Charging system woes

[Big Port Jimmy 6]

87 r2500 01 5.3 4l60E with 25k miles on the swap. I have never been satisfied with the charging on this truck. Best I have ever seen is 13.8 at 2k rpm usually 13.2-13.4 at idle. Will not bring the battery back up if its weak and with the Headlights and AC the voltmeter plummets. I have wired it back to the stock wire from the lamp in the truck, I wired it originally to the PCM with no difference in results. This is the 3rd Alt. went from the low amp to the high amp unit first and the high amp unit had a bearing failure, but all charged approx. the same. Using a DVOM on the batt to get my readings. Is there a 1 wire regulator for these? Is there an old style alt that will fit the bracket? Thanks Jay

[clinebarger]

It's most likely not the Alternator itself.

The Alternators job is to maintain the battery, Not to charge a weak/discharged battery.

Have you checked the voltage at the output post on the alternator, If it is showing 14 plus volts & the Battery is showing 13.2 volts....You have a Voltage drop (resistance) between the Battery & Alternator. I usually use at least an 8 gauge charge wire.
Don't forget that the Alternator is grounded through the bracket, A painted bracket will cause issues if all the mounting points are not cleaned.