Failing alternator and now a flat battery!

[Scribbler.]

I had this late one night driving 10 miles home. Needless to say I didn't make it home. Lights were required and wipers so ... However after having the alternator replaced at far less than the £260 and battery charged all inclusive for around £170, it has been fine since. I hasten to add my recovery delivered the car to my garage and me back home. Mike.

[neilbaker86]

Originally Posted by HarryM1BYT

The alternator connects directly across the battery, no fuses, just direct wire.

There is actually a fuse, it's Link 1 (150A) in the engine compartment fusebox.

[HarryM1BYT]

Originally Posted by neilbaker86

There is actually a fuse, it's Link 1 (150A) in the engine compartment fusebox.

Thats unusual. So pulling that fuse would isolate the alternator from the rest of the system and the battery, thus preventing the alternator discharging the battery assuming it might be doing that?

[SD1too]

Originally Posted by HarryM1BYT

Thats unusual. So pulling that fuse would isolate the alternator from the rest of the system and the battery ...?

It is indeed unusual. Checking the MGR wiring diagram shows that only the petrol engines have this fusible link (the diesel appears to be conventional). Removing it may have unpredictable results such as disabling the starter motor and possibly other functions since some other fuses appear to be fed via the alternator.

I wouldn't advise that anyone removes this fusible link and attempts to start the engine since an alternator shouldn't be run with its output open circuit.

Simon.

[COLVERT]

Originally Posted by HarryM1BYT

Thats unusual. So pulling that fuse would isolate the alternator from the rest of the system and the battery, thus preventing the alternator discharging the battery assuming it might be doing that?

I guess really that if you thought a diode in the alternator was leaking the battery down to earth you would simply take the cable off the alternator.

Taking out that fuse would probably stop the car.

[COLVERT]

Originally Posted by David F

So you don't think I should have any problems getting to the garage tomorrow, it's about 25 miles, should take 45 minutes more or less depending on traffic.
What is actually using the battery when the engine is running, I assume the fuel pumps, any lights, the ECU ( very little power I would have thought) The cooling fan ( but on a cold day and at speed it shouldn't kick in)
I really don't want to stop half way!

Don't forget. Come back and tell us how you got on.

[rover54]

Originally Posted by julienhoulton

My son has a 1.8 club. new battery, warning light came on, tested alternator pushing out 12.5 volts.

What I am asking is there anything in between the alternator and battery that might be disrupting the charge IE fuse etc!!.

Julien

Alternator should be putting out more than 12.5 volts. Normally that are around 14.5+ volts to overcome internal resistance of battery. That is why warning light is on as it is not really charging.

[rover54]

Originally Posted by HarryM1BYT

Thats unusual. So pulling that fuse would isolate the alternator from the rest of the system and the battery, thus preventing the alternator discharging the battery assuming it might be doing that?

It is a fuseable link, a strip of metal, it cannot be removed like a normal fuse.