Cooper not starting, flat battery? READ ON

[colinthecooper]

Now this, has got me totally confused

My Mini Cooper (MY02) has had starting problems for yonks. I've checked everything (I can) but nothing makes sense.

I assume something is draining the power and of course in winter, it gets so bad that I get ~1-2 days before the dreaded "click" as nothing happens when I turn the key.

However... the puzzle gets worse.

This morning (-1 degree c) I go outside to try out the Mini. It has not been used in about 36hrs. "Click".. then click click click (not even turning the engine over. This is normal.

So, I reach for the (now very handy) charger and then off we go. One minute later (not more), and out of total curiosity, I pull off the charger, walk to the car and "VROOM" - instant fire up.

Clearly, it's not the battery !
The connections to the battery are well made and tight
Battery <18months old

I'm thinking of starter solenoid, brushes. I have to rule out connections... (or it would have stayed broken !)

THOUGHTS WELCOME !

Rgds

Steve

[goonerij]

If you have checked all of the routine things related to the battery, I am thinking it may be related to the immobilser .... (?). I recall having issues with our R53 S with it not starting, only to discover the immoboiliser was engaging .... can't remember how we solved it though , only that it was pretty basic ....

[MrLoz]

Hand you tested the battery charge whilst the engine is running with a multimeter? Is the battery definitely draining or drained? I wonder if the problem is with the starter motor or the solenoid that engages and disengages the starter motor. If you have a multimeter you could check for current drain with everything switched off and keys out if the ignition. Modern cars should automatically go into a kind of power hibernate mode where literally only the anti theft system and various computer systems draw a small current to keep memory alive and anti theft system operating.


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[Restyle]

Quote: Originally Posted by colinthecooper (original)

....Clearly, it's not the battery ! - Battery <18months old

Battery could still be faulty with a duff cell that brings voltage down - although batteries usually good for at least 4 years, small % will still fail in far less time

Quote:

I'm thinking of starter solenoid, brushes.

Nah - Think you can safely rule Starter out. - If faulty it just wouldnt start nomatter what voltage applied, but as it does after charging battery, then its almost certainly fine.
If it isnt the battery, then as has been already said - something is causing current drain with ignition off. Easiest way of checking is by putting Ammeter to measure current between a removed battery terminal & the connector (just dont try to start car when doing this else you'll blow the meter)
Make sure all doors & hatch are shut with you inside & ignition off for around 5 mins before making tests - then with meter dangling over back seat or similar, lets assume you see a current reading on meter of more than 1/2 (half) an Amp - which it shouldnt under normal conditions.
Now start removing fuses, & notice if current drain dissappears when a particular one removed - problem narrowed down.
Or it could be something not covered by fuses such as the regulator gone on the alternator which could also cause similar drain.
If you've not got a meter, then if buying get one that can read around 10 amps - the very cheap ones may only go up to 0.2 amp.
Maplin Meter Link