silver91gt

I have a charging problem, I got a new alternator and I tested the volts to the batt when running, and it was 13.5 it seems a little low, but I thought because of my underdrive pulleys,
then I drove it for 10-15 minutes and my temp went up to 220 and stayed there, because my low charging wasnt letting the fan run at full power.

I got home and checked the voltage and it was only 11.5 when running.
I let it sit for a while and the voltage went up to 12.11volts on the battery.

I thought my alternator went bad again, so I brought it back to the part store and it tested ok.
is there anything else inbetween the alt and battery that I can check?

the guy at the parts store said it could be a relay or something.

does anyone know how hot alternators are supposed to get.
when I first noticed the low voltage I went to check the connections and the alternator case was so hot it almost burned me.


please help

silver91gt

up

dc_mann8

you must have an elec fan?

silver91gt

yes I do, is this the problem?
the fan takes less than 20 amps to run it.

birdman076

Check your grounds and replace any cables that look suspect, go bigger if possible. The temp on the alt casing is a giveaway for a bad ground or a short, electronic components heat up for 3 reasons. 1 no or bad ground that doesn't allow the heat to be bled off, 2 they are going bad, 3 improper ventalation. I always run at least 1 step bigger cable on the ground side for my own piece of mind, you could have a bad connection, one that isn't clean, bad cable, or a bad alternator. The test at the parts store only tells if its charging or not charging, not if a diode is on the way out or not.

mustang8719

If it is the stock alternator you should upgrade it.
That fan is sucking tons of juice from the alternator.

roundman

are you using a relay to supply power to the fan?? this makes sure the fan gets full battery voltage instead of having the current to it flow through the switch which can create a current drop.

silver91gt

yes I have a 50 amp relay with 25 amp fuse.
but I wired the power to the switched side of the solenoid so it wont come on after the ignition is off.
I also have 5 extra gauges, and 3 of them are wired with the light on when the car is on.
I didnt want to take apart my dash, so I wired them to a fuse in the fuse panel.

other than that I don't know what would cause this.
how much of a drop do underdrive pulleys make, with the stock alt one?

5.0mustang5speed

voltage regulator

silver91gt

if the voltage regulator went bad wouldn't their machine that tests it say the regulator is bad?

I had the old alternator checked at the parts store and it said it was good, but I upgraded to the 3 yr warrenty one, made by bosch.
I hope this one is good