High output alternator experience

[smshield]

You're original problem as stated was exactly what I had wrong with my Jeep wrangler (2000). Replaced the alternator with a new one and the battery. Dodgy battery ate my alternator.

On the upside, I too replaced mine with the highest output one I could get my hands on. Whole truck runs better in every way. She loves having more volts.

[JoeH]

Back in to fix the AC so I thought I'd add wrap this up. More on the AC later. Here's a better pic of the 250A DCpower alternator which bolted right up. The components are all USA made. Nothing from china. Be careful out there when you're alternator shopping. The Fuse block is part #782-1143 and the 250A fuse is #782-1142 from NAPA.

The only issue with the install was the alternator was initially putting out too much voltage. The inst. panel charge light was staying on and the indicated output voltage was reading 15.2-15.7 volts! My mechanic had to modify a wire on the harness where it plugs into the factory plug. That took care of the bias voltage. According to DCpower the issue with the voltage is that some of the ford alternators slowly kill a crucial wire that reports back to the alternator about the voltage it's putting out. What happens is that wire gets more and more resistant to voltage and then the alternator thinks that it's not putting out enough voltage so it compensates for the bad wire. Lots of current through a small wire for a long period of time = heat. Excessive heat = damaged wire = added resistance. Because of the damaged wire the PCM wasn't getting proper voltage feedback.

With the modification, everything is peachy. Now, overall voltage is a max of 14.1 to 14.3 (at the Scanguage I have plugged into the ODBI port). And I’m also getting a steady 48.5 to 49 voltage output on the FICM which was a concern with the failing alternator. Because of the upgraded power cables, the unexpected bonus here is that it allows the alternator to begin charging the batteries immediately upon startup rather than having to wait for the glow plugs to turn off before charging is allowed as with the stock set up. That's quite a substantial draw-down on the batteries. The stock alternator is truly undersized for the application as it puts out only 65 amps at idle.