Alternator not charging at idle

[airarms125]

Hi guys,

I drive a Kia Ceed 2.0 crdi and a few weeks back when the weather got really cold my car wouldn't start, battery didnt have enough power to turn the engine over.

I have charged the battery and all has been fine since, however this got me thinking as to what caused it? the battery was purchased new 6 months ago and is a cheapo "Lion" make from ECP but still should be ok for the car.

I have noticed that sometimes when on tickover the battery light comes on the dash but only very dim, if I didn't tell you it was there you'd never see it, this light does light up fine when turning ignition on so not just a dim bulb. I have measure the voltage at the battery before starting the car 12.1 which is low then when the car is idling it didn't go up at all and stayed at 12.1 when revving the car to 2000rpm the voltage did rise to 14.3v.

Im just wondering if anybody had an idea of what could be causing this? could it be a bad earth? A faulty battery? or a faulty alternator is more likely? If it is the alternator any ideas which part inside it could be, I wouldn't mind trying to refurbish it myself if possible. in my head I think the alternator is the most likely cause

the car is running fine now, I guess once im moving and not stuck in traffic it will get the correct charge, but I know this is not ideal and soon enough I will end up with a flat battery again.

[jeremyh1]

I would say the alternator is not charging right

[GreenV8S]

airarms125 said:

a few weeks back when the weather got really cold

It could be a duff battery, or your driving patterns not giving enough charging time to keep the battery charged, or a fault in the charging system, or some residual drain which is running the battery down while it is parked. The problem might have been building gradually and only become apparent when the battery was asked to start an engine in very cold conditions.

Has the behaviour of the no-charge warning lamp changed prior to this flat battery incident? Has anything else changed recently?

[airarms125]

yea see id consider anything being wrong with it, but just thinking that as the light on the dash only shows very dim and only when on tickover that its going to be a fault with the charging system, this was backed up by taking a reading on the battery with a multi meter.

Im just wondering if it could be a bad earth?

I do 8.5 miles to work and 8.5 back every day, never had a problem with any other cars ive had, even when doing 4 miles each way. just wondering if anybody had the same symptoms as me and what fixed it? presuming if its not a bad earth then it must be alternator but just wanted to see if there was a common fault on alternators that caused these symptoms?

[GreenV8S]

GreenV8S said:

Has the behaviour of the no-charge warning lamp changed prior to this flat battery incident? Has anything else changed recently?

[MB140]

I had this many years ago on a RS turbo. Turned out the belt was loose and slipping (but never made any noise at low revs but higher up the revs it was turning the alternator enough to turn the light out. Belt retensioned and problem solved.

[airarms125]

GreenV8S said:

Sorry, nothing has changed recently, driving habits had not changed at all.

Ive had a quick look at the belt and it feels tight enough, by feeling with my hand anyway, whats the proper way to check tension on a belt?