Heres the issue, start the car up, gauge in car read 13-14 volts. Go to battery terminals, i get 13-14 volts. Take care for a lil drive (still workin out tuning since 383 install) alt gaugein car goes up to 17 volts halfway through a drive. Roughly around a couple blocks. Go to read voltage at battery while car is running it reads 12.5, but the gauge in car reads 17. Had alternator checked at parts store, checks good. Im lost now. Any ideas?

 

If I remember correctly the voltage gauges in these cars aren't the most reliable things. That could be part of your issue.

Does your battery just continue to lose power or does it stay at the 12.5 once it drops there?

 

Sounds like a bad regulator in the alternator or a bad diode in the bridge119. These units will heat up and either open or short with heat. Just a quick test on an alternator machine will not duplicate the heat. Suggest either replace regulator and rectifier bridge, check brushes while doing this or replace alternator. Alternators run from $59.95 at Parts Geek to $192.47 at Rakuten and $72 on Amazon. Looks cheap enough to just replace it.

 

Voltage on battery stays at 12.5 while car is running. Shut it down and it wont crank over again. Put battery on charge, start cranks over and runs again and get same results. Next pay check if $$$ is left over from bills ill put a new alternator on it and hopefully that will fix it.

 

Have the battery tested as well, it's free at any parts store. I'd also check for any shorts to see if the battery is draining while the car is off.

 

I work at advance part time. 2nd job. Ive tested the battery and alternator and both test good. Did a drain test, at my house, 0.3 amps which is passing on our test machine at work. My next step is to drive the car up to work and actually put it on the test machine instead of bench testing. The only bad thing is the car isnt insured yet.....long story... basically whole drivetrain swap + deployments= car sat for awhile.