4 replies to this topic

[karen11uk]

Hi

if anyone can give me some pointers on this one i will be very grateful as its driving me nuts now !! and need a list of suggestions or ideas where to start ????????

bought my mini 2 weeks later had to fit a new battery as i was led to believe that the one that was in my car was knackered !!

now after not using my car for a week it won't start so have tried using jump leads and it starts ok i take it out for a drive, when you go to start it the next day it refuses to start and so on and so on !!

we have checked the battery and that seems ok, the alternator seems ok too so if anyone has any other ideas where to check next as it seems to be turning into a process of elimination to find this fault.

i have a 1999 cooper which does have an emobiliser which does seem to be very tempramental so i do wonder if this is the cause.

any help many thanks

karen and cooper
x

[bourney]

Start the car and put a voltmeter (multi meter) across your battery terminals. With the car running the multi-meter should be reading around 14v. If it does then your alternator is ok.
Next i would check for a drain on the battery. Set the multi-meter to amps. remove the positive lead from the battery terminal. Now put your multi-meter between the positive terminal and the positive lead. Bear in mind with the immobiliser/alarm it will have a slight draw on the battery, clocks etc also have a draw, but nothing big enough to kill the battery overnight.

I've normally found that the draw would be an incorrectly wired amp thats staying on, or boot light or something similar is staying lit.


Bit of a long shot i think but you could always check your earths. A bad earth will mean you'll need to push more amperage to the starter just to get over the high resistance of the bad earth.
To check your earths set the multi meter to ohms and put the multi meter between the earth point and the negative terminal of the battery, you should have pretty much 0 resistance. I wouldn't bother with that though, i'd just clean the earths anyway, might aswell, it can only do good

[Ethel]

I wouldn't expect an immobiliser to be able to run a battery flat overnight. You could detach a battery lead when you park up to eliminate anything running the battery flat, as a test. You'd have to reset the immobiliser of course.

Multimeters measure resistance using their own, internal battery (so they have a known & accurate voltage). It would be best to disconnect the battery for the test - or you could measure the voltage drop when it's cranking the engine instead.

[karen11uk]

Thank you so much for your suggestions, i wil certainely give it all a try !!

karen and cooper

[bmcecosse]

Make sure the fan belt is tight enough to run the alternator properly.