FoxESS Community - Owners & Installers Forum

Hi,
Just installed a BMS and 2 x Mira 25 batteries. When powering on they are charging off the grid. It’s dark outside and I’ve disabled charge from grid on the FoxCloud app. Any help very much appreciated!

H1-3.7-E
Mira BMS
2 x Mira HV25’s

If you have disabled grid charge in the app and work mode is set to self-use they should stop charging.

They will then only charge off grid if they are extremely cold (< 0C unlikely), or their SoC (state of charge) is below the set minsoc and minsoc on grid settings - these are normally set around 10-20% but if the batteries are below that they will charge from grid until they exceed that level - check you minsoc settings.

What Inverter do you have, does it recognise the bms/batteries are fitted - if you look at the panel and select About, Bat Ver - does it display the Master (M:xxxxxxx = BMS), and 2 * Slaves (S:xxxxxx = batteries)

It’s a H1 3.7-e inverter. Installed inside so not a low temp issue. Work mode set to self use. Min SoC is set to 20% for on/off grid. Can see m: #### s1: #### s2: #### in the battery ver about info.

Just checked the setting on the app coincide with the actual inverter and they do.

If the battery soc is above 20% then they shouldn't charge (below that they will to get to 20% irrespective of what your settings are)

Has the install been in for some time ?, if the CT clamp has been installed the wrong way round, or in the wrong place one of the behaviours is that the batteries charge from grid, then discharge back to the grid repeatedly.

Can you post a screen shot of the real time data screen from your app - you should see power flowing towards the house from either the PV or batteries (not the other way round)

It’s a new install, I’ve had issues with the realtime data showing the power flow going from my house but sometimes it’s ok. At the moment we aren’t using almost 7kw. I did try previously to switch the ct clamp around and that made the realtime data look even worse.

Just checked the CT clamp and I think its incorrect. See pictures of before and after for where I think it should be. Please correct me if I'm wrong! The real time data looks good now.

Ok, yes looking at the data screens the CT clamp was definitely the wrong way round before.

The CT clamp position was ok but I suspect the polarity of the cable has been crossed by the installer - normally the arrow should point towards the grid (which it did), but in the new position the arrow is pointing towards the house which tells me the cable has been reversed - it would have worked where it was with the arrow pointing towards the house - but it doesn't make a huge difference being on the input or output of the meter.


Just a quick note the real-time data screen is a snap shot taken every 5 minutes so not very 'real' time, you have to give it some time to take a number of readings before you can rely on it.

Hopefully this will work ok, the only observation I would make is the live feed from the meter goes into the black Henley block where it splits, that is normally what happens when you have an EV charger fitted (or a split consumer meter).
If you do have an EV charger fitted, where the CT clamp is fitted now the inverter will see the EV charger as house load and try and supply it from the batteries which will flatten them real quick - if you do have an EV charger, find out which one of those live feeds that comes out of the block is going to the house and which is going to the charger - put the CT clamp on the one going to the house and point the arrow towards the house.

I don’t have an EV charger so shouldn’t be an issue. There was no room on the existing consumer unit so another was installed when we had the new equipment fitted.

Thanks for your help, hopefully that’s it sorted!

Plumbstone wrote: ↑Wed Oct 04, 2023 3:13 pm Thanks for your help, hopefully that’s it sorted!

Your welcome, glad it's sorted

Further to this, got system sorted for not charging off the grid but now I’ve got the problem of it inverter still drawing power from the grid when there is plenty of battery. I thought the self use work mode should use the battery first.

Yes it should, as long as the batteries SoC was above minsoc (what was your SoC at when the screen shot was taken?)

And the second thing to check is that you don't have a time period set in the battery charge - if you have anything other than 00:00-00:00 (even with the switch off) it will not use the battery to meet the load during that period, other than the small amount of power it needs to run the inverter ~100w.

Yep, it was the timing. All sorted!!