2nd Reman Alt and Still Have Voltage Issues....

[zeus201]

Need some opinions on my voltage issues I am seeing with my 03/04 Cobra Conversion. Car has a 8lb lower with 3.7 alt pulley.

I am on my 2nd reman alternator and just picked up a new stock battery within the last two weeks. With both reman alternators, readings from my Xcal3 or Aeroforce gauge shows voltage at startup around 14.X volts. Once everything is up to temperature, voltage is around 13.0 - 13.2 volts. I haven't gone WOT for fear of leaning out.

Voltage across the battery reads 14.X at startup, but once everything is up to temperature, voltage reads around 13.5. The battery shows 12.5 - 12.6 volts at rest.

I have inspected the grounds within the engine bay and they appear fine. I have gone out and bought electrical cleaners and will start cleaning all connections and grounds today and probably replace the belt as it has a little give. The previous three summers, voltage was always around 13.9 to 14.1 volts no matter what accessory was running which makes this really frustrating.

Any suggestions...

Ryan

 

[03yellow]

Where did you get the reman alt?

 

[Wayneo]

Is the 3.7 alternator pulley stock size, smaller, bigger? If its bigger that could be your problem right there. Double check all your ground wires for high resistance and voltage drop your power cable from your alternator to your battery to make sure your not loosing voltage in between. Good starting point. Does the voltage increase from 13.5 when engine rpm is increased?

 

[03yellow]

If you purchased your alt at a parts store you have a 90 or 110 amp alt. Our alts are 130 amp. If you had it rebuilt and did not tell them it is 130 amp then they rebuilt it at 90 amps.

 

[zeus201]

Where did you get the reman alt?

Is the 3.7 alternator pulley stock size, smaller, bigger? If its bigger that could be your problem right there. Double check all your ground wires for high resistance and voltage drop your power cable from your alternator to your battery to make sure your not loosing voltage in between. Good starting point. Does the voltage increase from 13.5 when engine rpm is increased?

There is no voltage increase when I increase the rpms. I will check the voltage drop between the alt and battery! However, it is my understanding that when you running an 8lb lower, a larger alternator pulley (3.7) is recommended as the stock pulley will cause the alternator to overspin.

If you purchased your alt at a parts store you have a 90 or 110 amp alt. Our alts are 130 amp. If you had it rebuilt and did not tell them it is 130 amp then they rebuilt it at 90 amps.

I forgot to say...both units are Ford Remans I picked up through Tousley.

 

[jm@ReischePerf]

voltage at startup around 14.X volts. Once everything is up to temperature, voltage is around 13.0 - 13.2 volts

That sounds pretty typical in the summer heat, in the cooler weather your voltages will probably be higher. Keep in mind as long as you see higher than batt voltage (12.6V for you) the alt is doing it's job.

 

[shanezt]

13.5 is fine

 

[Nutty 5.0]

For reference I have one of Start 'N Charge's alt's with 3.2" pulley since I'm running 4# lower and 2.93 due to the port and with the KB boost a pump and everything else in the heat I see 12.8-12.9 at WOT voltage via Scangauge...