FoxESS Community - Owners & Installers Forum

Hi All! I have just had my install completed and I am very happy with it for the most part. However I seem to have the issue where my battery is dumping power into my EV charger when IOG gives me smart charge slots. I have asked my electrician if he can re-wire it so that the inverter no longer sees the EV charger as a load as per the diagram attached. His response is below:

"We can certainly alter the system so that the EV charger is excluded from the battery monitoring, which would prevent the battery from discharging into the car when charging.

However, the battery system is designed to measure the whole-house current for an important reason: it allows the inverter to limit the maximum demand being imported from the grid. This is particularly beneficial where there are other large electrical loads in the property, such as an air source heat pump. If the EV charger is excluded from the monitoring, the inverter will no longer take that load into account, which may reduce its ability to manage the total import to the property effectively.

As an alternative, if you choose to charge the battery at the same time as the EV, this will prevent the battery from discharging into the car while still allowing the system to continue monitoring and controlling the overall maximum demand to the property."

I personally think I would prefer a hardware solution to the issue, especially since IOG gives slots randomly and I would have to manually change the inverter mode every time I get a slot.

Would appreciate thoughts from other people.

I don't know why this is so common with these EV installs, but sadly it is.


There are 2 main solutions as you may know, to split the power after it exits the meter, usually via a Henley block(s) and then placing the CT clamp for your inverter on a seperate 'branch' so the EV load becomes invisible. If space is tight for splitting the load, then you can wire up a CT clamp 'backwards' on the EV wire to your Inverter alongside the existing CT clamp, so that it takes the load off. example 14kW of load with EV now adds up to 7kW that the inverter then supplies.

Other way is via *software (and might be more beneficial) so that you charge the home battery at the same time as your car, which can give you a much needed boost in Winter specifically.

*You do need home automation, and a connection to the Inverter to control it, so might need additional hardware and certainly some configuration is needed.

If the EV charger has a setting to limit grid import then there is absolutely no issue with the setup shown in your diagram. If the EV and PV system are both charging the EV charger would be monitoring the total house load and if necessary would reduce the EV charge rate to keep it within the set limit.
Which inverter and EV charger do you have?

I'm going to add my solution to this thread too (because it costs next to nothing and works).
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