Dead battery on e39 M5

[JerseyS2000]

Hi guys

I posted a thread after Xmas concerning jump starting a dead battery. This worked fine twice but after the latest cold spell, the battery is now totally dead and needs replacing.

I am going on holiday for over 3 weeks very shortly and am wondering if the car is OK to sit with a dead battery for all that time.

As long as it doesn't 'hurt' the car in any way (ie ECU, alarm, whatever), it seems silly spending a chunk of money now to buy a new battery and risk it being dead by the time I get home, especially in this cold weather. Oh, and I don't really trust anyone to drive the car whilst I'm away to keep it 'topped up'.

Any thoughts would be welcomed.

Thanks

Ben

[MarkwG]

I'd check that you can get into the drivers door & boot without the electric, just using the key, otherwise I reckon it would be fine. I'd be curious about what's killed the battery, though?

[Neil.D]

Charge the battery up then disconnect it whilst you are away. Recharge it then start the car when your back. A dying battery connected to your car would be undesirable.

[belleair302]

Are you not able to buy a ctek trickle charger and keep your car plugged in whilst away?

[JerseyS2000]

The car isn't parked near my house so there is no power source to run a trickle charger from.

Unless they make solar powered ones of course.

I can open the driver's door but not the boot. Which raises any interesting point for getting at the battery eventually. It is in the boot, yes?

[Neil.D]

Yes in the boot under the carpet, then under the plastic cover and then under the foam spacer.

[belleair302]

You can buy solar battery chargers that plug into your cigarette lighter. How effective they are is anybodies guess.

http://www.theultimatefinish.co.uk/solar-technolog...

[gavinbailey]

You should be able to open the boot with the key. I had a similar problem with a dead battery and thought I couldn't open the boot with the key. I called out BMW emergency service who promptly opened the boot with my key. All you do is to turn the key clockwise (I think), past the detent. It's fairly stiff as it's operating the lock manually however it will open the boot.

Edited by gavinbailey on Tuesday 16th February 20:13

[M5 Russ]

When you buy your new battery, dont discount getting one from the BMW dealer. I got my new battery for the M5 from my local dealer as they were slightly cheaper than places like Halfrauds etc.

Also ask for a discount (saying you are self employed should net a 5% discount) plus being a member of the BMW Car Club gets a nice discount too

Edited by M5 Russ on Tuesday 16th February 22:34

[JerseyS2000]

Thanks for the replies, chaps.

I'm looking at an eBay solar trickle charger for £13 delivered. Sounds like a bargain as long as it will work through the window glass. I don't trust leaving it on the roof, for example.

I'll check out battery prices once I'm back from my holiday

Cheers

Ben

[JerseyS2000]

hmm back from holiday and the solar trickle charger worked well. But another problem has arisen that I could use some help with.

Before I left, I tried using one of the spare keys to unlock the car. The button didn't work so I just turned the key in the lock. The door opened but the alarm sounded. I fetched my usual key to silence the alarm and the car didn;t want to start first time. In fact, the dash was completely blank. After a minute or so, the car started but with a bleep on ignition.

Following the holiday, the car bleeped on ignition today and bleeped again whilst driving. Just as I was reversing into my parking space, the car died altogether and the dash is blank again. Turning the key in the ignition just makes it click but nothing else.

HELP!

Have I somehow kicked in the immobiliser? It shouldn;t be the battery since I bought a new one before I left. Any ideas how to fix this?

cheers (and sorry for the long post)

Ben

[MarkwG]

JerseyS2000 said:

Before I left, I tried using one of the spare keys to unlock the car. The button didn't work so I just turned the key in the lock. The door opened but the alarm sounded. I fetched my usual key to silence the alarm and the car didn;t want to start first time. In fact, the dash was completely blank. After a minute or so, the car started but with a bleep on ignition.

Following the holiday, the car bleeped on ignition today and bleeped again whilst driving. Just as I was reversing into my parking space, the car died altogether and the dash is blank again. Turning the key in the ignition just makes it click but nothing else. Ben

sounds like a mix of issues to me:
if the key button doesn't work, it's either knackered or needs charging. It charges through the ignition switch, so if you don't use it, it will die on you. It'll let you in, & let you start up, but the alarm triggers off the central locking circuit - hence the sounds. It recognises the key, once it's in the ignition & the fact that the car then started sounds good.
The blank dash & car death sounds like the main battery, or possibly the ignition switch. Even if it's a new one, the solar charger will only keep it going, running the tracker etc; it won't give it enough charge for lots of stop/starts. For that, you need a trickle charger.
You can either fork out for a battery test, or, try a start with the headlamps on - if they go really dim as the starter takes the load, I'd bet the battery needs charging. If it is the switch, that's a simple fix, anyway, 20 mins with a couple of simple tools.

[andy3781]

I changed my battery the other day on my m5, i got it from eurocarparts, £126 correct size and a 5 year guarantee.

[JerseyS2000]

some sound advice except i did buy a brand new battery for the car 4 weeks ago and it has been connected to a trickle charger

[MarkwG]

JerseyS2000 said:

some sound advice except i did buy a brand new battery for the car 4 weeks ago and it has been connected to a trickle charger

- if all the connections are tight, it sounds like the ignition switch then, although if you can get a diagnostic check done, that would eliminate anything else. It causes all sorts of weird symptoms. New ones are circa £40, & you'll need a small Torx head (from memory) to remove it. You can access it by removing the lower steering column shroud. Simple plug'n'play job, just a bit fiddly.

[JerseyS2000]

thanks Mark

I'l check the connections this weekend then speak to my friendly mechanic. the car is due for a service anyway.

cheers

Ben