3rd aluternator in a year help

[JohnWilson]

I am on my 3rd aluternator in a year first one dropped voltage second one spiked to 20 and now this one not charging I testing batt it was 12.89 started it then it read 12.32 and went down to below 12 when I took it above 2000rpm help it is starting to cost a lot in parts

[nb422]

Sounds like more of an underlying fault further back. Do you replace the charge relay with the alternator? Also is it taken offroad very often??
The auto sparky told me that if the relay is not replaced it can potentially cook the alternator but possibly there could be a short circuit or something along those lines.

[geeves]

charge relay likely cause
Also an intermitant dis in the wiring can blow an alternator. It might just need a brush clean. I had one alternator with a sticky brush that would stop charging untill taken out cleaned and put back every few months.
Im on my third alternator too but thats over 19 years

[JohnWilson]

when I put the second one in I put relay that was in the truck it came out of in my truck

[JohnWilson]

think this might be the problem for no power this time 8mm nut came off and cooked itself

[geeves]

could be. Who didnt tighten it properly?

[JohnWilson]

second hand the rubber bit was over it when I put it in so didn't see it was loose but the guy got it off been good about it droping of another one soon for me to use and he getting it fix for me

[JohnWilson]

just finished rebuilding a aluternater for under $100 for rectifier brushes and regulater

[PETERDIESEL]

I know this a bit late but have had 2 alternators stop charging which I believe was caused by a intermittent battery earth connection where it attatched to the A/C compressor. The L shaped metal terminal looked and felt ok but when I pulled it apart I found evidence of high resistance. The intemittent connection probably was the cause as at times there may have been almost no electrical connection. This is an unusual problem but may be common my model and others similar.