205 Wont Start Without A 2nd Battery

[WooDooUK 1]

Here is a bit of a strange one for you all.

 

My recently put together 205 GTI 1.9 is now refusing to start after putting it back on the road.

 

The car will only start if it is jumped off another car or battery. Once started the Alternator is charging the battery @ 14.3 Volts.

Before trying to start the car the battery is reading 12.2Volts.

 

However unless the 2nd battery is connected the car just refuses to crank. (can hear the fuel pump)

 

Maybe related, maybe not but when the engine is running the battery light is dimly litup (does not change with engine revs) Could a faulty Alternator cause these sorts of issues?

Edited February 10, 2010 by WooDooUK

[pablo 0]

check the voltage when the light is dimming like that. But 14+ is good going for an alternator. If its putting that out all the time then the battery would have to be suspect.

 

Is the car running ok? I mean once jump started is it able to do a good run etc? If it is then the alternator is probably ok and the battery suspect.

[DrSarty 90 1 Cars]

You say it refuses to crank, but do we know if it's trying to?

 

Please just clarify: does the engine crank with a second battery attached?

 

What happens if you swap the batteries over?

 

I can only feel it's a battery fault (i.e. it breaks down in a cell when put under load), or you have a weak earth from the neg terminal to the gearbox and chassis.

 

Swap batteries first and see what gives.

[WooDooUK 1]

Yeap, The car runs fine once started.

 

 

You say it refuses to crank, but do we know if it's trying to?

 

Please just clarify: does the engine crank with a second battery attached?

Good point! i should have mentioned that, the starter is not even going clunk on the original battery/

 

I havent tried removing the original battery completley. (School boy error Should have done that first).

Cheers guys, i will let you know how i get on. Hope its not ther battery as its not that old. (then again it is an easy fix)

[pablo 0]

sounds like the battery aint charging but once started the alternator is able to run the car. Check the connections as sarty said and see if that helps.

 

Swapping in a good battery may seem to solve the problem at first as it will be fully charged, but if there is an alternator problem it will take a while for it to show until the battery runs flat. Doesnt sound like that though.

[DrSarty 90 1 Cars]

There's nothing wrong with his alternator; it's chucking out 14.3v.

[pablo 0]

the battery light being on even dimly is a bit suspect tho no?

[welshpug 1,657]

earthing issues can cause that, most likely to be the transmission to body earth.

 

Also a battery being down at 12.2v isn't quite sufficient, though I would expect it to be charged back up nearer 13 if the alternator is working fine as it seems to be.

[pablo 0]

Would a battery ever be 13v with the car not running? I thought around 12 was where it should be at.

[jackherer 543]

the battery light being on even dimly is a bit suspect tho no?

 

As the running voltage is sufficiently high it suggests a wiring or earth problem rather than a faulty alternator.

 

I had it on my pug for ages until one day the ring connector on the alternator thick cable completely snapped leaving me stranded. When I crimped a new ring connector on the dim battery light was gone for good.

[WooDooUK 1]

earthing issues can cause that, most likely to be the transmission to body earth.

 

Also a battery being down at 12.2v isn't quite sufficient, though I would expect it to be charged back up nearer 13 if the alternator is working fine as it seems to be.

 

 

On the earting point on the gearbox there is currently three wires. the large black one going to the -ve terminal on the battery, and 2 medium sized wires going into the engine loom.

I guess from the colour its these yellow/green wires are the earths for the engine loom. The earthing terminal on the box is clean. Could the problem be the other end of these two earth wires?

 

and just to note: from the other side of ther battery terminal is another wire going to the plate the Ignition amp is on

[large 33]

How are you connecting the jump leads to the car? If you are putting them to the battery terminals and the car is starting all the wiring on the car must be ok.

 

Has your bat been flat? If so the cells may have collapsed. This will show as the bat reading as charged 12.4v but the current output will be greatly reduced.

[pugdamo 111 2 Cars]

I know you have voltage there but is there current,i would say its a knackered battery,especially with all the cold weather lately.

As already said probably a dead cell in the battery

[WooDooUK 1]

Turns out that the battery is knacked after all. Amazed at how a battery can go in the blink of an eye.

 

should still be under warranty so that is a bonus. Just need to find the receipt now.