[HighlandPete]

Originally Posted by am549

I am slightly concerned about the battery status in mine. Was in for a service last week and I mentioned about the low battery warnings to be told it was fine. Went out the other night (was bitterly cold outside), drove for about 20 mins averaging 40mph, stopped and within a minute of engine off, battery warning message and all the electronics shut off seconds later. It's back on the charger again today to see if that sorts it out. This can't be normal surely? The wife's 69 plate A class does less mileage than me currently and stop start etc. all work fine.

There are so many variables, it is difficult to know if your car's state can be defined as 'normal' or not.

For example, what is a definition of 'fine'? Everything working as it should, but battery in a low state due to lack of use?

Remember driving a few miles won't change the battery SoC very much, unless the battery is very low. Then it only charges up until a specific threshold, before it goes back to full intelligent alternator control.

I've mentioned before that I experimented with checking voltage before a run of around 25 miles, voltage was still the same after the trip. A couple of starts, use of electrical consumers as normal, there wasn't any measurable improvement in SoC for the battery.

Our colder temperatures haven't helped, we may be getting warnings that wouldn't be triggered in warmer weather.

[Carjack]

On starting up last week I got a warning message ‘Battery discharged’ ‘Use key’.
So I bought a CTEK 5.0 battery charger and left in on most of the day and all night.

In the morning I started the car and again I had the warning message ‘Battery discharged’ ‘Use key’.
Since I have left the car hooked most of the day and all night but on start up still the warning message will not go away.

Using a multi tester whilst charging, the voltage is 12.68v, OK as I assume the CTEK is trickle charging.
However, when I unplug and remove the CTEK the voltage drops to 12.36v. I was hoping it would stay at 12.68v.

Surely this cannot be right and I therefore suspect the battery is not holding a charge or theres a leak somewhere. Alernator?

Anyone any ideas as I find all this a bit frustrating as the car is not 2 years old yet and has only done 7000 miles.

[HighlandPete]

Originally Posted by Carjack

Using a multi tester whilst charging, the voltage is 12.68v, OK as I assume the CTEK is trickle charging.
However, when I unplug and remove the CTEK the voltage drops to 12.36v. I was hoping it would stay at 12.68v.

Unlocked, or locked and asleep? My car, there can be a 0.3 - 0.4V difference when unlocked. Drops on unlocking.

[Carjack]

PS to my post above.
During the bitter winter of 1962/1963 when snow lasted with heavy frost from Boxing Day to early March I drove every day to work, except a few days when the roads were not cleared, a 1962 Hillman Minx Mark 111C and had no trouble with the battery whatsoever.
So to have trouble in this pussy winter with a high teck BMW is baffling.
I can only assume in North America the battery and alternator is upgraded somewhat!

[crowdedhouse]

Originally Posted by Carjack

In the morning I started the car and again I had the warning message ‘Battery discharged’ ‘Use key’.
Since I have left the car hooked most of the day and all night but on start up still the warning message will not go away.

Is it the battery in the key fob?

(disclaimer I drive a G01 )

[xenon]

12.36v at the battery is fine.

[HighlandPete]

Originally Posted by Carjack

PS to my post above.
During the bitter winter of 1962/1963 when snow lasted with heavy frost from Boxing Day to early March I drove every day to work, except a few days when the roads were not cleared, a 1962 Hillman Minx Mark 111C and had no trouble with the battery whatsoever.
So to have trouble in this pussy winter with a high teck BMW is baffling.
I can only assume in North America the battery and alternator is upgraded somewhat!

We had conventional charging in those days. Plus going for a run could charge the battery to near 100% SoC. When we switched off, there was nothing on the car to drain the battery over time.

Technology can be fine in ideal conditions, but... the car is never totally switched off. We also have the the term "driving profile" these days. This past year, many of us have dropped out of having an ideal driving profile.

[Carjack]

Originally Posted by crowdedhouse

Is it the battery in the key fob?

(disclaimer I drive a G01 )

Is was the key fob battery! Battery changed, message gone!
Many thanks for your post.
The key fob never occurred due I suppose they usually last quite a few years, in my past experience with BMW’s.
Cheers!

[Carjack]

Originally Posted by xenon

12.36v at the battery is fine.

This good! Thanks for your advice!
Now all is OK thanks to ‘Crowdedhouse’ post advising of the fob battery!

[HighlandPete]

Originally Posted by Carjack

This good! Thanks for your advice!
Now all is OK thanks to ‘Crowdedhouse’ post advising of the fob battery!

When I read the post on querying the fob battery, I reread your full post and noticed I'd missed the 'Use Key'. Pleased you picked it up and tried a new battery.

I've had that warning on my car, and yes, key fob battery was required.

[xenon]

And on earlier (E series) cars the key was charged whilst in the slot. Nowadays a spare CR2032 battery is worth keeping on hand.

[seelark]

I'm sure I used to put the key in the door to unlock it, and then in the steering column to start it 🤔 Then have to lean over to open the passenger door if required?

The battery in the key fob was for the silly little light to help find the door lock 😭

[xenon]

I remember those days. Had a Vauxhall Astra with the torch in the key - the ultimate in driver convenience.

[am549]

Originally Posted by HighlandPete

There are so many variables, it is difficult to know if your car's state can be defined as 'normal' or not.

For example, what is a definition of 'fine'? Everything working as it should, but battery in a low state due to lack of use?

Remember driving a few miles won't change the battery SoC very much, unless the battery is very low. Then it only charges up until a specific threshold, before it goes back to full intelligent alternator control.

I've mentioned before that I experimented with checking voltage before a run of around 25 miles, voltage was still the same after the trip. A couple of starts, use of electrical consumers as normal, there wasn't any measurable improvement in SoC for the battery.

Our colder temperatures haven't helped, we may be getting warnings that wouldn't be triggered in warmer weather.

So it's been into BMW (for something else that didn't get rectified during service so had it looked at again) and they've said it's fine. I guess I'm just trying to work out what the best way of keeping the battery "healthy" is whilst it's not getting it's regular 100ish miles a week. I am still amazed how quickly it does seem to drop off after being fully charged (fully charged according to the ctek) vs the wife's A class which hasn't needed charging at all.

Guess I'm interested to see how everyone else has been getting on with theirs. Probably averaging around 10 miles a week currently which I know doesn't help things, along with the cold weather.

Edit - Just got it back from BMW and in the notes it states only charged to 40-60% due to lack of use. On 15/02 I charged it with the ctek to stage 7 (float), which I'm assuming means the battery is fully charged. It can't be right to go 40-60% in less than 2 weeks right?

[Seaford]

A small addendum to this thread……I have a CTEK conditioner…..it stays on the lowest red light with bonnet open……..but goes through the cycles quite quickly with the bonnet shut.

I would guess it is doing it’s job with the bonnet open but there is some equipment drawing a charge that fools the conditioner giving false readings? With a bit of gymnastics it is possible to get the CTEK cable through an opening down by the front suspension…..there is a handy little slot by the headlight where the cable can be run much easier…just take care with placement of cable when closing the bonnet!