Alternator on 100s TD

Under "average" driving conditions, some alternators will give upward of 200 000 klm before needing a rebuild. Brush wear is significantly reduced with dust though, and if the veicle is driven through a slurry type of mud and then left to dry, the brushes will get stuck in their holders and not keep contact with the sliprings. This is very common in mining vehicles etc. Most alternators on todays 4wd's have an output upward of 100 amps. This creates a huge amount of heat for the internal components, ie diodes and regulator. (P = V x I). Heat is a very quick way to destroy any type of electronics, as we all know. The size and cooling methods of an alternator have not really changed in 30 years, just the output has increased. It would be fairly safe to say that the under bonnet temperature is today, some what greater than 20 or so years ago. Electronic components have improved in quality also, but it is a fairly safe bet that if you are running all the equipment on your average 4wd in a harsh environment for extended periods, 100 000 klm's is probably considered good. Alternators on taxi's are generally not given any warranty, or if so, 3 months. Just as a comparison.
In short, your alternator could be in need of a new regulator or rectifier, but there may also be a wiring problem. Check your battery voltage with the engine running at about 1500 rpm and everything electrical switched on. If it is between 13 and about 14.4, it is probably still charging your battery. If this is the case, next time you are getting a wheel alignment on the IFS, have them check the alternator also.....LOL.
Hope this Helps.

Agree with above.
If you ever need a new one, give this mob a go. I've used them twice and can highly recommend- very competitive price, good service.

www.aea.com.au/shopping/index.html