Seat Leon 1.4 Battery/Alternator Question

[agentz]

Hi everyone

We've got a Y-plate Leon 1.4S with 73k miles on it and as you'd expect for a car of it's age it's starting to need wee bits and pieces done to it. The car has had very little use over the last four and a half months as my partner has been working away from home. I've been trying to take it out for a run about once a week but then we had all that snow before Christmas so that kinda knocked it on the head for a few weeks.

After the snow had shifted and I was able to get to the car again I was quite dubious that it'd start, but it did, first turn of the key and only a few seconds of turning over. Excellent. Took it out for about a 15 mile run and all seemed well. Then we had more snow and temperatures below -10 so it sat for another couple of weeks. I went out and started it, and again it started fine but the battery warning light stayed on but it seemed to be running fine.

Put my multimeter across the battery and was getting 14.1V at idle, rising to approx 14.4V if I took the revs up to about 2k, so it seemed like the alternator was doing it's thing. Took it out for a wee run, battery light stayed on the whole time, checked it with the meter again, still getting 14.1V at idle, switched it off and the battery seemed to be holding a charge OK, down to about 12.5V after an hour or so. Started no problem but the battery light still on. I did notice a slight noise coming from the general area of the alternator, almost like a very faint rubbing noise.

Connected up the battery charger just to see what it did, and it charged for about five minutes then went in to maintenance mode. Left it like that for a couple of hours, battery seemed healthy enough.

Started the car last week, and it started but it seemed to be 'surging' a little, battery light still on, but I noticed the dash illumination dipping a little - metered across the battery and it was fluctuating between 12.4V and 14.1V every second or so. Sat like this for about five minutes then settled down to a steady 14.1V at idle. Let it warm through, took it out for a spin round the block, about three miles, let it sit for half an hour, started it again and the same behaviour - voltage at the battery fluctuating again for a few minutes then steadied down.

Went out to start the car yesterday and dead as a very dead thing, meter across the battery gave me 7.5V. OK, so the battery has died over the last couple of weeks. Stuck the charger on it just out of hope more than anything else, charged for about 5 minutes, got the voltage up to about 12V then the charger declared defective battery and shut off.

OK, so now I've waffled too much to get to the actual question... about to go to Euro Car Parts to get a replacement battery, but do you think the alternator is also bust? Does the fact that a couple of weeks ago I was getting fluctuating voltage at the battery indicate that there's something up with the alternator, or could it simply have been a warning that the battery was about to die?

We bought the car about 5 years ago and in the handbook wallet was a pile of receipts from the old guy who owned it from new, and amongst them was a receipt for a replacement battery and alternator at about 42k miles, if my memory is working. So the battery and alternator are both about six years old (it's a big Bosch battery). There will be a new battery in the car later today, and I'll see how it behaves, see if the battery light stays on, but am I going to have to fork out about £180 for a replacement alternator from ECP as well?

[Tech1e]

I'd put a battery on first then check the charge rate again at the alternator. Might be worth checking the far left fuse on top of the battery with the big black cable going to it, check there are no signs of it melting.

Edited 22 January, 2011 by Tech1e

[agentz]

Thanks Tech1e

My next door neighbour helped out with a spare battery he had, which saw minimal use in his last car and is regularly charged. Connected it up to the Leon, got it started but it was doing the surging thing again, meter alternating between 11.9V and 13.7V. Only ran it for 30 seconds or so and it took a fair whack out of his battery. He's very good with auto electrics, has a lot of experience. Reckons one of the windings on the alternator is shorting, causing the battery to drain, which has killed the Bosch battery fitted in the car.

So, looks like I'm after a replacement battery and alternator. Was wondering how to get the car to the garage I've been using recently, which is about seven miles away. Checked and found that I've got RAC Option 3, which includes the 'at home' option so reckon the best bet is to call the RAC and get them to get the car to the garage some time next week.

Thanks again for your help.