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vl battery or alternator issue?

johnni

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hey guys,

i went to start my berlina turbo to move it out of the way but when i turned the key to the ignition, i could hear the fuel pump but when it primed was really weak then the car wouldnt start.
I got my other car and hooked up the jumper cables and it started like normal but when i removed one jumper cable the vl stopped.

my volt gauge is not reading anything, just sits on 8 volts so thats telling me my battery is drained so could my battery be stuffed or my alternator or both? as im not sure why the vl stopped once i disconnected one jumper cable

thanks
 

vc commodore

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Best to jump the car and get it running and whilst it's running, use a multimetre on the alternator to see if it is putting out around 14 volts.

It is quite possible both battery and alternator are gone, but by starting at the alternator voltage, it will give you a starting point to work from.

Personally I think the alternator is the problem, considering it stops once the jumper lead is disconnected, by worth checking with a multimetre first
 

johnni

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how will i be able to test it from the alternator? straight from the back of the alternator?
 

krusing

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how will i be able to test it from the alternator? straight from the back of the alternator?
You can just test it at the Battery [on the Battery Posts], it should be 13.8 > 14.4 volts when idling to giving it a rev.
If you turn the headlights on it should drop to say roughly 14.2 volts
 

_R_J_K_

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I got my other car and hooked up the jumper cables and it started like normal but when i removed one jumper cable the vl stopped.
Should still test your battery still but this is a pretty good indicator it's the alternator.
 

vc commodore

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how will i be able to test it from the alternator? straight from the back of the alternator?
Yep...Should be the nut on the back of the alternator.

Personally I wouldn't test the alternator at the battery, if you have jumper leads connected.....Good chance you'll get a false reading, as the voltage from the secondary battery will be coming through the jumper leads.....

Once you have a good battery installed in the car, by all means test the voltage at the battery. However make sure you have 14 volts at the alternator before checking the battery voltage......If you don't have the 14 volts at the alternator, you won't get that at the battery
 

johnni

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i went ahead and bought a new battery today a optima red top 34 and the car started so much easier.

I tested it at the battery and was only getting approx 11.5 volts and my volt gauge in the car was reading about the same as well so time to buy a new alternator it appears
 

vc commodore

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i went ahead and bought a new battery today a optima red top 34 and the car started so much easier.

I tested it at the battery and was only getting approx 11.5 volts and my volt gauge in the car was reading about the same as well so time to buy a new alternator it appears

Sure is
 
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