New Battery help - UPDATED with Pics as well.

[The Mighty Elvi]

Just taken delivery of my brand new 075 battery.

12.72 v out of the box.

With car at idle for about 5 minutes I get 13.98 v at the blue wire on the Alternator.

I put the revs up and held it for a minute and not getting an more volts into the battery. Stays around 12.7.

Lights and blower on and battery drops to 12.58.

Where might the problem be between Alternator and battery?

Or

is this a revs/time thing that will increase the v from the alternator to the battery at some time during driving.

Any help as I dont want to piss £48 down the drain.

Thanks

Jonathan.

_______________________________________________________________________________________________________________



UPDATE:

Just fitted the new voltage regulator:  Here are the scores on the doors.

Engine at idle for about 20 minutes during test.

12.78 v at battery with engine off.

13.47 v at battery with engine on.

14.38 v at Alternator with engine on.

_____________________________________________

Engine at idle for following tests:

13.45 v with the radio on.

13.26 v with only blowers on full.

13.04 v with blowers and lights on main beam

12.60 v with blowers, lights and radio on.  (13.76 at alternator, then fan kicks in and drops to 13.69)

_____________________________________________

All above switched off, engine at idle.

13.47 v at battery - fan kicks in and drops to 13.31 v.


Engine switched off.  End of test.

12.88 at battery.

Now, any answers as to why the voltage is dropping off when I turn things on.

As a note, both the Rev counter and the MFA are not working.

Pics below.  Could it be the flimsy earth strap between coil and manifold?? I know it's only there for safety just in case the coil goes, but is it worth uprgrading.  Or is it the earths from the battery - starter - gearbox - cables that need upgrading to a thicker guage?

Thanks.

1. New v old.



2. FUBAR'd.



3. Deep inside.



4. The alternator conections.



5. Starter motor.



6. POWER!!!!



7. IUD.



8. Strap on.

[rubjonny]

does the battery light come on with the ignition then go out once car started?

[The Mighty Elvi]

Yes.  It goes out.

All the earths are also clean.

[The Mighty Elvi]

Plus my rev counter isn't working.

[rubjonny]

if the light comes on then that means the blue wire is connected up ok, so that leaves a fault with the alternator or battery cabling. take all the alt, battery and starter wires off and clean them up. take the brush pack off the back and give it a clean up on the contact points, there is an earth ring round one of the screw holes and 2 metal contact pins inside the hole where it came out of. clean up the contact face on the brush pack that these touch. also make sure brushes are good.

when you say at the blue wire, are you testing this with the wire disconnected?

with the rev counter pull the dash fuse for 30 seconds then refit. if that doesnt help check the red/black wires at the coil

[The Mighty Elvi]

if the light comes on then that means the blue wire is connected up ok, so that leaves a fault with the alternator or battery cabling. take all the alt, battery and starter wires off and clean them up. take the brush pack off the back and give it a clean up on the contact points, there is an earth ring round one of the screw holes and 2 metal contact pins inside the hole where it came out of. clean up the contact face on the brush pack that these touch. also make sure brushes are good.

when you say at the blue wire, are you testing this with the wire disconnected?

with the rev counter pull the dash fuse for 30 seconds then refit. if that doesnt help check the red/black wires at the coil

Thanks John. I'll have a look in the morning.

I was testing the alternator at the blue wire nut/spade still connected to the alternator.

[clipperjay]

So what are you getting at the alternator direct?
I would have thought you should be getting at least over 14.3V right off the alternator?
Sounds like you could have a dodgy voltage regulator on the alternator itself?
 

[The Mighty Elvi]

So what are you getting at the alternator direct?
I would have thought you should be getting at least over 14.3V right off the alternator?
Sounds like you could have a dodgy voltage regulator on the alternator itself?
 

Perhaps my method is wrong?

Using a voltmeter I placed the red wire on the nut/spade of the small blue wire that is connected to the alternator.  I then earthed the black wire on the exhaust manifold.

I got a reading of around 13.9 volts.

[The Mighty Elvi]

Search tells me it may be a worn/faulty voltage regulator.

I'll take it off an look in the morning.

[clipperjay]

It might be worth trying to double up the earth terminal down to the gear box mount bolts I do this as a matter of course with any Mk2. Or you could upgrade all cables to a Corrado ones?
Take a look at my pictures on dub rides you can see the difference it makes when upgrading to thicker cables 
Half way down!
http://www.golfgtiforum.co.uk/index.php?topic=170521.10