Think the alternator is going, when running in park under load (grille lights and system on but not pumping) battery gauge is dropping below midway point when it used to be past mid and lights are kind of dim. Cut off the grille lights or rev it a little and batt gauge comes back up and lights brighten. Haven't had a chance to poke around with the multimeter yet, but I'm leaning toward it being the alternator.. The battery was a brand new one that someone put in a volvo it didn't belong in. Any good brands? And i'm looking to upgrade, is 140a enough or should I look for bigger? Also how are reman units?

 

I have the exact same problem when I hook up my boat and turn on the trailer lights. Try out this one for one bad-a$$ alternator.

https://www.dcpowerinc.com/high-outp...e=5.7L+Hemi+V8

 

Yeah it's no more load than usual. I mean I did just swap the battery maybe a month ago, but this issue is very recent. Could be the battery since it was used... But it was brand new in that Volvo... Old man has been a mechanic his entire life, wouldn't give me a battery thats trash... I'll mess around with the meter tomorrow. For now, Budweiser.

 

Well I put a multi-meter on mine and the voltage was good, but then used a battery tester and it just doesn't hold the load. It's the Alternator.

 

I can't afford that gen lol.

 

Raman units generally all have new bearings and the case cleaned. They'll re-use the stator, rectifier and brushes if not worn out, so essentially, you get an alternator that's "good" at the time of purchase that has been previously used.
Sounds to me like you've lost some of your rectifier diodes which reduces the output given.
Rebuilding them isnt hard if you know what you are doing, finding the correct parts can be a challenge.
You can buy New alternators at Advance auto. I bought a new Delco for my Beater. It was $35 more than the Reman unit plus there was no core charge!
New Bosch unit for $117shipped
I know local auto stores are getting more than that for Reman'd units!

 

Yeah I was looking at those bosch's.

 

This just happened to me. Switched from the 136 amp to 170 or 180 cant remember. No problems since

 

11.9-12.9v at the battery while off. 13.9v while idle 13.75v running with all lights on. Seems the alt is ok. Gauge in dash is at the low side of the "ok" box while engine off, and a little under the mid mark at idle. Lights still dimming a little until I rev the engine... Any ideas?

 

Start The truck and pull the neg. Battery cable if it dies your alternator is shot.