4 replies to this topic

[maieth]

Hi folks, having some trouble with battery not holding charge on 2000reg CooperSport. Ongoing problem that I've put a fair bit of cash behind and I'm now completely baffled.


Basically I replaced a dead battery just before service and MOT last August, then during service, my mechanic put new terminals on battery leads as these were a bit damaged by a previous, unrelated problem. Still had problems with battery not holding charge so got alternator checked and garage decided it was fairly dead. Duly replaced alternator (Now October). All seemed well and I then garaged the car for the winter.
The battery was again completely flat a couple of weeks ago when I came to drag car out of hibernation (assumed this was just from not being run for 3 months) so I charged it from my daily driver last week and left it hooked up to a trickle charger from the mains. Today the battery is completely flat again. Not a pulse.
Thoughts?

Edited by maieth, 17 March 2012 - 12:23 PM.

[andymini12]

It is probaly were you have left the battery untoched over winter that seems to just kill them off even if it is a decent battery, i have had the same thing with my one when it was left over winter. Do you have a warranty on it? Alot of batterys come with a 3 year warranty now.

[maieth]

Got one, but no idea where it went

[Sprocket]

If you have left the battery connected with the car in storage, the radio and the alarm will soon drain the battery if the car is not used in two weeks. This is not a problem.

if however no matter what you do the battery still drains, you'll have to look at the relay pack and the ECU as if the ECU holds on the main relay for what ever reason, with the ignition off, it soon drains the battery.

The dim dip relay can also sometimes cause a permenant drain on the battery.

The other thing that can happen, is when a battery is deep discharged and left in an uncharged state, sulphation can occur and the battery will be near impossible to recover properly.

Edited by Sprocket, 17 March 2012 - 01:45 PM.

[maieth]

If you have left the battery connected with the car in storage, the radio and the alarm will soon drain the battery if the car is not used in two weeks. This is not a problem.

if however no matter what you do the battery still drains, you'll have to look at the relay pack and the ECU as if the ECU holds on the main relay for what ever reason, with the ignition off, it soon drains the battery.

The dim dip relay can also sometimes cause a permenant drain on the battery.

The other thing that can happen, is when a battery is deep discharged and left in an uncharged state, sulphation can occur and the battery will be near impossible to recover properly.

Thanks. I'll try and regularly check it over the next few days to see if it holds charge day-to-day. I guess checking the main relay and ECU would be a garage job? I'm really only set up to do pretty basic, mechanical jobs at home.