Recommended alternator?

[airdrew99]

I'm having some problems with my alternator on my truck. It puts out 14.2 volts at idle with no accessories turned on. As soon as I turn on headlights, radio, and a/c with blower on high (all at the same time), the voltage drops to 13.7 volts and stays at that number and never rises until I turn everything back off. Even after 2 minutes the voltage stays at 13.7 volts with all accessories on.

Also, I had the alternator off the vehicle and took it to the auto parts stores to load test. Two different Advance Auto stores showed the alternator as "Passed". I took it to Autozone and it showed "Failed". None of these stores showed any values, just pass or fail.

Has anyone else tested voltage drop with and without a load? What kind of results did you get?

Also, can someone recommend a good aftermarket alternator with a little bit higher output then the original 110 amps? I'm thinking at least 130-150 amps. Thoughts/opinions would be greatly appreciated.

By the way, we just found out today that we are having a girl!!!!! We already have two boys.

Drew

 

[JRJ04]

Drew,

Congrats on the girl! As for the alternator...I'm not sure you've got a problem. Unless it continues to fall, I'm not sure I'd worry about it. I think there's bound to be some slippage when there's a load on it. Does it come back up at all when you've got it revved up (like going 70 mph turning ~2K rpms)? Others will chime in, but I dont know that you're going to gain much by upgrading unless you're putting a really big load on it (like aftermarket lights, running PTO items etc.)

 

[airdrew99]

Even after revving to 1,200-1,300 RPM, it stays at 13.7 volts. I have a brother that has the same truck and engine as I do. He said his recovers within 1-2 seconds of turning everything on. By recovering, I mean his voltage immediately goes back up over 14 volts. I have two Interstate 1000 cranking amp batteries that are about 3 months old. I've just always thought that my alternator is not putting out enough. After driving for 30 minutes to an hour, I can go out and charge my batteries on 10 amps and they will usually go for 3-4 hours before they are fully charged.

 

[nswsparky]

I don't think there is anyting wrong I have a digital volt gauge in my truck and it is always going from 14.5 down to 12.5 it seems to switch on and off by itself and I have a brand new alternator and not a cheap one.