XSeries-forum

In fairness, the first time it happened I was going from the boot to inside quite a bit so that would have reset the 15 mins timer. But the second time that wouldn't have been the case.

Ok, so the on charge reading was fine and immediately after a charge of about 18 hours using the CTEK 7000 the voltage was 12.8 with no fault light lit on the charger so it could be ok or there could be another fault. I'll monitor it and see. As always, thanks for the help.

[quote=""X5Sport""]Be intersting to know what the terminal voltages are on the battery. It they're OK then there is another option. There have been a number of issues with the starter motor devloping an internal fault which means it draws more current that the battery can provide so the battery volts drop sharply and as a result either fails to start, or turns over too slowly and struggles to start. This often causes all the on board computers to reset

My starter was changed at just under 3 years. No fault ever showed up on the computer logs, or on the BMW diagnostic system. The fault was found by a tech using a current clamp and intuition working from first principles. It was more of a problem on cold days.[/quote]

I replaced my battery Nov '10 after this sorta prob , only to find I had the same problem occurring .
When I mentioned it to my Indy , he said to do a voltage drop test whilst starting as the starter was probably knackered (it's Magnetti Marelli not Bosch on these) .

I havn't got the right equipment for a drop test , so I told him to just change the Starter Motor anyway if that's what he suspected , which he did Dec '10 .
When I picked it up , he told me they did a test beforehand just to be sure , and that it went off the scale of their equipment , which was over 800A !!

Now I have absolutely no probs at all .

It's in at the dealers at them moment and apparently they've charged run some tests including charging it then leaving it for a bit etc etc and it's ok. To find out if there's another problem would require further diagnostics so I'll see if it is ok in normal use and take it from there. I have a voltmeter so if someone can exlain how to (safely) test voltage drop on startup and what to set the meter to then I could give that a go.

As most of us do not have the right kit, the only way you can do a volt drop test is directly on the battery terminals. You only need it on a 20V DC range. Crank the engine and see what the volts drop to. If you have access to a current clamp capable of handling 1,000Amps then you can do it yourself.

I think the garages will be using a device called a DC Current Clamp, which in simple terms is a wire coil in a cylinder form that can read the current flowing in the wire (Boring theory bit - a current flowing in a wire generates a magnetic field and a coil of wire placed in a magnetic field generates a voltage) and gives a read out.

If I remember correctly my own starter motor was pulling over 800A too and was changed. This fault does not generate any errors on the BMW diagnostic system, it can only be found by use of the right test equipment. It took 2 dealers no less than 6 attempts to find it, and only on the last attempt did the Technician not use the diagnostics and used a proper battery testing system which found the issue immediately. Good thing it was a warranty job or I would have been hopping mad. As an engineer I had been asking them what the battery load tests showed and what the starter draw was. They just looked blank at me and deeper questioning found the BMW diagnostic hardware simply could not find this fault as the capability did not exist. Keep pushing them to do a first principles old fashioned proper battery drop test when the starter is engaged.

[quote=""pvr""]Not sure if I understand the door open / boot open scenario. When I wax the car, doors and boot etc are open but after about 15 minutes, the lights all go off by themselves.

The only way they stay on is if you open / close in the meantime, as the 15 minutes is reset then. That is why I just leave the lot open for the afternoon that I am working on it.[/quote]

Did I not read on here somewhere that if you press and hold the interior light button for 10 seconds it switches the interiors off off????

Please feel free to ignore if I'm talking outa my ar@e

Just a thought though


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Just to check my understanding. I can check the voltage drop safely but would have to do this on start up with the voltmeter connected to the battery terminals (not the under bonnet termninals)? or, if 800A is going to go through it then presumably I can't and it would be dangerous to try or is this something else?

Do you mean that your starter motor was drawing 800A and that is far too much thereby draining the battery on start up?

[quote=""Dan1502""]Just to check my understanding. I can check the voltage drop safely but would have to do this on start up with the voltmeter connected to the battery terminals (not the under bonnet termninals)? or, if 800A is going to go through it then presumably I can't and it would be dangerous to try or is this something else?

Do you mean that your starter motor was drawing 800A and that is far too much thereby draining the battery on start up?[/quote]

No, if you connect your meter to the under bonnet terminals and set for voltage, as you start the car the voltage reading will drop by a volt or two. If the starter is drawing excessive current (800A for example) the battery wouldn't be able to cope and so the voltage reading would drop by a much higher amount, possibly half.

This is all perfectly safe to do as long as you keep your meter and leads clear of any moving parts and the meter can't fall.

HTH


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The battery has been ok since so haven't tested with a meter yet.

Hi Folks,
Just thought i would add a bit to this to see if any more info comes out of it, end of last week my bty went dead after my X5 was sitting for 4 days without starting it, only thing i did was go into the boot a few times over that period. Tried to start it on the 4th day but could not even open the doors with the remote.

Called the RAC as i was stranded at work, he came out and eventually got it going after about 15 mins of a jump start, he did a amp check straight from the bty with a meter while he was sitting inside it with car locked down and it was still drawing 0.9 amps, he said with the car locked it should draw no more than 0.3 amps, so he said something is staying live after i lock the car. Only thing we could see was a little orange light on the gear box stays on while in the park position.
(anybody else get this???).

He aslo checked the bty and says it was good.

He disconnected the light from under the console and amps fell to 0.6amps but reckons still too high and say this would kill the bty after 4 days and could not find anything else?

It is booked into a Diasnostic centre in Licoln for futher checks this week (recommended by the RAC), he says if they cant find the problem nodody can!!!!!!.

I will post if any problems found or if anybody else has any ideas please post.

Thanks.

I'd change the FSR ( final stage resistor) there are 'how to's for this on this forum.
Lez

Hi, my car has the same 0.9A drain. It was the Main engine coolong fan causing the problem. Because i use tha car every day i havent bothered getting it fixed yet. (fuse 60 or 61 -50A in the glove box.)

Found this out with the multimeter in current mode, placed in series on the negative lead. I then let the car go to sleep and removed fuses 1 by 1 until the current dropped below 0.20A. Dont put fuses back in until finished or it will wake the car up and you will have to wait another 30 minute for it to go to sleep again.

IIRC the orange light on the gear selector is normal until the car goes to sleep.

PeterT

Thanks for the info guys, I'll post when i have this fixed or my findings.

Cheers.

I would put a current meter on the red lead, jump point under the bonnet try start the car and get some to see what the current draw is on the meter, should be180 to 300 amps mine was inexcess of 600 amps.............new starter.
Hope this helps