Da Booga

Got a problem with the electric circuit on my cossie, can anyone offer any advice? Bear in mind i'm a complete novice when it comes to car electrics though

I noticed the other day whilst sat at some traffic lights that the battery light came on faintly and would alter in brightness until I revved the engine to >3k revs. It's done it several times now, each time when the engine revs are quite low, either sat in traffic or cruising with the revs <3k. It's not a constant thing and only did it occasionally.

Yesterday whilst driving back from a clients I got caught in a heavy rain storm so had to have the wipers and lights on. I noticed the battery light was on more or less all of the time the engine was <3k revs but went off above 3k. After a while of driving (with the revs above 3k, so no battery light) I noticed the wipers gradually getting slower and slower and the headlights dimmer. I managed to get home but today when starting her up to try and locate the fault I let it idle for a while but as soon as the fans kicked in the engine stuttered and cut out & it wouldn't start without a jump start.

I have a voltage and amp meter testing kit but don't know where I should connect the clips and what voltage/amps to look for

I connected the voltmeter between the battery terminals with the engine off and it showed 10v but the car wouldn't even try and turn over, it barely had enough power to prime the fuel pump. With the engine running (after a jump start) the voltmeter showed 13volts between the terminals but would die after a minute or so of running without the jump leads connected.

I'm starting to think the problem may be with the battery but as I stated above car electrics aren't my strongest point so can anyone offer any further advice, or readings I could take to help, with the volt & amp meters.

Thanks in advance,

Gareth

Toe Knee

iTrader: (2)

think it should show about 13-14 volts when charging and be on about 12 when the cars not running, so sounds like the alternator is giving out a charge but the battery isnt holding properly as u have said!

Cos500

My 500 does the same sort of thing, had the new battery checked and its fine, had the alternator checked and thats fine, ive checked all the earths and anything else i could think of and just put it down to the immobiliser, seems allright at the moment but the battery light still comes on faint below about 2000 revs.

Da Booga

OK, i've put a new battery on and the battery light still comes on, although not nearly as much as before. I've got an alternator coming tomorrow so will swap that.

I've been told it's the voltage regulator by a mechanic. I know I could check the bushes etc. on the alternator but I need it spot on for Saturday morning so i'll put a new alternator on & pop some new bushes in the old one, if that's all it needs, then i'll just have to sell it on here

Thanks for the help anyways

Gareth

discodenkelly

Just done this on our lass's new car. It was her alternator that was at fault. A quick check to find out for sure is to start your car then disconnect the negative lead to the battery. If the car still runs the alternator is fine, if not you needs a new one.

3drstretch

iTrader: (1)

Your alternator is either on its way out or fooked mate.You had 13 volts when jump starting as it was picking up the other car's charge.Your light comes on under 3k rev's because it is under the fast idle switch in alternator which reduces voltage going to battery.Above 3k revs you were bringing the fast idle in and it charging a bit better but not enough to charge battery when you had lights/wipers on etc.Thats why it was on then.Change/recondition alternator and everything will be OK.And DO IT SOON otherwise you will fook up the battery you just bought as well.It is running fine at the minute as you are using the power in battery NOT what the alternator is chucking out.REMEMBER the battery is a storage of charge for the starting first thing the alternator more or less does the rest.

Think of this.When you First start car in morning it will take about 20 mins of driving to replenish the power you used starting car.If your alternator aint working your just killing the battery.

HTH

Da Booga

All changed and 100% OK now chaps Sold this morning now too