Hi,

Yep, another battery thread…

I have a 2020 Fiesta ST-Line mild hybrid. The standard Ford battery failed about 12 months ago and I had Halfords replace it with a 75Ahr one.

Last week I started to get the ‘system off to save battery’ warning.

I charged it a week ago with my Maypole 7423 smart charger and it went away but has now returned. I had the battery checked at Halfords today and it showed 12.8v with the engine off so I think the battery is sound.

I think I’ll bite the bullet and change the target state of charge from the default 80% to 95% using Forscan as recommended in many threads on here.

I can’t find any independent garages with Forscan here in Cheshire so I’ll tackle it myself. I believe I need to download Forscan to a Windows laptop AND an extended license to be able to write changes. I’ll also get the recommended OBD/USB link cable which I’ve seen on the forum.

Is there anything I need to do BEFORE I change the target state of charge?

Is there anything I need to do AFTER I make the change - reset the BCM, for example.

I can’t find a YouTube tutorial that deals with this specifically other than the one posted by a German chap but it has English subtitles so it is helpful.

Anything else I should know- it’s dead easy, yes….?

Many thanks,

Jeff

11 hours ago, jhiker said:

I believe I need to download Forscan to a Windows laptop AND an extended license to be able to write changes.

Correct

11 hours ago, jhiker said:

I’ll also get the recommended OBD/USB link cable which I’ve seen on the forum.

Yes, the V-Linker or OBDLink-EX cable. I prefer the OBDLink

11 hours ago, jhiker said:

Is there anything I need to do BEFORE I change the target state of charge?

I would fully charge the battery again and reset the BMS with FORScan and save the standard configuration before making any changes (go into configuration & programming, select BCM not BCM asbuilt, go to bottom of screen and click save all)

11 hours ago, jhiker said:

Is there anything I need to do AFTER I make the change - reset the BCM, for example.

No, module will reset itself.

Make sure laptop has an internet connection BEFORE first time connect to vehicle

Make sure Laptop is connected to a power source, never risk programming changes on battery power

To change Battery SOC:

Go into configuration & programming, select BCM not BCM asbuilt

Scroll down until you see Battery SOC or Charge level

Open window at side and change figure to 95%

Go down to bottom of screen and click "write all"

Then make any other changes that you want (like drive away locking (autolocking) etc)

Do each change one at a time

Thank you for that very helpful reply.

‘I would fully charge the battery again and reset the BMS….’

I’m a little confused about BCM and BMS - what’s the difference please?

Saving the current standard configuration allows you to revert in case of a *****-up, is that correct?

‘Make sure laptop has an internet connection BEFORE first time connect to vehicle….’

What’s the reason for this. Once Forscan is installed and running on the laptop does it still need internet connection while you plug it in to the OBD port and make the changes?

14 minutes ago, jhiker said:

I’m a little confused about BCM and BMS - what’s the difference please?

BCM is the Body Control Module. That handles various electronic features including windows, mirrors, central locking, etc.

BMS is the Battery Monitoring System. That only deals with battery charge.

You need to reset the BMS with a new battery so the battery charge rate is calculated correctly. But permanently changing the functionality, such as increasing target SOC, is done inside the BCM.

Sorry, presumed you knew.

@TomsFocus has clarified for you

1 hour ago, jhiker said:

Saving the current standard configuration allows you to revert in case of a *****-up, is that correct?

Absolutely!
Before you make any changes in any module save the factory condition.

If it all goes wrong you can just load it back and click write all.

If you need any help just reach out👍

Thank you.

‘Make sure laptop has an internet connection BEFORE first time connect to vehicle….’

What’s the reason for this. Once Forscan is installed and running on the laptop does it still need internet connection while you plug it in to the OBD port and make the changes?

you dont need internet while connected to vehicle just make sure forscan is up to date / latest version / licence loaded first before venturing outside

On 4/17/2026 at 11:26 AM, jhiker said:

Thank you.

‘Make sure laptop has an internet connection BEFORE first time connect to vehicle….’

What’s the reason for this. Once Forscan is installed and running on the laptop does it still need internet connection while you plug it in to the OBD port and make the changes?

It downloads the relevant bootloaders for the modules, less risk of anything going wrong when programming