Hello,
It seems that the API does not allow us to retrieve the temperature of EP11 batteries in the same way it is displayed in the application. The batTemperature endpoint appears to return an average temperature, whereas the application shows the minimum temperature of the cells.
How can we retrieve this minimum temperature via the API? Is the corresponding endpoint exposed?
Kind regards.
You’re correct it isn’t exposed, we’ve been asking for it ever since the OpenApi was developed and despite early indications that it would be added, more recently they have confirmed it won’t be.
That said, to their credit what Fox have done recently is to return the BMS charge / discharge current sensors, which are effectively the end results of cell temperature. You’ll find those returned in the get device real time data api call. The variables are ‘maxChargeCurrent’ and ‘maxDischargeCurrent’
That said, to their credit what Fox have done recently is to return the BMS charge / discharge current sensors, which are effectively the end results of cell temperature. You’ll find those returned in the get device real time data api call. The variables are ‘maxChargeCurrent’ and ‘maxDischargeCurrent’
Thank you for the response.
Indeed, do you mean that instead of monitoring the temperature directly, I only need to monitor the charge/discharge power to deduce whether the cells are too cold?
I hadn’t thought of that. What values are ideal? Is there a reference table for this?
Indeed, do you mean that instead of monitoring the temperature directly, I only need to monitor the charge/discharge power to deduce whether the cells are too cold?
I hadn’t thought of that. What values are ideal? Is there a reference table for this?
Here is an older video, and should give you some frame for reference.
ETA: Dave might have some better information, but the above could help.
ETA: Dave might have some better information, but the above could help.
OK, thank you very much. So this morning I recorded 17.7 °C in the application, and the API returned "maxChargeCurrent": 13.0. That seems to correspond to the table.
I’m thinking of activating my heating pad when "maxChargeCurrent" < 10, and turning it off when "maxChargeCurrent" > 22, knowing that it will be unplugged during the summer.
I’m thinking of activating my heating pad when "maxChargeCurrent" < 10, and turning it off when "maxChargeCurrent" > 22, knowing that it will be unplugged during the summer.
The charge / discharge curves vary across inverter models and firmware, but not by a lot - best thing to do is a bit of observation on your system (note the battery temperature returned by the API is BMS temp which is often 6-10C higher than lowest cell)
That sounds like a planGarz69 wrote: ↑Tue Mar 10, 2026 8:24 am OK, thank you very much. So this morning I recorded 17.7 °C in the application, and the API returned "maxChargeCurrent": 13.0. That seems to correspond to the table.
I’m thinking of activating my heating pad when "maxChargeCurrent" < 10, and turning it off when "maxChargeCurrent" > 22, knowing that it will be unplugged during the summer.
Thanks to both of you for your help — much appreciated! 
I have some temperature values here you can check your results against.
viewtopic.php?p=13378#p13378
The values being returned by the API are the BMS max charge and discharge current. These are different to the inverter max charge and discharge currents. There is also the max charge and discharge power of the inverter that you may need to take into account.
What you may need to look at is the impact of the current limitations imposed by the BMS, relative to your desired charge and discharge power and time window.
For example, suppose you have 1 x EP11 with a nominal voltage of 384v and a 7kW inverter. The max charge power you can get from the inverter is 7kW AC, 6.8kW DC, giving a 'normal' charge current of 17.7A at 384v. So, even if the BMS max charge current shows 25A or 50A, you will only charge at 17.7A.
The temperature only impacts charging when the BMS max charge current is less than this. So, at 13A, the charge power will be around 5kW. At this current, the battery will take around 2 hours to charge fully from 10% to 100%.
So, look at the values you are getting and check what current you need to maintain to achieve your desired charge time.
In my case, the max charge current varies between 15A and 25A over the temperature range I see. I set the inverter max charge current to 15A as this always gives me a consistent and predictable charge time.
Using the API, you can also get the history of the maxChargeCurrent, along with your SoC and batTemperature (cell temp is approx 10C lower than this). Here's an example of doing this for my inverter:
What you may need to look at is the impact of the current limitations imposed by the BMS, relative to your desired charge and discharge power and time window.
For example, suppose you have 1 x EP11 with a nominal voltage of 384v and a 7kW inverter. The max charge power you can get from the inverter is 7kW AC, 6.8kW DC, giving a 'normal' charge current of 17.7A at 384v. So, even if the BMS max charge current shows 25A or 50A, you will only charge at 17.7A.
The temperature only impacts charging when the BMS max charge current is less than this. So, at 13A, the charge power will be around 5kW. At this current, the battery will take around 2 hours to charge fully from 10% to 100%.
So, look at the values you are getting and check what current you need to maintain to achieve your desired charge time.
In my case, the max charge current varies between 15A and 25A over the temperature range I see. I set the inverter max charge current to 15A as this always gives me a consistent and predictable charge time.
Using the API, you can also get the history of the maxChargeCurrent, along with your SoC and batTemperature (cell temp is approx 10C lower than this). Here's an example of doing this for my inverter:
H1-6.0-E hybrid inverter
6 x HV2600 v2 batteries
16 x JA Solar 405w panels
7 x Tigo TS4-A-O optimisers
6 x HV2600 v2 batteries
16 x JA Solar 405w panels
7 x Tigo TS4-A-O optimisers
Thank you for this clarification. In my case, it’s mainly about protecting the battery from the cold (unfortunately I have a model without built-in heating). I’m not really trying to optimize charging that much; in winter, the house uses almost all the production anyway, and I’ve noticed that the cells warm up quite quickly when the sun comes out.
That said, I haven’t really looked into the potential benefit of keeping "maxChargeCurrent" at 15 A. I’ll look into that next winter (temperatures have now gone back up where we live).
That said, I haven’t really looked into the potential benefit of keeping "maxChargeCurrent" at 15 A. I’ll look into that next winter (temperatures have now gone back up where we live).