Ok here is the scoop. For the last few months my car voltage has been dropping down to 8 volts everytime i idle. When cruising at a high RPM my voltage goes all the way up to 13 volts. Is my battery shot? or alternator? Also, for the past week, my car will just kill while driving at a low RPM, when it kills i have no power whatsoever. I can keep the lights on and everything. While the car is sitting like that, after about 10 minutes, evverything lights up again and i have power instantly. I am getting very frusterated at this point. What can make my battery current just kill instantly and come back on 10 minutes later?? the battery connections are all tight. Its almost like its shorting out, but why would it go back to normal?? Please help. Any help is GREATLY appreciated. Thaks for your time- Tim

 

Try a new battery...Seriously. The voltage dropping and rising like that could also be the voltage regualtor. But seeing as the voltage doesnt go OVER 13 volts (which is good), I would say battery. Youre gonna want to do somehting as the voltage varying like that is not good for the regulator at all. It can actually fry your alt if its trying too hard charge the battery. Also, check all your electrical connection on the battery, the grounds and the alternator. You could also check the ouput of the alternator by taking a volt meter, put the positive on the wire coming oput the back that goes to the battery, and the negative on the alternator casing to ground it. Mine reads about 13.5 volts constantly...Mines brand new though...Im thinking maybe your battery is dying because its not taking a good charge, then after you let it sit, its got some power again. I dont really know though. I just diasgnosed my problem which was VERY similar to yours...You can search for "Now I have a damn electrical p[roblem"
and Im sure you'll find it. I ended up with a new alt AND battery. I got the new alt thinking that was the problem, turned out I had the same problem with the old battery. It was the battery not taking a charge, but my old alt was dead also. Anyway, after the new battery and alternator, all was well. Basically, just get a new battery and see what kinda wonderful things it will do for you.

~T.J.

EDIT: Heres the link cause I was feeling nice

https://www.rx7club.com/forum/showth...trical+problem