Battery Discharging into Car Charger

[rexxcalibur]

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.

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[MaterialBarracuda48]

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.

[nrb501]

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?

[Grumps]

I'm going to add my solution to this thread too (because it costs next to nothing and works).
download/file.php?id=3143&mode=view
viewtopic.php?t=2886&start=25

[Devonlad]

Hi all,
Thanks so much for all your inputs, much appreciated and very impressed, being totally new to this forum. There's lots to think about and mull over, as I'm just wanting a simple solution.
In the interim I think I'll just temporarily cancel out of IOGs Smart charging until my EV has overnight charged and then restart the Smart charge again when car's reached it's set charge limit - not ideal, but workable I suppose. I do only charge once or twice a week.
My old system, just taken out,was Givenergy and I never had this problem. The Zappi was set to export about 100 watts when installer set it up, but doesn't seem to affect the Fox system.

[MaterialBarracuda48]

With Home Assistant running and connected to your Inverter, then you can force the system to charge the battery when you get a cheap IOG slot, as mentioned in the thread, it helps in Winter to keep battery topped up as you tend to use more around the home.

The other method is, just stop the draining by 'blinding' the charger from the Inverter, so it stops feeding it. Both have costs in setting up, so you have to make a choice on what's the most simple/cheapest way to achieve your aim.

Best of luck.

[Devonlad]

Hi Everyone and many thanks for your input.
I'll talk to my installer tomorrow and see what he has to say. I think rewiring might be a challenge as the Zappi, inverter and batteries are all in the garage 30 meters away from the consumer unit.
I am tempted to try changing the Self-use setting to Backup in the app, but will wait to speak to installer. I will look at Home Assist, but as I'm not that good with computers etc. I think it will defeat me, but will look at Youtube to see what it's like.
It's a shame that Fox and Octopus haven't got this sorted yet for IOG and the Smart Tariff segments - as Givenergy had before.