Ok, I have an E39 530D, I use the car every day and have done all winter, a lot of short journeys & a good 130 miles every sunday and Friday. Over the colder days, the car has really struggled to start after 3 days of short trips, but after a decent run it has been fine.

Now, I have just had the week off work (man flu ), the car got parked last Friday after a 130 mile run, so was fully charged. Went to move the car yesterday, and it was dead as a doornail, dash lights but no starter. Jump started it using the underbonnet terminals, stuck it on my drive and charged it overnight using a good battery charger. Checked it yesterday before charging, with the car running at all RPM's it knocks out 14v, so alternator is good (maybe a tad low, should see 14.5-15v on charge?).

Today, as soon as the charger was off, after a 12hr charge on a automatic charger, the battery registerd 11.7v, which to me says it is new battery time. I didn't try to start it, but tonight I went to move the car, and it failed to even turn over..... Checked the battery again, and it is showing 6.5V .... So, dead battery or current drain? Unsure of how old the battery is, been on the car for at least a year, as I have only owned it that long.

I think it points to the battery, but just wondering what you lot think?

 

sounds very much like battery to me as well

 

on my cousins one it was the battery

on my mates 330 it was also the battery (but he had a smaller battery fitted in the first place and the cold weather killed it)

so make sure it's the correct battery for the car before you go and buy the same one again

 

The battery is about the same size as Cuba .. I will be amazed if I can life the fucking thing out of the boot

 

my cousin solved the problem by stickign a jump pack in the boot

he's turn it on when the car was driving so that it not only jumped the car but also charged up while he was using it, then switched it off when he came to the end of his journey

was great for the 8 months the £15 jump pack lasted

 

i have a charger fitted for maintenance charging,bloody air suspension doesnt like to stand still for a week or two.
but still on orginal battery.12 years old

 

Its could also be the Sat Nav (if fitted)

Or the "hedgehog" resistor pack... Thats what went to pot with mine...

This thread helped me loads...

http://forum.bmw5.co.uk/topic/57269-battery-goes-flat/

In fairness from what you've said its more likely than not your battery is fubar, but its worth bearing these niggles in mind....

 

my dads 330 did this, short trips and cold weather she would go flat every 4 or 5 days, battery was only 12 month old too, i got him a solar charger off ebay for £20 and stuck it in rear shelf and run wire to battery in boot, been fine for few weeks now

 

Heater resistor drains the battery all the time ! Hedgehog

 

As said, Heater hedgehog.......mine did the same.

Changed it, bit fiddly but sorted it straight away......... Its next to the clutch pedal (if its not an auto,lol).....

 

It's an auto .. Recon it is the hedgehog? been fine apart from this week

 

Mine just went over night.......never had an issue then one day came out and it wouldnt start as it was flat as. Charged up....Perfect.

Next morning....FLAT.....

Changed the Hedgehog...........all sorted....

 

I have read about them, might try disconnecting it and see what happens. What do they control the fan speed?

 

yer i think so, im sure they just tick over very slowly all night and drain you down........(Just like the misses....lol)

Unplug it and try, the connector is easy to get to as you dont have the full amount of pedals to get in the way....