FoxESS Community - Owners & Installers Forum

My system has been working fine since April thus year. Two nights ago it failed to charge and the battery was stagnant at 23% with the temperature at 2 deg C. That's odd I thought as the heating was enabled from 9deg to 15 deg overnight.
I reset the system and it started to warm up ever so slowly, but only through energy from the PV.
Last night I had the battery warmup function from 9 deg to 16 deg from 1600-2359 and then 0001-0659, commensurate with the charging as usual between 0001-0659 (Force charge max SOC 100% FD Power 3kW). The temperature started to drop by midnight and no battery warmup occurred.
I am on 1.006 firmware version. Th installer has stated that the system is fine and it is heating up but we have moved from 5.6 deg to 6.6 deg since 0845 this morning (now 1607). I have tried to charge the system as well - nothing is changing. Battery remains at 30% today.
I have read on FB that others are also having difficulty.
The installers have said that Foxess are working on a firmware update button one the app rather than FoxEss or the installer doing the update remotely. This appears a dodgy bit of software to first find issues on the first cold night of the year. Any one else have any wisdom?
Thanks
Bob

Inverter H1-3.7-E-G2
Battery 1.006 with slave on 1.06

Hi all,

For the second day running (cold temps in UK right now), I have the following issues with my heated EP11 battery:

- Not discharging in early morning (outside of overnight grid charging hours and before I start generating solar). So I'm drawing from the grid despite having an almost full battery that is well above the temperature it can discharge down to (5-8 degrees).
- Also, the heating function only seems to switch on when I'm generating solar or overnight grid charging and has never worked from its own battery power before (despite battery being well above the 55%(?) SOC needed to work?).

Sounds like others are in a similar position from the facebook forum and on here.

Does anybody know what Fox is doing about the heated function? I think I have reasonably recent firmware given my install was early summer. Thanks.

I thought I was sorted by resetting my mode scheduler, it worked (the battery charged again on schedule) for a day and now boom - nada again.

I was trying to get support from my installer but I have already flip flopped so many times (it's working/it's not working/it's working) that I give up and will eagerly await what others find. I will drop foxess support an email too and see if they say anything.

Sadly I haven’t any experience of the heater function but heard a lot of users that have had issues, generally updating the firmware has helped but I believe 1.007 onwards is good, albeit I can see the latest version is 1.009 onwards the Fox cloud.

Not sure whether you have seen the video created by Fox. I know others have found this useful https://fox-ess.tech/controlling-batte ... -fox-cloud

I know Will has posted these settings he normally uses

Thanks, the feature is simple to use and intuitive, but it's clearly not working properly. I'm on 1.007.

Craig in the video confirmed it should be able to use its own power to heat itself. Mine has never done this since I've had it and only heats when it is receiving solar. The battery is refusing to discharge despite it being almost full so my home is currently drawing from the grid. Really hope Fox take note of this and get a fix in place soon.

I will be watching the thread, and hopefully we get a solution to the problem.
I have one of the early ones, still on 1.005 for me.

I have the same issue as doubl0dave. I've got 2 EP11-H batteries on BMS F/W 1.007. The battery heating has worked during the last couple of daytimes as the ambient temperature fell (I'm using Will's recommendation to trigger on between 9C and 13C). However the heating did not trigger last night around 8pm when the lowest cell temperature fell below 9C (I can see this via Home Assistant modbus data). The batteries did force charge to 100% overnight, though now they won't discharge and I'm powered from the grid. The upside to the cold temperatures is minimal cloud cover, so I'm pulling over 2kW at 830am on my south facing roof. This is flowing to the EP11s and now they are warming. They're up to 12C now and I've set the Fox app to heat to 15C. Let's see if they discharge again once they're nearer 15C!

I have submitted a ticket, to see if the firmware can be updated. 1.005 to 1.008 from what I can see in Will's list of firmware versions.

Snap .. I am on 1.006 .. I have logged a ticket for them to review .... not sure if they will update firmware or not as part of the investigation

albie999 wrote: ↑Thu Nov 20, 2025 9:00 am Snap .. I am on 1.006 .. I have logged a ticket for them to review .... not sure if they will update firmware or not as part of the investigation

Good luck,

On a side note, in my phone app, I can set a range of temperatures from -40C to 50C for both ranges... that never seemed right to me, and in the picture above the temperature range isn't the same.

So the battery is heating now...

But why did it drop down to under 7oC before it started heating, when set to 9oC!?


https://ibb.co/BY6GH8V

Nope ... does not seem to be heating ... it is showing it is heating .. but the temperature is not increasing. I have switched off the heater, and now my battery is discharging like it should .. temperature is staying stable at 7.9c for now

Fox just confirmed that he grid time should be 0000-2359, but that does not explain why its warming up now then?

"Warmup slot in low price" is bit misleading!

Just received this back from Fox Support

My EP11s heating did kick in, so I've maxxed out the heating to 15c now! The heating range on my Fox app is shown on the attached picture which is the same as Craig's video:

https://fox-ess.tech/controlling-batter ... fox-cloud/

albie999 wrote: ↑Thu Nov 20, 2025 9:22 am Just received this back from Fox Support
fox-support.jpg

That will make overnight charging a challenge to heat and charge before your cheap hours run out.
If according to the app, it can use some of it's own power when above 55% SoC (IIRC) then that won't be too bad.

Well my BMS firmware was upgraded to 1.009 this morning. Initially the warm-up function was working with the battery going from 2 degrees up 11.6 degrees. It’s now climbing back down, currently at 9.4. Haven’t changed anything. The range I’ve set is 4-15 degrees. Is it worth me fully rebooting the ststem?

Ferryhill9 wrote: ↑Thu Nov 20, 2025 9:43 am Well my BMS firmware was upgraded to 1.009 this morning. Initially the warm-up function was working with the battery going from 2 degrees up 11.6 degrees. It’s now climbing back down, currently at 9.4. Haven’t changed anything. The range I’ve set is 4-15 degrees. Is it worth me fully rebooting the ststem?

A restart would eliminate a possible issue, so yes. Then you can move onto other possible things.

MaterialBarracuda48 wrote: ↑Thu Nov 20, 2025 9:36 am

albie999 wrote: ↑Thu Nov 20, 2025 9:22 am Just received this back from Fox Support
fox-support.jpg

That will make overnight charging a challenge to heat and charge before your cheap hours run out.
If according to the app, it can use some of it's own power when above 55% SoC (IIRC) then that won't be too bad.

Surely my battery would have warmed to 13oC at 0530, then been in use, so not dropped to as low as it has?

How are people rebooting their batteries to see if that makes any difference? My manual says I can do a battery shut-down and start up as per attached (hold power switch for 5 seconds etc and then start again with another 3 second power switch press)? Is anyone fully resetting their inverter as well? I've got a DC switch on the battery - I'm assuming I can leave that alone when doing the battery power switch reset? Any advice or insight is appreciated! TIA.

Thanks MB48 - Recycled the system, no change. Battery temp is still plummeting.

Not sure what to do next, when I approached my installer about the firmware update they pointed me to Fox. The problem as I see it is Fox has released a product that’s not fit for purpose. I’m sure many people are deciding where to have the battery/inverter installed at least partly based on the warm-up function feature, I know I did.

Ferryhill9 wrote: ↑Thu Nov 20, 2025 10:34 am Thanks MB48 - Recycled the system, no change. Battery temp is still plummeting.

Not sure what to do next, when I approached my installer about the firmware update they pointed me to Fox. The problem as I see it is Fox has released a product that’s not fit for purpose. I’m sure many people are deciding where to have the battery/inverter installed at least partly based on the warm-up function feature, I know I did.

Have you set the warmup slot grid time to 0000-2359?

oxfordmark wrote: ↑Thu Nov 20, 2025 10:45 am

Ferryhill9 wrote: ↑Thu Nov 20, 2025 10:34 am Thanks MB48 - Recycled the system, no change. Battery temp is still plummeting.

Not sure what to do next, when I approached my installer about the firmware update they pointed me to Fox. The problem as I see it is Fox has released a product that’s not fit for purpose. I’m sure many people are deciding where to have the battery/inverter installed at least partly based on the warm-up function feature, I know I did.

Have you set the warmup slot grid time to 0000-2359?

Yes, it was originally set to 00:01-23:59, I set it to 0000-2359 as suggested in the thread. No difference.

I am just totally confused now ..... so, based on the email from Fox that I posted ....... is it saying that basically ... I can either

1) "warm" up the bateries and not be able to charge or discharge (therefore pull from the grid)
or
2) can charge / discharge and power the house but the batteries gradually get colder and colder?

Example now .. that ... pulling from Solar and 100% charge ... but .. battery temp is dropping ... as I have turned off the heating module ... as if I turn it on ..... I then start pulling from grid .. even though I got battery

Ferryhill9 wrote: ↑Thu Nov 20, 2025 11:03 am Yes, it was originally set to 00:01-23:59, I set it to 0000-2359 as suggested in the thread. No difference.

Sorry to hear that it hasn't worked, I guess they are going to have to fix this out ASAP or a lot of people will be hopping mad.