Is my new battery charging correctly?

[vinaltap]

Due to the now resolved issue with my head unit, my car battery was severely drained several times and needed replacing. 

I've replaced the battery with a new Bosch S4 E10 and charged it fully before fitting it. I did a 2 hour journey on Sunday and noticed, using my plugin cigarette voltage meter, that when driving the voltage is at 12.1 V. However, when I take my foot of the gas the voltage rises up to 14.4 V momentarily until the car is back into idle speed. I assume this is due to the battery management system, but as I have only had old school cars I'm not aware of the specifics of this system. Is this normal for a MK3 focus diesel? 

[Luke4efc]

Have you reset the BMS after fitting the new battery?

Your plug in meter isn't an accurate way of measure the voltage. You should really measure directly from the terminals.

[vinaltap]

I reset the BMS last night and did a 2 hour journey afterwards, the voltage output didn't change though.

Yeah fair enough, I'll put my meter on the battery tonight. Perhaps I'm being a little over concerned, but I want to avoid ruining this new battery as well.

How do you bring up the voltage on the  dashboard? I will also give that a go. 

[jlawes20389]

Hold the ok button on the steering wheel down then turn the ignition on while keeping it held. That will go into the test mode then scroll through the menu.

Hold the ok button again to come out or just turn the ignition off.

[unofix]

The intelligent charging system is not always as cleaver as it likes to think it is. On most Fords these days the system is designed to only charge the battery to 80% of it's capacity. There are some cases of the charge percentage being as low as 70% but not normally in the UK.

When the engine is under acceleration then the charge system will reduce the amount of power comming from the alternator (reduces the drag) and alllows the voltage to fall to just over 12V. During deceleration/engine overrun the charge system will adjust the alternator to produce maximum power and the voltage will go up to about 13.6V. This also increases engine brakeing due to the drag caused by the alternator.

Using ForScan you can adjust the battery charge level. If you do lots of short runs with frequent stops and starts then I would adjust the charge level to 90% to help maintain the battery.

[vinaltap]

Okay so I used my battery tester which states that the battery is 12.22 Volts (36% state of charge). The dashboard states 11.8 Volts.

When I tested the alternator voltage during idle, the tester said no output. As mentioned previously, it seems to only output when I let my foot off the gas for a few seconds when driving.

[Frembrit]

As Unofix has mentioned, the Smart charge mainly charges when the engine is not under load (unlike old school cars), basically when you lift off the accelerator pedal, this is to help save fuel and emissions (something like that). So with that in mind what does your voltmeter say when you are off the accelerator pedal and going down a hill? (in gear or course). And what length of journeys do you normally make?

[unofix]

1 hour ago, vinaltap said:

As mentioned previously, it seems to only output when I let my foot off the gas for a few seconds when driving.

That is how the smart chargeing system works. Think of it a bit like regenerative braking on an EV. The alternator will only provide the minimum power needed during idle or acceleration.

Do I think it is a good idea ? "No I don't" but thats what we have to live with. Use Forscan and change the battery charge to 95% if you don't do many miles or your car stands for days at a time doing nothing.

[isetta]

On my brothers focus 1.8tdci we thought it needed a new alternator due to minimal alternator output. When removing the alternator we found it was just the pulley. That pulley had a one way clutch within that failed so the pulley was not turning the shaft as fast as it should. Replaced pulley, all was fine then. I don’t know if yours has a pulley like this.

[YOG]

10 hours ago, unofix said:

.......... Using ForScan you can adjust the battery charge level. If you do lots of short runs with frequent stops and starts then I would adjust the charge level to 90% to help maintain the battery ..........

3 hours ago, unofix said:

.......... Use ForScan and change the battery charge to 95% if you don't do many miles or your car stands for days at a time doing nothing ..........

 

Can you explain the ForScan procedure to increase the battery charge level, please? Thanks.

Thanks.

[unofix]

3 minutes ago, YOG said:

Can you explain the ForScan procedure to increase the battery charge level

Just follow the instructions in this YouTube video, sorry it is in German but it does have English Subtitles

 

[mjt]

He connected his charger to the battery negative terminal instead of the body earth point. We've been repeatedly told this will prevent the state-of-charge sensor from registering the fact the battery has been externally charged.

[unofix]

1 hour ago, mjt said:

He connected his charger to the battery negative terminal instead of the body earth point

Yes you are correct, I noticed that as well. Maybe it doen't apply to german models after all most rules don't apply in europe. 🤣

[pcaouolte]

1 hour ago, mjt said:

He connected his charger to the battery negative terminal instead of the body earth point. We've been repeatedly told this will prevent the state-of-charge sensor from registering the fact the battery has been externally charged.

It doesn't matter for long as the BMS system recalibrates the stored level of charge, by checking the battery voltage, when the car is left unused for several hours.

[YOG]

To be fair to him, it is mentioned in the video: