FoxESS Community - Owners & Installers Forum

Hi all,

I've just had an additional HV25 installed, giving a total of 3 batteries and 7.35kw theoretical maximum capacity.

I'm looking at my system on the web and I can't seem to find and easy to understand figure for my new capacity or number of batteries installed.

I just want to make sure the BMS is 'seeing' and using the extra storage.

Any help would be greatly appreciated.

Thanks, G

The only really good way to do this is to run the SOC down to minimum and then charge it up to max, and see how much juice goes into it. While you're doing that it's a good opportunity to balance the modules:

The belt and braces attempt to correct balance is to allow the batteries to discharge to 10% and leave them like that for at least a couple of hours (the charger will cycle occasionally to maintain).
The next step is to charge your batteries from grid to 80% then reduce your max charge current to 4A and grid charge to 100%, and leave it with charging on for a couple of hours after it reaches 100%.

it will take some time to do this manually, it is actually easier just to set the low charge (4A) and leave it like that for the whole night - the most important thing is giving it time to float charge when it is at 10% and 100% - this gives the batteries time to absorb charge, and for the shunts to dissipate excess cell volts all of which helps with balance.

Hi Calum, thanks for taking the time to reply, much appreciated.

I'll try running the SOC down to 10% (my minimums are set to 20% at the moment, the installer said anything below 20% was not great for the batteries until the hours of sunshine significantly increase) and then monitoring how much charge goes in.

I've attached a screen shot of the charge per hour (the sun has been out pretty much since 0800 and the batteries got to 100% charge at around 1230). The columns only add up to 4.7KWh, when the theoretical maximum of 3 x HV25 is 7.35KWh, so I'm pretty certain the new battery isn't being charged. I know that I can only use 80% of the total capacity (or 90% if I reduce the Min SOC to 10%) but surely I should be storing somewhere around 6.9ish KWh on a very sunny day, as today has been. And, as I say, the batteries stopped charging at around 1230 and I started sending back to EDF.

I think balancing the modules is way out of my capability at this point until I dive in a bit more.

Any thoughts would be much appreciated.

Kind regards.

I think you have to insert the screenshot into the post for me to see it!

Balancing the batteries basically boils down to discharging the pack down as low as you can, leaving it there for a couple of hours, and then charging it all the way back to full, slowly, and leaving it there for a couple of hours.

The "charging slowly" part is achieved by temporarily reducing the maximum charging current in the Inverter menu to the minimum value.

calum wrote: ↑Thu May 11, 2023 4:56 pm I think you have to insert the screenshot into the post for me to see it!

Balancing the batteries basically boils down to discharging the pack down as low as you can, leaving it there for a couple of hours, and then charging it all the way back to full, slowly, and leaving it there for a couple of hours.

The "charging slowly" part is achieved by temporarily reducing the maximum charging current in the Inverter menu to the minimum value.

Right, let's try again!

What was the SoC of the battery when you started charging it today? Worth noting that 80% of 7.5 is 6, assuming your minimum SoC is still set to 20%...

Given that all the battery modules won't have been balanced on install, the BMS would most likely reduce its assessment of how much charge can go in, which could explain at least part of the difference you're seeing. Also worth noting that the batteries achieve their rated capacity at 25C, I'm guessing if you're in the UK it'll be a bit cooler than that.

Lastly do you know what firmware versions you're running? You can see this on the front panel of the inverter in one of the menus (sorry I can't recall where off the top of my head). If you're running an older firmware this can mean that you don't get the full capacity because the SoC tracking is off.

I'd ask your installer to ensure the latest firmware is installed, and also try the battery balancing procedure outlined above...

So have had a read of the H1-3.7-E user manual.

To get to reduce max charge current it's MENU> SETTING> BATTERY> MAX CHG CUR, think this is correct?

According to the manual, max current is 40A, doesn't give a minimum so I assume there will be a figure I can't go below in the settings? Do you happen to know what that number is?

Thanks again!

calum wrote: ↑Thu May 11, 2023 5:21 pm What was the SoC of the battery when you started charging it today? Worth noting that 80% of 7.5 is 6, assuming your minimum SoC is still set to 20%...

Given that all the battery modules won't have been balanced on install, the BMS would most likely reduce its assessment of how much charge can go in, which could explain at least part of the difference you're seeing. Also worth noting that the batteries achieve their rated capacity at 25C, I'm guessing if you're in the UK it'll be a bit cooler than that.

Lastly do you know what firmware versions you're running? You can see this on the front panel of the inverter in one of the menus (sorry I can't recall where off the top of my head). If you're running an older firmware this can mean that you don't get the full capacity because the SoC tracking is off.

I'd ask your installer to ensure the latest firmware is installed, and also try the battery balancing procedure outlined above...

Yes, the batteries were at 20% when they started charging this morning. Am in the UK and it's a balmy 15 degrees where we live today.

Will head up to the loft and check the firmware.

I will add the system was installed in March 22 but we didn't get any batteries until November 22, where the 2 HV2600's that we paid for we replaced by 2 HV25s. I then bought an additional HV25 last week and it was installed yesterday by an electrician who was working for the installer.

calum wrote: ↑Thu May 11, 2023 5:21 pm What was the SoC of the battery when you started charging it today? Worth noting that 80% of 7.5 is 6, assuming your minimum SoC is still set to 20%...

Given that all the battery modules won't have been balanced on install, the BMS would most likely reduce its assessment of how much charge can go in, which could explain at least part of the difference you're seeing. Also worth noting that the batteries achieve their rated capacity at 25C, I'm guessing if you're in the UK it'll be a bit cooler than that.

Lastly do you know what firmware versions you're running? You can see this on the front panel of the inverter in one of the menus (sorry I can't recall where off the top of my head). If you're running an older firmware this can mean that you don't get the full capacity because the SoC tracking is off.

I'd ask your installer to ensure the latest firmware is installed, and also try the battery balancing procedure outlined above...

Firmware

Master 1.51, Slave 1.02, Comm 1.50
Max charge current is currently set to 35.0A, I was too scared to see how low it went

gard09 wrote: ↑Thu May 11, 2023 5:25 pm So have had a read of the H1-3.7-E user manual.

To get to reduce max charge current it's MENU> SETTING> BATTERY> MAX CHG CUR, think this is correct?

According to the manual, max current is 40A, doesn't give a minimum so I assume there will be a figure I can't go below in the settings? Do you happen to know what that number is?

Thanks again!

I think I've seen on here that it's 4A.

gard09 wrote: ↑Thu May 11, 2023 5:50 pm
Firmware

Master 1.51, Slave 1.02, Comm 1.50
Max charge current is currently set to 35.0A, I was too scared to see how low it went

There will also be a firmware version for the BMS and batteries, useful to a) know what it is and if it can be updated and b) it shows the firmware version for each battery module, so it gives you some indication of whether the BMS can "see" your new one.

Well worth getting the newest versions across everything as, going on my own experiences, it can make a big difference. Not only to things like battery management, but also the efficiency of the inverter, in terms of how much power it takes to run itself.

If your installer can't / won't help you with it, you can raise a ticket on Fox UK.

Hi Callum, thanks for the replies and sorry for the delay in coming back to you.

I emailed Fox Support and was told that my battery firmware was updated remotely, also BMU and BCU (I have no idea with these acronyms mean).

The batteries charged fully today to 100%, I will wait for them to discharge down to 20% and then set the charge rate to 4 amps and charge the batteries (I can't really control if they get fully charged as that is obviously dependent on the weather?).