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Poor charging

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Hoping someone can give a little advice on this.

 

Not had my G60 all that long, and after a couple of weeks found the battery had died one night when leaving work. So i fitted a new battery, its a Varta Blue heavy duty one, and checked the charging system and found it to be working fine. Been using the car for the past few weeks no problems.

However tonight before leaving work i put my lights on for approx 5 mins without the engine running whilst changing a bulb, then when i went to start the battery had dropped to 10V so wouldn't crank the engine over. Jump started it and got it running and then checked the charging at the battery again and found now to only be charging at 13.4V. Switched the lights on and stereo etc and its charging at 13.2V and if i put all the lights on and wipers with the heater blower it only charges at 12.9-13V.

The heavens then decided to open so went inside til it stopped so i could do some more checks etc. Left the car for approx 30mins and the battery has already dropped to 10.4V and now won't start again! Obviously my first reaction is that the alternator is knackered, however not been able to check charging at the alternator yet, hoping to do so tomorrow to confirm my thoughts.

Guessing that as the battery isn't holding charge now, that where the alternator has only been trickle charging it for a little while now that it may have knackered it possibly? Going to test it tomorrow and put it on charge to see if it'll hold that.

 

The car does have an aftermarket immobiliser fitted and i've fitted my alpine headunit, which i've noticed when i insert the key into the ignition (without turning it) the stereo fires up, whereas my mk4 golf i had previously i had to put the ignition on to power up the stereo and would then only go off once the key was removed? Is this normal on corrado's?

 

Any help is appreciated as its doing my head in :scratch:

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Check the alternator brushes... On the back of the alternator theres two philips screws. Remove them and remove the brushes. Check the length of the brushes.

And check voltage at battery while holding the revs at 2000rpm.

Tell us the out come of that

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check the small wire attached to the alternater,think its a 8mm or 10mm nut as this is a important wire as it supplys 12v to the exciter coil in the alternater. without it you wont get a proper charge or no charge.

 

if the brushes are nearly worn out then you'll find the lights will all flicker constantly and flicker faster with engine revs

 

---------- Post added at 09:24 PM ---------- Previous post was at 09:15 PM ----------

 

sorry had a brain fart-brushed motors dont have exciter coils!! :roll:

 

The small wire puts the battery light out on the dash when charging.

 

Other than worn brushes/slip rings and corroded/loose cables there isnt any reason it shouldnt charge.I would suspect one of the items you've fitted is draining the baterry,prob imobilizer

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Right just been out and jump started it so as i can get some readings now.

 

Checked charging at the battery when idling and its 13.6V but slowly drops. When the revs are raised it goes up a lil bit but not a lot, then drops again once the revs are let off. Checked charging at the alternator and found it be charging at 14.04V, but does drop slowly. Also checked the little wire aswell and found thats got a permanent 14.05-14.1V, haven't checked the wire though, only the stud sticking out.

 

Took the brushes out aswell and measured one at approx 0.8-0.7mm and the other at approx 0.5-0.6mm

 

---------- Post added at 08:40 PM ---------- Previous post was at 08:36 PM ----------

 

Also did a drain check by taking the negative lead off with all the doors shut and everything off and found its only draining 0.015A, which can't really be enough to drain a battery can it?

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unfortunately volts check doesnt confirm how many amps the alternater is putting out.You need a ampmeter for that.

 

14v sounds a little high,maybe just because the battery is flat but dont rule out the voltage regulater

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Right just been out and jump started it so as i can get some readings now.

 

Checked charging at the battery when idling and its 13.6V but slowly drops. When the revs are raised it goes up a lil bit but not a lot, then drops again once the revs are let off. Checked charging at the alternator and found it be charging at 14.04V, but does drop slowly. Also checked the little wire aswell and found thats got a permanent 14.05-14.1V, haven't checked the wire though, only the stud sticking out.

 

Took the brushes out aswell and measured one at approx 0.8-0.7mm and the other at approx 0.5-0.6mm

 

---------- Post added at 08:40 PM ---------- Previous post was at 08:36 PM ----------

 

Also did a drain check by taking the negative lead off with all the doors shut and everything off and found its only draining 0.015A, which can't really be enough to drain a battery can it?

 

0.8mm thats low....

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unfortunately volts check doesnt confirm how many amps the alternater is putting out.You need a ampmeter for that.

 

14v sounds a little high,maybe just because the battery is flat but dont rule out the voltage regulater

 

How many amps should it put out roughly? my multimeter measures amps aswell so could do a check tomorrow, struggling with no light tonight :(

 

---------- Post added at 08:46 PM ---------- Previous post was at 08:45 PM ----------

 

0.8mm thats low....

 

What should they be? Wheres the best place to get new bushes from? Its a bosch unit

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wont try to test a car alternator with a small voltmeter/ampmeter,most only test 10 amp MAX for few seconds.Car ones have way more ampage and you'll blow it. check what amps the reader can test to.

 

---------- Post added at 09:52 PM ---------- Previous post was at 09:51 PM ----------

 

brushes are ok then

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wont try to test a car alternator with a small voltmeter/ampmeter,most only test 10 amp MAX for few seconds.Car ones have way more ampage and you'll blow it. check what amps the reader can test to.

 

Mine tests to 20A, so i'm guessing that won't be enough considering most alternators are 65A rating?

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yep,need one that will test to about 100 amp

 

---------- Post added at 09:58 PM ---------- Previous post was at 09:56 PM ----------

 

Out of curiousity,how old is that new battery?

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Crap! :scratch: i'll have to see if i can borrow one, never used one before lol.

 

The new battery is about 2-3 weeks old, going to battery test it tomorrow to make sure all the cells are ok.

 

What i can't work out is why at the alternator i was getting 14V approx which dropped a bit as the engine warmed up, but at the battery was alot lower and kept dropping? The big terminal on the back of the alternator did look a bit dirty so may clean that up to make sure its a good connection, same with the little wire aswell

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check the large red wire that goes to the starter then to the battery has good contact also

 

A discharged battery will cause the regulater to up the voltage which will drop as the battery is becoming charged but this should happen slowly.and voltage shouldnt drop below 13 volts uless theres a massive draw on the system

 

Best way to check the battery-charge it,check the voltage once you turn engine off,then leave it overnight unplugged.reconnect,then crank it for a few seconds to remove surface charge.unplug and test voltage again.anything under 10v your battery isnt holding its charge

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Yeah when i checked the charging earlier with everything on and found it was only charging at 12.9-13V then i knew there definitely was a problem, and it was still dropping then aswell.

I'll check that starter wire tomorrow then aswell and i'll also stick my battery on charge and test it aswell.

 

Appreciate the help

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Right well jumped started it this morning as it was flat again (neighbours love me) got myself to work no probs and switched off. Left it for 10mins max and had already dropped to 10.3V. So carried out a battery test and discovered that it has a bad cell, which isprobably why it won't take charge properly.

Going to get the battery changed and then recheck the charging system

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Glad you found problem mate,i never rule out a new part as cause of the problem because its happened to me before!!!

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Right made a bit more progress now. Put a spare battery on the car and it now starts ok and appears to hold charge (find out in the morning). However checked the charging system and something still isn't right.

Discovered that the main battery lead to the starter motor was loose, so tightened that up, and also found the main lead to the alternator appeared to be corroded on the connector, so cut it back and put a new end on and then retested it. Charging appears to be alot better now, but as soon as things are switched on, i.e lights, heater etc, the charging drops. This makes me think that the voltage stabiliser isn't working, to up the charge rate when more load is put on?

Checked the little wire going to the alternator, and with just the ignition on, I get 1.4V, then with the engine running i get 14.1V, whilst at the big lead on the alternator I get roughly 13.9V, and at the battery approx 13.8V. Is that right?

I have also run a separate earth from the head to the alternator in case it wasn't earthing properly but doesn't appear to have done anything

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