Ford Focus ST '22 Battery Drain!

[Gus T]

1 minute ago, Stevie H79 said:

Thanks for the replies. How does one go about changing the SOC with Forscan? It's not something I'm familiar with. As you stated the dealer isn't going to perform it so it would be a waste of time going there. I'm edging towards going down the charger route simply for the ease. Also altering the SOC you say can affect emissions, does that not make it prone to MOT failure? 

I too would like to know the answer to this 🙏

[Coley666]

19 hours ago, unofix said:

Ford know there is a problem but their hands are tied by EU/UK emissions rules. The cars alternator causes a significant load on the engine which causes more emissions. Therefore car manufactures have set the default charging rate to a maximum of 80% to help them meet the impossible emission targets.

Increasing the charging rate to 95% helps keep the battery healthy but would mean that they would fail to get type approval for the vehicle. Ford dealers are prohibited by Ford from altering the SOC. There is of course nothing to stop individual owners using FORScan and adjusting the charge rate to 95% and living 'happily ever after' 😀

I'm on my way so you can do this for me 😏 

Just kidding 😂 

All joking aside, I unplugged my 12v usb charger for my dadhcam each time I got out the car, and over the last week or so the lights issue has happened ONCE! so I am very inclined to believe the fact that my battery just isn't getting charged up enough by my daily use. 

I didn't ring the dealer in the end due to, well, life 😅 and in all honesty I don't think I'm going to bother. 

The father-in-law has a battery tester and charger, so I'll drop round for an ear full and a test/charge before anything else. 

 

Thanks all. I'll keep you posted as to how I get on. 

[unofix]

2 hours ago, Coley666 said:

I'm on my way so you can do this for me

Do feel free to pop round, I've not had the chance to work on a Mk4.5 as yet. 👍

[unofix]

4 hours ago, Gus T said:

I too would like to know the answer to this

For those worried about the affect that it could have on the emissions, don't !!

The tiny fraction of a percent that it might change is so small that outside of a laboratory test it would just not be possible to measure. What you have to remember is that much of what is done in the same of saving emissions is all just hype forced upon the manufacture by EU bureaucrats in order for the car maker to be able to get a type approval under sterile lab test conditions.

As far as MOT testing goes, as said above any change would just not be possible to measure. They would have to have a "Standard Battery" pre-charged to an exact value so that they could determine what the load was on the alternator during an emissions test.

[Stevie H79]

That's good to know although the MOT isn't due till the end of October 2025 and I don't plan to have the car then. I'm still in the dark as to how this Forscan battery SOC can be changed I'd Ford dealers are reluctant to it. Obviously I want to avoid paying hundreds of pounds out 

[Gus T]

2 hours ago, unofix said:

For those worried about the affect that it could have on the emissions, don't !!

The tiny fraction of a percent that it might change is so small that outside of a laboratory test it would just not be possible to measure. What you have to remember is that much of what is done in the same of saving emissions is all just hype forced upon the manufacture by EU bureaucrats in order for the car maker to be able to get a type approval under sterile lab test conditions.

As far as MOT testing goes, as said above any change would just not be possible to measure. They would have to have a "Standard Battery" pre-charged to an exact value so that they could determine what the load was on the alternator during an emissions test.

Thanks for the info! 👍👍

[RaduF86]

Hello everyone,

I am new to this forum and I see there is a lot of very useful information, so I shall post here since my issue is somehow related to the deep sleep / battery charging/draining problems I've read about here.

Long story short, I have a 2020 Focus mhev which had a very normal behaviour for 3 years, and by that I mean the vehicle entered deep sleep after a few days (usually around 1 week) of not being driven.

However, this month I had it serviced (the normal 60.000 km routine service) + a reapplication of rtv sealant on the timing chain cover. Since this service the car enters deep sleep within 20 minute after locking it.

So naturally I started checking the voltage in the morning, as I thought it is a very good moment to catch if the car had indeed some battery drain problems. So now the results don't add up for me, and I hope you can give me some idea on what to check next, or what to do:

Every evening I left the bonnet opened (but locked all doors, and the car of course) so in the morning I could take a voltage read without opening and waking up the ECUs. Every morning the voltage was between 12.3 and 12.5V (so around 80% SOC according to the table I saw posted by @unofix).

Finally, on Saturday I received a diag tool and installed forscan and this is where things got confusing. The BCM shows a 30% SOC. battery age is 1241 days (original battery).

I started and let the engine running while monitoring the charging parameters: Voltage output by DC/DC = 14.8 - 14.9V, Battery current = 1 Amp (so this would be charging current). I let it running for some time and the SOC reached 33%. I wanted to see if the BCM actually updates the SOC, which it does.

No DTC present (history nor active) for the charging system.

I locked the car on Sunday and haven't touched it for the past 24 hours hoping the BCM shall recalibrate the SOC. I didn't check the sleep current drain because I do not have a clamp amp meter yet, so I don't know if the sleep current falls under 100 mA.

 

Any suggestions on what to do next and if anything I have mentioned seems strange to you?

Thank you very much!

 

[TomsFocus]

30-33% SOC seems out of sync with the measured battery voltage.  Not the first time we've seen this happen.  Fords fix was simply to disconnect the battery for an hour or so iirc.

[RaduF86]

Just disconnect the battery? I can try that for sure.

Is it better to remove the battery clamp with the BMS on it, or remove the ground cable from the chassis connection point? Any idea what the torque for the chassis connection point nut is?

Thank you for your support!

[alexp999]

6 minutes ago, RaduF86 said:

Just disconnect the battery? I can try that for sure.

Is it better to remove the battery clamp with the BMS on it, or remove the ground cable from the chassis connection point? Any idea what the torque for the chassis connection point nut is?

Thank you for your support!

You need to remove the battery clamp, if you just disconnect the chassis point, the BMS stays connected. You're trying to force restart (not reset) the BMS module so that it has to relearn the SoC.

[RaduF86]

Understood! I will try this way and see what happens.

Thank you for your very fast replies!

[unofix]

3 hours ago, RaduF86 said:

Any suggestions on what to do next and if anything I have mentioned seems strange to you?

Hi, this is just a thought, I don't know if this is the cause but perhaps it could be.

If when the car was in the garage they had it connected to a battery saver (a bit like a charger), then depending on where they connected the negative of the battery saver it could well have confused the battery Monitoring System (BMS). If was detecting a large current draw while the vehicle was been serviced it would assume the current was being supplied by the battery, when in fact it was being supplied by the battery saver.

As I say these are just thoughts and i have no evidence to support the idea.

The BMS will normally recalculate the true State Of Charge (SOC) between 24 and 48 hours. Driving the car does seem to speed up the process.

[RaduF86]

Interesting point. I did not think of this possibility. 

After taking the car and seeing it entered deep sleep soon after locking it, I was sure the battery was discharge due to the service. So I drove it every day for about a week. Seeing it doesn't help I started measuring the voltage each morning like I mentioned above and saw it looks quite good. I also drove it after checking the voltage. Seeing this didn't help, I finally bought a DiagTool and checked the SOC.

I will let it sit more than 48 hours maybe it recalculates the SOC. So Wednesday evening I shall check again with FORscan and see what I get.

I find it strange stuff like this happens, but I am not really surprised. I did have 3 full years of zero issues with this car, and I hope this to be just an estimation issue on the BCM side.

Cheers! 

[RaduF86]

Hello,

Short update after mode than 48h of not touching the Focus:

I opened the car, the brake-by-wire unit started its normal tests, the Sync 3 displayed the "Turning off to preserve battery" and I connected FORscan. You can see above the measurements.

2.00 Amps current draw with ignition off seems very reasonable to me (this is without the brake system running its test)

12.2V battery voltage with 2 amps current being drawn also looks good to me. So in worst case scenario I would have expected the SOC to be 50-60% at this voltage.

And SOC 31% does not look good to me. It looks like the BCM did not recalibrate the SOC. Could it be that because of the deep sleep the BCM does not wakeup to recalibrate?

Next step I am planning to take are to measure the sleep current (after I receive the non contact amp meter) just to see if for some reason the current never falls under 100mA

Then I shall hook up my charger Positive on battery, Negative on chassis connection point, hook up FORscan and start charging with the BCM awake until I get close to 80% SOC. Only downside with this idea is that my charger can output max 3.8Amps continuously and with the -2.0Amps current draw, it will take quite a while to have things back to normal.

But I don't have any other ideas, except disconnecting the battery and hoping the SOC is recalibrated upon reconnection.

Of course at that voltage the car starts really smooth (as it always did in fact). And the funny fact is that Start/Stop is working perfectly because the 48V battery is nicely charged 😄, but the AC is not turning on because of the 12V wrong SOC. Isn't this a paradox 😄.

Here is the voltage and current sags as the engine cranks. Right after the BISG and DCDC push the current up to 34.0 Amps and voltage goes up to 14.8V. I ran the engine for about 20 minutes and the voltage remains steady at 14.8V while current slowly goes down to 1 Amp.

Blue trace shows the SOC increase from 31% to 32%. After a few minutes of charging, the SOC reached 33%.

Cheers!

[unofix]

This all seems odd. No reason to need to keep the ignition on while charging, the BMS will know and sense the current flow in to the battery.

Give it a full 12 hours charge and see what the SOC is then. If it has gone up past 60% then keep charging otherwise I think you may have to replace the battery and reset the BMS.

[RaduF86]

It does seem very odd indeed!

Left the boonet open over night so I could measure the voltage in the morning without waking up the car (for sure it is in deep sleep):

I used Peak-Hold function to be able to take the photo, but I also measured without the Peak-Hold and it is indeed 12.4V.

So I believe there is no unwanted current drain otherwise I would have expected to read a lower voltage. Also, 12.42V corresponds to the 80% SOC.

 

@unofix just for me to understand, the SOC is estimated by the BMS (the sensor hooked to the battery), or by the BCM? If it is the BCM it would explain why it is not recalibrating while in deep sleep. If it is the BMS then that is a smart sensor which should always stay awake no matter if the car is in deep sleep or not.

[Tizer]

1 hour ago, RaduF86 said:

It does seem very odd indeed!

Left the boonet open over night so I could measure the voltage in the morning without waking up the car (for sure it is in deep sleep):

I used Peak-Hold function to be able to take the photo, but I also measured without the Peak-Hold and it is indeed 12.4V.

So I believe there is no unwanted current drain otherwise I would have expected to read a lower voltage. Also, 12.42V corresponds to the 80% SOC.

 

@unofix just for me to understand, the SOC is estimated by the BMS (the sensor hooked to the battery), or by the BCM? If it is the BCM it would explain why it is not recalibrating while in deep sleep. If it is the BMS then that is a smart sensor which should always stay awake no matter if the car is in deep sleep or not.

A few thoughts of mine.

12.4V is not fantastic, if my battery was showing that while asleep and there was no excessive Current Draw I would think about changing it. The battery probably got deeply discharge when it was in the Garage and that has damaged it.

With the car being a MHEV, it may be that the figures in FORScan are not correct for these cars, I don't know if other people with the same car are showing spurious figures as well.

The one thing that you can do is the do a Module Reset of the BCM with FORScan, it may recalibrate the BMS figures. Disconnecting the battery for 20 minutes may do the same job. 

 

[RaduF86]

"With the car being a MHEV, it may be that the figures in FORScan are not correct for these cars" - This did not cross my mind. I had hopped that the data base of forscan is up to date since the MHEVs have already 4 years on the market.

I shall come back with updates after I try recharging the battery. 

It is a pitty I never measured the battery before all this started. At least I would have had a reference point for all these tests and measurements :D

Thank you for all your suggestions!

 

[Tizer]

38 minutes ago, RaduF86 said:

"With the car being a MHEV, it may be that the figures in FORScan are not correct for these cars" - This did not cross my mind. I had hopped that the data base of forscan is up to date since the MHEVs have already 4 years on the market.

I shall come back with updates after I try recharging the battery. 

It is a pitty I never measured the battery before all this started. At least I would have had a reference point for all these tests and measurements 😄

Thank you for all your suggestions!

 

For reference, in the first few years my non MHEV Focus my battery Voltage measured at least 12.5V even though my SOC was limited to the default 80%. I now have a new battery and set my Target SOC to 90% like others on here. I haven't checked my sleeping Voltage recently but my SOC hovers around 90%.

You probably know this already but when you do get your Clamp Meter it takes almost a full hour before the car finally goes to sleep.

It is not unusual for some of the data in FORScan to be incorrect, but they will only entertain people with a Paid Licence and if they see that the resting Voltage is only 12.4 then their thoughts may be the same as mine and they will probably suggest the same as me.

 

 

[unofix]

11 hours ago, RaduF86 said:

just for me to understand, the SOC is estimated by the BMS

The sensor that is installed in the negative battery lead is little more than a current shunt and amplifier. It detects current flow and whether it is going in to the battery or coming out.  The actual calculations of the SOC is done by the BCM.

[alexp999]

This says it’s all done on the bms. 
 

https://www.bosch-mobility.com/en/solutions/sensors/electronic-battery-sensor/

[unofix]

11 minutes ago, alexp999 said:

This says it’s all done on the bms.

The measurements are all done on the BMS and the information is then sent to the BCM. The BMS has no direct control over the alternator charging.

[alexp999]

5 minutes ago, unofix said:

The measurements are all done on the BMS and the information is then sent to the BCM. The BMS has no direct control over the alternator charging.

I just meant the SOC is calculated on the BMS. 

[RaduF86]

From the BMS reference above:

"The EBS measures the current using a shunt and determines the battery's voltage and temperature. These base parameters are required as input parameters for the integrated battery state detection (BSD) among other things. On that basis, the BZE algorithm predicts the battery's state of charge (SOC), the state of function (SOF) and the state of health (SOH)."

I also understand that the BMS makes some measurements and sends the information via LIN to another ECU (BCM in Ford's case) which in fact estimates the battery condition. Which means the BCM must be awake to do so. Which means that either while in deep sleep it wakes up regularly to recalibrate or it doesn't to ensure battery is not drained further so no SOC recalibration.

 

In my case this morning the Voltage was 12.41V (yesterday morning it was 12.42V) so very little drain. In fact, with the non contact clamp meter I measured the deep sleep current drain to be approx 50 mA. It is not a professional tool so most likely it has lower accuracy than a profi one, but still what it measures is well below the 100mA stated as the value under which the SOC is recalibrated.

 

 

[Tizer]

5 minutes ago, RaduF86 said:

I measured the deep sleep current drain to be approx 50 mA.

That is the maximum that that Ford prescribe.