Charging voltage low

[JustinStone]

After a recent rebuild of my engine, the charging voltage has been reduced to 13.5v from 14.7v. the cables were not disconnected from battery terminals, and everything is damn tight. It will jump from 13.5 to 14.5 or 14.7 sometimes on start-up, but there is no relation to battery temp; it will go back to 13.2 after restarting the car. I replaced the alternator's pigtail connector during the rebuild and repainted the block, but the crimps we're hella tight and the paint was scrubbed off the ground location. Not sure what's going on

All batteries tested with ctek charger, and the 5 month old 300 amp alternator keeps the voltage at 13 from 13.2 even while full tilt at 2500 watts. It seems like a regulator issue, but I've switched tunes and the issue still persists?

Maybe the pcm isnt getting a good ground, or the battery to block ground wire needs to be replaced.

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[Zman2k2]

I know on my alt. (Toyota), there’s an alternator sensing circuit called “Alt-S”. I’ve put a diode in mine to boost the charging voltage to 14.6 cold and 14.2 hot.

Another thing is the pigtail replacement. Check the connectors, one may be loose or corroded.

 

[JustinStone]

I know on my alt. (Toyota), there’s an alternator sensing circuit called “Alt-S”. I’ve put a diode in mine to boost the charging voltage to 14.6 cold and 14.2 hot.

Another thing is the pigtail replacement. Check the connectors, one may be loose or corroded.

The pigtail is brand-new, 3 days old. I'll re-strip and crimp it to see if that works; I'm thinking the terminals are fine, but I'll give them a check too.

I'm not sure if the diode trick would work? The pt cruiser's alternator is controlled by the pcm, and so far I've had to get new tunes in order to change the voltage.

 

[Zman2k2]

Yeah, if it’s PCM controlled, there’s no diode trick. Wondering if it’s crossed wires at the on the pigtail. Any way to confirm color coding?

 

[JustinStone]

Yeah, if it’s PCM controlled, there’s no diode trick. Wondering if it’s crossed wires at the on the pigtail. Any way to confirm color coding?

the issue was in the battery temp sensor parameters. here in florida the ambient temp is 100 and the temp sensor is set to reduce charging voltage at 90 degrees. after changing those parameters the charging voltage now rests at 14.8-9

 

[1aespinoza 10+ year member]

after changing those parameter

How did you change the parameters?

 

[JustinStone]

How did you change the parameters?

For the pt cruiser, neons, and other pcm controlled charging systems these parameters need to be altered with tuning software. The two tuners I recommended and have used are the hp tuner and Diablo tuner platform. With HP these parameters can be adjusted by the user, with the Diablo platform the parameters are adjusted via a custom tune written by a third-party tuner. I haven't looked into it, but I'd assume there's also a way to flash an adjustment onto the pcm without owning a $400 tool. It was convenient that I had already been using tuning software.