How to soc settings

[Ftv_Sicily-Isle]

Hi everyone, it’s my first time writing.
I have a 4.1kw photovoltaic system consisting of:

10 panels canadian solar 410wp
Foxess inverter H1AC1
2 Mira Hv25 battery modules
1 module of battery control

I would like to set the maximum battery discharge threshold at 90%.
However i'have trouble opening the pop-up from pc for time out ad same situation if i try from the smartphone
See the screen shot

It's correct to set the threshold (min soc) to 10 ?
Why also set the on grid threshold ?
Many thanks
Alessandro

[calum]

Do you want the battery to not charge above 90%? Or not fall below 90%? I'm not clear. There is a Max SoC setting but it only applies to charging from the grid, if there is enough solar PV available the battery will charge to 100% from it.

There's two MinSoC settings, as you might want a different threshold if you're using the system offgrid as opposed to grid connected. The early firmware in the BMS wasn't great at managing battery charge levels so some people were warned by their installers not to go below 20% as a safety buffer. That said, if you're on the latest firmware for everything then 10% is a sensible minimum (and is also the lowest that the BMS will allow).

[Ftv_Sicily-Isle]

First of all, thank you for your answer.
The theory says that to increase the life of the batteries these must not go below 10% and above 90% of their charge.
If the above is true, then I wanted to impose that the battery does not drain more than 10% and does not charge more than 90%.
I understood that setting the threshold of 10% is done through the soc settings (min soc).
Is it possible that the 90% threshold is already set by default and I’m not able to verify it?

[calum]

As far as I am aware there is no way to stop the battery charging above 90% from solar.

However the "don't charge above 90%" guidance sounds like it is meant for nickel cobalt lithium batteries, rather than the iron phosphate type used by Fox' home batteries. I understand that these cells don't "mind" being charged to 100%.

[H1MKK]

The easiest way to change the SOC settings is in the web, rather than the phone app (My experience is that APP is not 100% reliable, while the Web is - https://www.foxesscloud.com) when my Batteries were installed, the installer insisted on a 20% minimum SOC, although 100% was set for the charge. I think the previous post is correct, Lithium is fine with 100% charge.

Regarding the 20% minimum. SOC, I have changed this to 15% as I can find nothing that says it is a safety or a health issue for the batteries, and @ 20% SOC, I am allowed to use 1.5 batteries in my set up…..which I think is unreasonable.

[calum]

I suspect your installer insisted on a 20% minimum SoC because of the somewhat "under baked" early firmware for the batteries and BMS. This could see SoC tracking problems lead to significant drops in reported SoC under minimal actual load.

The latest firmware is not perfect but it is much improved and should enable you to set the MinSoC to 10% without a concern. Don't change the setting until you've got the firmware updated though!

[Miki]

I suspect your installer insisted on a 20% minimum SoC because of the somewhat "under baked" early firmware for the batteries and BMS. This could see SoC tracking problems lead to significant drops in reported SoC under minimal actual load.

The latest firmware is not perfect but it is much improved and should enable you to set the MinSoC to 10% without a concern. Don't change the setting until you've got the firmware updated though!

Hello calum,
any more details on the issues with older firmware in relation to minimum SoC?

My batteries completely discharged and went offline about a year ago, the installer claims it must be due to some high power input device I have at home (which I don't).

Thanks!

[calum]

Hi there, not much more to say than already said - the newer firmware helps the batteries and firmware work better together and stick to the SoC limits that you set, as well as making the changes in SoC more predictable because the BMS has a better idea how much energy is really left in the batteries.

Unfortunately some installers do not understand these systems properly, or they will take something that happened once and apply it to all situations. Getting your batteries and BMS on the latest firmware, keeping them at a "happy" temperature and making sure that they get fully charged and discharged from time to time will all help.

I hope you were able to wake up your batteries soon after they went offline?! If they have been sat totally discharged for that long they will be seriously damaged by now...hopefully not the case!