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Very flat battery.

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G29Z4
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Very flat battery.

Post by G29Z4 » Wed Dec 21, 2022 8:01 pm

When I came to the car today the battery was very flat- absolutely nothing, not even a courtesy light. The door wouldn’t even close. Car garaged in a warm garage, though not used since last Friday (20 miles), so nothing to do with the cold weather.
I tried charging it, again, nothing. It wouldn’t take a charge. Jump started it from a Volvo and it fired up straight away. I drove 6 miles in it, then it took a charge from the charger. 90 minutes fully charged. Everything works perfectly.
But…what caused it?
I went for a new battery (bear in mind the car has only done 9000miles from new) and they were reluctant to sell me one saying that if it’s a software glitch, exactly the same thing will happen again and I’ll be £190 worse off and still with the same problem. A sensible view I thought.
I’ve left it for a couple of hours with no discernible deterioration-it started easily. Going to leave it overnight off the charger.
But what to do with xmas approaching…….?
Your thoughts would be appreciated.

I once had a similar occurrence with an mx5 and never did find the cause. After a jump start the battery lasted for years.


Update!
My son arrived with his code reader and it showed an amazing 65 errors ranging from sidelights, to the diff, to the gearshift, the recent software update and seemingly most else! It was impossible to find the one which caused the problems. Or did the flat battery cause the errors? One by one they were cleared, the car restarted after every few until there were none left. Since then the car has performed perfectly. When up and running it had retained all my settings in iDrive including all my preset radio stations, only the time was wrong.
Bizarre.
Over Christmas it won’t be used, so I wait with baited breath to see if it starts after a few days in the garage.

One response mentioned possible causes which seemed to fit in with events, but maybe I’ll never know.
Last edited by G29Z4 on Fri Dec 23, 2022 9:28 pm, edited 2 times in total.

T_J_G
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Very flat battery.

Post by T_J_G » Wed Dec 21, 2022 8:17 pm

I’d have got a replacement from Tayna. May be worth if it’s not getting used much to put it on a trickle charger. Did you check the voltage across the battery?
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B21
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Very flat battery.

Post by B21 » Wed Dec 21, 2022 8:20 pm

Two separate issues..if you’ve flattened the battery till it’s dead then left for dead it will never ever perform close to the spec that BMW expects…so you will need a new battery come what may…but…

Looks like for some reason that the DME failed to command a full shutdown of all non essential services…and/or something eg comfort access prevented the DME from authorising shut down…

Yet again a code reader required to check that one out…

Any service bulletins related to this matter?
We choose to go to on with this endeavour at this time and do the other things, not because they are easy, but because they are hard..

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Nanu
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Very flat battery.

Post by Nanu » Wed Dec 21, 2022 9:20 pm

If it's still under warranty take it to the dealers and let them find the fault.

Fully charge from totally flat in 90 mins sounds quick, are you sure the battery was showing zero charge when you first put it on the charger?

I know it depends on the charger, but mine was at 50% and it took 5 hours to fully charge
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StanDiego
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Very flat battery.

Post by StanDiego » Thu Dec 22, 2022 7:30 am

G29Z4 wrote: Wed Dec 21, 2022 8:01 pm
But…what caused it?

Your thoughts would be appreciated.

I once had a similar occurrence with an mx5 and never did find the cause. After a jump start the battery lasted for years.
I don't believe you Brits have the dual storage like we do with the 30i in the US, right? I ask because of this from Bimmerpost:

"The (dual storage system) 12 V lithium ion battery features an electronic disconnect switch (ETS) that can switch off the battery to protect it. The voltage at the battery terminals cannot be measured when switched off.
Consequently the (dual storage system) 12 V lithium ion battery is not necessarily faulty if it is no longer possible to measure voltage at the battery terminals.

If the electronic disconnect switch (ETS) has activated, it is necessary to diagnose the (dual storage system) 12 V lithium ion battery using the diagnosis system.

If it is necessary to apply a voltage at the battery terminals to reactivate the electronic disconnect switch (ETS) as per the aforementioned table, this can be carried out using a charger with a suitable voltage setting or by jump-starting with a running donor vehicle. As a result of the insufficient voltage output it is not possible to reactivate the electronic disconnect switch (ETS) using a second battery.

When using a charger it must feature a mode for deep-discharged batteries or manual starting of the charging procedure (so that U>13.6V) as otherwise the battery is not detected and the charging procedure is not started."
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Very flat battery.

Post by B21 » Thu Dec 22, 2022 9:44 am

StanDiego wrote: Thu Dec 22, 2022 7:30 am
G29Z4 wrote: Wed Dec 21, 2022 8:01 pm
But…what caused it?

Your thoughts would be appreciated.

I once had a similar occurrence with an mx5 and never did find the cause. After a jump start the battery lasted for years.
I don't believe you Brits have the dual storage like we do with the 30i in the US, right? I ask because of this from Bimmerpost:

"The (dual storage system) 12 V lithium ion battery features an electronic disconnect switch (ETS) that can switch off the battery to protect it. The voltage at the battery terminals cannot be measured when switched off.
Consequently the (dual storage system) 12 V lithium ion battery is not necessarily faulty if it is no longer possible to measure voltage at the battery terminals.

If the electronic disconnect switch (ETS) has activated, it is necessary to diagnose the (dual storage system) 12 V lithium ion battery using the diagnosis system.

If it is necessary to apply a voltage at the battery terminals to reactivate the electronic disconnect switch (ETS) as per the aforementioned table, this can be carried out using a charger with a suitable voltage setting or by jump-starting with a running donor vehicle. As a result of the insufficient voltage output it is not possible to reactivate the electronic disconnect switch (ETS) using a second battery.

When using a charger it must feature a mode for deep-discharged batteries or manual starting of the charging procedure (so that U>13.6V) as otherwise the battery is not detected and the charging procedure is not started."
Interesting..every day is a school day..
We choose to go to on with this endeavour at this time and do the other things, not because they are easy, but because they are hard..

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