Alternator Failure?

Thanks so much

I have to do the timing belt at next service so it would seem to be a perfect time to replace the alternator also and do this wiring mod.

I cannot seem to determine what the correct fuse would be for the 2.7?

Richard

So has anyone that has had this failure had any damage occur to the starter motor.


If the starter is getting damaged then its more reason to fuse between the Alternator - Starter.


I am looking at fusing at the battery end unless someone has had starter damage , then I will do it as Graeme suggests.




Cheers Ean

I hope that you aren't intending to fuse the starter lead as it already has a 500A fuse at the battery.

A hight current draw by the alternator such as due to diodes reverse conducting will have no effect of the starter motor or its solenoid.

Quote:

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Originally Posted by Graeme

I hope that you aren't intending to fuse the starter lead as it already has a 500A fuse at the battery.

A hight current draw by the alternator such as due to diodes reverse conducting will have no effect of the starter motor or its solenoid.

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I may have mis-understood the conversation, but I assumed the 500A fuse is part of the issue as it will never blow. If you install a 200A fuse somewhere between the battery and Alternator either before or after the starter if should have the same effect.


As long as you know where the fuse is in case of charging failure the same result should be achieved... Correct ?


Cheers Ean

Quote:

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Originally Posted by PerthDisco

I cannot seem to determine what the correct fuse would be for the 2.7?

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My guess is one about 20A higher than the alternator's rated maximum output current - the 2.7 D4's alternator is rated at 150A @ 25deg C so 170A. Make sure the cable is rated to carry at least that current - don't want to overheat the cable instead of blowing the fuse.

Quote:

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Originally Posted by Ean Austral

As long as you know where the fuse is in case of charging failure the same result should be achieved... Correct ?

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Yes.

Quote:

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Originally Posted by Ean Austral

I may have mis-understood the conversation, but I assumed the 500A fuse is part of the issue as it will never blow. If you install a 200A fuse somewhere between the battery and Alternator either before or after the starter if should have the same effect.

As long as you know where the fuse is in case of charging failure the same result should be achieved... Correct ?

Cheers Ean

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But if the 200A goes before the starter won't that take over the role of the 500A fuse? Presumably the starter can require more than 200A if it is protected by a 500A fuse?

Cheers, Scott

I missed that remark.

Either fit a fuse in a new dedicated alternator cable direct from the battery and cut off the short starter to alternator cable where it joins the battery to starter motor cable at the starter motor solenoid or fit a fuse in the short starter to alternator cable. The 500A fuse for the starter motor in the battery to starter motor cable must remain.

After thinking about it I can see the problem with fusing the battery - starter cable , this creates issues with the start circuit.


Fusing the Alternator to starter side fuses the charging circuit, which is the circuit that will stop if the alternator shorts, leaving the start circuit in full normal operation.


the penny has finally dropped.


Cheers Ean

I finally installed a dedicated alternator B+ cable on my 3.0 today. Its 2m long, enclosed in fluted sheath, cable-tied to the starter cable at various points and is fitted with a 200A fuse just prior to connecting to the battery. My backup/spare fuse is 225A, being the next higher rated one in case 200A isn't quite enough for the 180A-rated alternator.

The alternator B+ stud was accessed from below rather than drain coolant, remove the fan, ancillary belt, tensioner and the alternator. The cable from the starter has yet to be cut off, temporarily held out of harm's way with several cable-ties - a job for another day. Lost some skin but that's mechanicing.