E92 M3 - AGM battery and "climate change"

[Tony B2]

Yes, it must be the Climate Change wot dun it...;-)

After about 10 days of inactivity, in the heat, I believe my - not very old - AGM battery is toast, which is rather disappointing.

I intended to drive it yesterday but on unlocking (which was fine) the amber "car on a lift" symbol appeared on the centre instrument panel.

Strangely - no low battery warning appeared.

As a precaution, I put the ctek charger on for a few hours.

On subsequently attempting to start, all the normal lights came on with the ignition, at full intensity, including headlights (it was dark) but at the point of pressing the "start" button the second time, a quick flash of the headlights and then ....nothing.

iDrive display said something about a starting system failure, but I did not have time to get a screen shot.

So, this morning I tried again and there was practically no electrical life, even to the point that a polite requestto eject the key from the slot was declined.

Maybe Climate Change got my battery?

Will try again later today, after a few hours of ctek reconditioning....

[illmonkey]

I think you need more time with a CTEK. this is the charging table

BATTERY SIZE (Ah) TIME TO 80% CHARGED
2Ah 2h
8Ah 8h
20Ah 4h
60Ah 12h
110Ah 26h

Granted you probably don't need 80%, but I imagine an E93 M3 has a large battery, call it 80Ah, so will need ~20 hours for 80%. Stick it on overnight and see tomorrow.

BMW's generally act mental with low battery, so it's a good start, especially as you have the charger already.

[Arranguez]

They are useless with batteries. I washed mine yesterday and left the key in the ignition so it was “on”. Only just about started after 90 mins for the quick run round the block to dry the discs.

[Arranguez]

They are useless with batteries. I washed mine yesterday and left the key in the ignition so it was “on”. Only just about started after 90 mins for the quick run round the block to dry the discs.

[InitialDave]

My Z4 can throw a warning too after that long left unattended, if it's at home I've taken to leaving the ctek (in AGM mode) on it if parked up for a week plus and that seems fine.

[bgunn]

Arranguez said:

They are useless with batteries. I washed mine yesterday and left the key in the ignition so it was “on”. Only just about started after 90 mins for the quick run round the block to dry the discs.

You left the car on for 90 minutes without the engine running? I wouldn't call that 'useless' - the current draw of the DME, iDrive and other core car systems are in the region of about 40-45A - so a typical very fully charged 90Ah battery will last two hours before being completely flat. The intelligent charging of the car won't actually fully charge the battery to 100% SoC, in order to keep the battery healthy.

Generally, when people change batteries on modern BMWs they neglect to:

1) Register the battery replacement - to reset the battery characteristics in the DME
2) Ensure the correct battery is fitted - often a cheaper flooded cell battery is put in instead of an AGM
3) Ensure the correct capacity battery is fitted - reprogramming the car to suit the capacity fitted

Once all of the above are correctly dealt with, they're fine.