Is My Alternator Knackered?

[Guest Mat_C]

Friday night a mate and myself were taking part in a "Navigational Scatter" (Essentially a sort of road rally).

As we were driving, we had gone for probably an hour tops when all the lights started getting dim, I noticed it first when my potti became almost useless.

The headlights were getting dimmer, as were the dashboard illumination, the rev counter stopped working and the engine stated coughing and spluttering.

Eventually the car completely died, dead as a doornail, won't turn over or anything, just a faint glow from the dashboard ignition lights.

So get the car back to the pub (Don't ask), and dump it in the car park over night.

This is where it gets confusing. In the morning we bump started the car (started first bump) and ran it 10 miles or so. When it came to restart the engine, the battery was dead, so bumped it and it started fine. So in that case dead battery, yes? The car seems to be working fine off the alternator and the battery is not holding charge.

However..... later on after bumping the car it died again, no electricity anywhere in the car, the battery was flat again, so put the multimeter on the battery and checked it. 12volts with nothing on, switched the lights on, down to 5 volts.

So, charged the battery and off she went. Now we have a "Master Switch" which kills the connection to the battery. It's not been wired in correctly, so if you turn it off when the engines running the engine continues to run, I've always assumed it's because the alternator keeps the enging running. However now it just kills the engine, leaving me to assume the alternator's gone.

The multimeter seems to back this up, with a reading of 12volts at tickover and 12.5 at around 3000 rpm.

So this leads me to think the alternators had it. It's just the running with a flat battery earlier on that has me confused.

I should add that during the "rally" we had the spotlights on (Cibie Oscars) which I think may have completely drained the battery and wiped out the alternator as the current drawn was too much.

 

Anyone come across something like this before?

 

Oh, the car is a 1.4 XS TU Engine.

 

Any advice etc warmly welcomed

 

Cheers

 

Mat

[christopher 5 1 Cars]

If I remember rightly I think you should be seeing 13 or 13.5 volts on tickover

[Mikey S 29 1 Cars]

it should be charging at around 13.8 to 14.2 volts. it sounds like the alternator cant give what your demanding from it. they are only a low ampege (SP?), around 50 amps iirc. it may be worth having a hunt around for an stronger alternator, 90 amp or so.

also try using a 205 diesel battery, there about double the power of a standard tu one.

Edited August 14, 2007 by pugger

[Guest Mat_C]

Thanks guys.

I've been looking around at uprated alternators and can get a 100 amp one for £120 which I think should do (I hope)

Like the idea of the diesel battery, sounds like a plan as it should fit in the exsisting battery tray I assume?

 

Its amazing how far you can drive on battery alone though, I managed over 100 miles and could still start the car a day later, though I didnt have lights, wipers, stereo on which would have helped...

 

 

Cheers

 

Mat