E39 M5 wont start after flat battery

[Ecosse79]

Hi all. I wondered if anyone could assist me with the following. My E39 M5 recently had a flat battery which I tried to jump start with my jump pack. This didn't work and the starter motor was just clicking, so I charged the car battery up to a healthy 12.9 volts. When I went to crank the car for the first time the engine started for about 2 seconds and then shut down. It now wont start and is just turning over on the starter motor. I have checked all of the fuses in the glove compartment and in the boot and they all look to be ok. I have also listened to the fuel pumps with the ignition on and they seem to be making all the correct noises. I am hoping I have not blown anything when jump starting and certainly hoping its not the ECU! Has anyone got any ideas? Many thanks

[rfsteel]

How did you connect the jump leads, directly to the battery terminals or via the jumping terminals in the engine bay ?

Not an S62 engine, but these are the jumping terminals;

Edited by rfsteel on Friday 3rd February 13:37

[Ecosse79]

I connected my jump pack initially to the engine terminals and then after no luck I connected them directly to the battery. I don't think my jump pack had enough juice to start the car so I charged the battery fully to around 12.9v. The car now just turns over on the starter motor but wont actually start. I am wondering if I have blown something somewhere in the electrical system or the immobiliser isn't allowing the engine to start..

[tjlazer]

You need a heck of a lot of juice to jump the m5. If using an ordinary car you'll have to run it for 20 mins or so before it has enough to fire up. I had a long running drain issue and this became quite familiar. The AA man always had to use the van power to get it going, the charger packs and standard leads won't cut it. Trust me the car will be fine you just need MORE POWER!!

[AndStilliRise]

tjlazer said:

You need a heck of a lot of juice to jump the m5. If using an ordinary car you'll have to run it for 20 mins or so before it has enough to fire up. I had a long running drain issue and this became quite familiar. The AA man always had to use the van power to get it going, the charger packs and standard leads won't cut it. Trust me the car will be fine you just need MORE POWER!!

Yep. This. You need POWER!!

Make sure you have good HD Duty cable's and let the donor car run for a few minutes. Other than that you have enough petrol right?

[chris116]

tjlazer said:

You need a heck of a lot of juice to jump the m5. If using an ordinary car you'll have to run it for 20 mins or so before it has enough to fire up. I had a long running drain issue and this became quite familiar. The AA man always had to use the van power to get it going, the charger packs and standard leads won't cut it. Trust me the car will be fine you just need MORE POWER!!

It's still a bugger to jump start! Breakdown guy must have spent over an hour last year trying to do it, ended up charging the battery from the van then jumping it.

[Welshbeef]

Sounds like the battery has had it so simply get a nice new Bosch silver 5 years hassle free.

[rfsteel]

AndStilliRise said:

Yep. This. You need POWER!!

You sure do

[TheAngryDog]

needs 13.5v in the battery iirc.

[Welshbeef]

Why doesn't Op just buy a new battery and be done with it?

[ds666]

Quite - I never understand why people solder on with poor batteries - still at least they can start next topics related to various electrical problems for the next few months ...

[TheAngryDog]

this is what I have done. By battery went flat. New one bought.

[warsteiner///M3]

has the ews jumped out of alignment..?
can sometimes happen with a very very weak battery, as one module can rollover to the next code but another module doesn't have enough juice..

[AndStilliRise]

TheAngryDog said:

this is what I have done. By battery went flat. New one bought.

Maybe, like me, the M5 does not get used a great deal, living in London. I tend to use mine every 2 or 3 weeks on a weekend, so the battery does frequently run down

[ds666]

[quote=warsteiner///M3]has the ews jumped out of alignment..?

See what I mean - there is a crowdfunding page for m5 batteries - google it

[Elliot2000]

This - probably just needs resetting on a laptop and I'll be away

warsteiner///M3 said:

has the ews jumped out of alignment..?
can sometimes happen with a very very weak battery, as one module can rollover to the next code but another module doesn't have enough juice..

[TheAngryDog]

AndStilliRise said:

TheAngryDog said:

this is what I have done. By battery went flat. New one bought.

Maybe, like me, the M5 does not get used a great deal, living in London. I tend to use mine every 2 or 3 weeks on a weekend, so the battery does frequently run down

mine hasn't been used since September

[Ecosse79]

I will put a new battery in if thats required but my smart charger says the battery is 100% ok. Will try another battery and go from there...

[warsteiner///M3]

might be an idea to get the fault codes read too

[nw942]

Ecosse79 said:

I will put a new battery in if thats required but my smart charger says the battery is 100% ok. Will try another battery and go from there...

If the battery is heavily sulphated the charger will say it's fully charged, but it won't actually be able to deliver the current you need when starting the car. The giveaway is that the charger is very quick to say that it is fully charged when you first try and charge it.