited 1 time in total.
Fox implied to me that this behaviour is in fact *not* normal, and seems to have been fixed in more recent inverter firmware.First, the battery is set to minimum SOC of 10%, when it gets to 10% it charges up to 15% off the grid and then discharges down to 10% and repeat in cycles.
I had a protracted discussion with Fox support on this matter and finally got a "beta" firmware (0.59) installed that stopped the behaviour on my KH7. It now sits at MinSoC normally (10%) when there is no solar/grid charging.
The main annoyance for me was that the charging (from 10 to 15) side of these cycles is totally unaccounted in many places, so my Home Assistant setup seemed to show my system magically generating energy from nowhere.
I think you should be ok on v1.011, well mostly as it's still a messy situation. Have you seen it heat up when you enable it, normally you would see an animation.
Next Winter might be a good idea to have something in place, my blanket has kept mine toasty enough to not need heating since I put it on.
Next Winter might be a good idea to have something in place, my blanket has kept mine toasty enough to not need heating since I put it on.
I've not seen it heat up but I've only just realised I had the "Turn heat on" set to 0C so it's not been cold enough. Next time the temp drops I might raise the heat up temp just to see if the function works.
Been having an interesting time with the 71 variables available under filters trying to understand what they all mean.
With no Data:
My PowerFactor is exclusively 1 or 0, I was expecting to see 0.9s in there so I don't know if that's monitoring issue or just low expectations.
ambientTemperation is clearly not outside temperature, I presume it's air inside the inverter or something.
batTemperature seems signifcantly higher than cellTemperatureHigh and Low (12.4 compared with 5.5 and 2.9). I presume the heating is based on batTemperature. rather than Cell Temp.
Been having an interesting time with the 71 variables available under filters trying to understand what they all mean.
With no Data:
- pv5 and pv6 are null because I only have 4 lines of panels.
- meterPower2 is null, I only have one meter.
- Everything on S and T is null but I have stuff on R. I don't know what those letters mean.
- epsPower, epsPowerR are null. I don't have an emergency power system so that makes sense but epsVoltR (220-240V) and epsCurrentR (0.8 - 1.0) exist so that seems odd know why epsPowerR is null.
- loadsPowerR and meterPowerR are also null
- boostTemperation, chargeTemperature and dspTemperature
My PowerFactor is exclusively 1 or 0, I was expecting to see 0.9s in there so I don't know if that's monitoring issue or just low expectations.
ambientTemperation is clearly not outside temperature, I presume it's air inside the inverter or something.
batTemperature seems signifcantly higher than cellTemperatureHigh and Low (12.4 compared with 5.5 and 2.9). I presume the heating is based on batTemperature. rather than Cell Temp.
You actually need to raise the min temp. as this is what makes it start to heat. Mine is set to begin warming at 9°C and stop heating at 15°C. Video you can see here with range and animation video viewtopic.php?p=10871#p10871datamonkey wrote: ↑Fri Feb 13, 2026 8:36 pm I've not seen it heat up but I've only just realised I had the "Turn heat on" set to 0C so it's not been cold enough. Next time the temp drops I might raise the heat up temp just to see if the function works.
ambientTemperation: I think is your Inverter temp.datamonkey wrote: ↑Fri Feb 13, 2026 8:36 pm ambientTemperation is clearly not outside temperature, I presume it's air inside the inverter or something.
batTemperature seems signifcantly higher than cellTemperatureHigh and Low (12.4 compared with 5.5 and 2.9). I presume the heating is based on batTemperature. rather than Cell Temp.
batTemperature: The BMS inside your battery pack, brain basically
Heating works on you lowest cell Temp, so 2.9°C in your case