Hi peeps!
My girlfriends Seicento Sporting keeps getting a flat battery and as she hardly uses the car I'm not really surprised because she only drives it about a mile to work and back 2 or 3 times a week.
I'm thinking the alternator is faulty as the battery light is permanently on but it must be giving some charge as it doesn't go flat on a long drive.
Is there anything else could cause this other than a bad alternator?
I've never known a battery light to come on if it's just a bad battery? It would usually just fail to start but without any lights on the dash surely?

Thanks for your help,

Chris.

You are correct in that it wont be becasue of a flat or knackered battery. The batterly light indicatesa fault in the charging system. Check the output of the alternator with a multimeter, it could just be worn brushes meaning that it is providing a high enough output to properly charge the battery. Also check the belt for tightness to check it isnt slipping.

Good luck,
Alan

...oh and BTW when checking the output of the alternator, you are looking for about 14.4v!

a1ant said:

...oh and BTW when checking the output of the alternator, you are looking for about 14.4v!

Click to expand...

I'd prefer to see 13.8V, but as long as its more than 13 and less then 16 you should be OK.

Cheers

D

on the alternator check that little wire is connected, spade plug on it.

Thanks I'll check it out at the weekend

Thought I'd post an update on this.
I checked the battery and it was definately dead so I replaced it.
I'd checked the voltage from the alternator and it was good (14v ish) so tried disconnecting the battery with the car running and it didn't stall even with all the lights on so the alternator must be good.
However... the alternator light was still lit on the dash!
I went under the car and disconnected the small red wire from the alternator - the light went off - connected it back and the light came on again!
Surely that's operating the wrong way round???
I'm assuming the circuit that works the dash light is faulty.

The car has been running great with the new battery for a few weeks now but the dash light is annoying.
Any ideas?

Chris.

The wee wire supplies 12V to the alternator. Once the alternator is charging it should extinguish. I presume it goes on when the ignition is first switched on.

Cheers

D

rallycinq said:

I presume it goes on when the ignition is first switched on.

Cheers

D

Click to expand...

If everything is the way rallycinq says replace the voltage regulator.

Here's a picture for you

Click to enlarge

E50 is the cluster with the bulb in. The ignition barrel INT supplies battery voltage.

A10 is the alternator, where B+ is your big fat wire. D+ goes to the bulb.

If there is an alternator fault, D+ will be to ground, an cause the bulb to illuminate. This also happens when alternator isn't producing charge, ie. before you turn over the engine.

It if its producing a low voltage, ie. 6v, the bulb will start to illuminate very dim.

Any use to ya?

Kristian

That's really helpful

Is the voltage regulator you're talking about the one that's part of the alternator? and is it replaceable on it's own or is it a new alternator?

I'll get my multimeter out and investigate.
The light does seem to be dimmer than I'd expect but never changes intensity.
I'll check if it comes on immediately before the engine starts - I'm fairly sure it does.
Probably won't get chance to check this weekend as the weather is looking terrible!

Thanks peeps! :worship:

Thinking about it from the symptoms it's got to be the regulator that's faulty...

The other thing that might make sense is that if she leaves the front on the stereo over night the battery used to go flat straight away.
She always told me the head unit was faulty but maybe its draining the battery through some faulty circuit???