Battery Question

S

Snowcol

Member
 Glasgow
I see a lot of discussions on here re the importance of a good battery and potential electrical issues. That started me looking at my 2011 23i and checking stuff.
My car starts, runs and everything works perfectly with no dashboard lights on.
However I did notice that the roof would not go down using the key fob when sitting in the garage. It had previously worked off the fob.
So I'm thinking either the battery in the fob is in need of charging up or the roof takes so much power that it needs a fully charged car battery to operate.

It works fine with engine running and buttons in car are used.

So, I put my battery conditioner on the charging post and found it indicating the battery charge below 70%. It took about 48hrs for the light to turn green and show the battery fully charged.

A short drive, engine on off a few times, roof up and down with key fob a few times and the battery conditioner is again showing less than 70% charge and has been on the car again for about 12 hours. It is still not 100%.

However, the car still starts and runs without hesitation.

I am starting to think the battery may need replacing but as I am experiencing no issues/poor cranking etc I wonder if I'm being overly cautious.

I have attached a photo of the battery label. Can anybody decipher the numbers and advise what age it is?

Sorry for the length of this message but your experience/thoughts/advice would be appreciated.

Thanks again20251206_105106.jpg
 
If you look on the other battery terminal it should have a date stamped on the top. If I remember correctly it’s week/year.
 
Thanks Chippie. So it looks like 11 / 17 or 17/11. It's a 2011 car but i doubt it would have the original battery!
If its 11 / 17 then a 2017 battery , now over 8 years old, suggests a new one would be a good investment.
That said, when I checked the voltage it shows over 14 volts when I rev the engine and over 12.5 with the engine off.
Thoughts anyone?
 
Frankly it’s a no brainer…you need to change out the battery sooner rather than later…it’s clearly declining badly..
 
Snowcol said:
That said, when I checked the voltage it shows over 14 volts when I rev the engine and over 12.5 with the engine off.
Thoughts anyone?
Click to expand...
Best thing to do IMO is to monitor the voltage of the battery when it's parked. It will drop a bit as there are things using power all the time, but if it is dropping by more than around 0.1 volts a day without doing anything it may need replacing.

I was having a few fault code issues with our last E89 when we bought it, so of course I immediately changed the battery (they are not cheap for an E89) and registered it. It wasn't the battery that was the problem, so I now have a really good battery sitting in my garage for nothing.

Moral of the story is only change a battery that NEEDS changing. :thumbsup:
 
Snowcol said:
I see a lot of discussions on here re the importance of a good battery and potential electrical issues. That started me looking at my 2011 23i and checking stuff.
My car starts, runs and everything works perfectly with no dashboard lights on.
However I did notice that the roof would not go down using the key fob when sitting in the garage. It had previously worked off the fob.
So I'm thinking either the battery in the fob is in need of charging up or the roof takes so much power that it needs a fully charged car battery to operate.

It works fine with engine running and buttons in car are used.

So, I put my battery conditioner on the charging post and found it indicating the battery charge below 70%. It took about 48hrs for the light to turn green and show the battery fully charged.

A short drive, engine on off a few times, roof up and down with key fob a few times and the battery conditioner is again showing less than 70% charge and has been on the car again for about 12 hours. It is still not 100%.

However, the car still starts and runs without hesitation.

I am starting to think the battery may need replacing but as I am experiencing no issues/poor cranking etc I wonder if I'm being overly cautious.

I have attached a photo of the battery label. Can anybody decipher the numbers and advise what age it is?

Sorry for the length of this message but your experience/thoughts/advice would be appreciated.

Thanks againView attachment 287867
Click to expand...
Hey, interesting stuff! So even though the car starts fine, you’re wondering if that slow fob/roof response is enough to justify replacing the battery—do you think it’s just a weak battery or could something else be going on?
 
Im convinced its the car battery. It's the original 2011 bmw exide 70ah unit.
I have it on a battery conditioner for now and will change it when the car comes off SORN in March/ April
 
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