Electrical issues,

hey guys, im having some electrical issues with my jeep, i have a 97 4.0 2wd, it wont start rite now but if i have someone jump me i can power brake the thing around, the jeep has been doing this the last couple weeks, the first thing i thought it was, was the battery the one that was in there had a cracked post so i figured it was having intermittent shorts, so i went out and spent $200 on an optima and not even a week later it does it again. today i got in the jeep it started up fine, i drove to 7/11 to get a drink, come back out, turn the key and all i get is a click? how did the battery loose power? idk. also yesterday i was driving my girl to get her hair did and the check gauges light came on and the battery voltage was all the way up to 19. what causes that?! rite now the jeep wont start at all and the lights dont even come on when i open the door. could this be alternator? voltage regulator? im just stumped... any input is appriciated. thanks!

Ok.

You probably have a bad Nippon Denso alternator. The alternator's charging is controlled by the PCM--the engine management computer.

Quick test--fully charge the battery. Put a voltmeter between the battery posts. Should read 12.5 volts. Start the engine, should read 13 to 15.3 volts.

Note: chain parts stores that offer free alternator testing have problems getting it right with the externally regulated Nippon Denso alterators--they usually report them as "good" when they are "bad". Locate a competent alternator shop in your area and have them test it.

I have discounted the possibility of a bad/dirty cable(s) based on the information you provided, but checking/cleaning is never a bad idea, although I think you likely did that when you changed the battery.

Good luck.

thank you joe! ill charge the battery tomorrow and test it on wed. and get back to you. again, thanks!