I have a problem with my electrical system that is driving me crazy. I have a trunk mounted battery that show's 12.6 volts until I connect the positive and negative battery cables to it then the voltage increases to no end. I don't have to start the car but only connect the cables and turn ignition switch over to ignition 1. I thought it was the battery and replaced it with a new one only to experience this same phenomenon. The voltage will continue over 15 volts before removing the cables. After removing cables the batteries will subside after a couple hours and read normal voltage for a sitting battery. Again, this is my second battery and the engine isn't even running so I'm thinking it has to be in my wiring. I know this is a weird problem and I can't find a thing on the internet pertaining to it. Anything you can throw at me will be appreciated. Greg
Battery Voltage Increases Without Engine Running
- Thread starter ykf7b0
- Start date
69hemibeep
Sponge Bob Square Wheels
Can I plug my house into it :jester: Don't know what to tell you on that one.
Ranger
Well-Known Member
:huh: That defies logic
quikbird
Well-Known Member
I am still stumped as well but what the heck, let's see if we can start figuring it out. how long ago did you move the battery? did it work normally for a while before the current issues? Have you replaced anything else lately, alt or regulator? what kind of alt are you running? does anything else behave strangely such as gauges? are you using a standard wiring setup going through the ammeter? the answers to all of that should give the rest of us a better idea what you currently 
rimshot have for a setup.
rimshot have for a setup.Battery has been located inside the trunk for the past 15 years and worked great. I initially noticed the tach would peg out and die but then start functioning correctly. A few weeks later I noticed the aftermarket volt gauge began to fluctuate then it pegged out. This is when I began my diagnosis. I have since replaced the battery, voltage regulator twice, regulator pigtail, new field wire from alternator to ballast, ballast resistor, and alternator. The alternator that I removed was a squareback 75 amp powermaster and I now have a squareback 65 amp alternator from Advance Auto. The factory alternator gauge has been bypassed as recommended by Mad Electrical. I'm confused on whether the battery is causing my problems or my problem(s) are causing my battery to go ballistic. Thanks for your inquiry!I am still stumped as well but what the heck, let's see if we can start figuring it out. how long ago did you move the battery? did it work normally for a while before the current issues? Have you replaced anything else lately, alt or regulator? what kind of alt are you running? does anything else behave strangely such as gauges? are you using a standard wiring setup going through the ammeter? the answers to all of that should give the rest of us a better idea what you currently
quikbird
Well-Known Member
Doesn't sound like battery. If nothing happens until you turn on the key it is in the wiring somewhere. Sounds like a feedback from somewhere in the system. That or something is grounding somewhere it is not supposed to and really starting to pull some current. Possibly inside some part. Best suggestion is get a few friends to help and all watch and see if anything smokes, sparks or makes any noise when you put on the key.
Ranger
Well-Known Member
Holy fried battery Batman! It was self inflicted and lived like that for 17 years?
Please elaborate on how the battery can charge while the engine is off. Inquiring minds want to know.
Please elaborate on how the battery can charge while the engine is off. Inquiring minds want to know.
The best I can tell is that a ballast wire was being fed to the voltage regulator by an unused tach wire that was in the engine harness. I still don't know how or why this could cause the self battery charging. It must have been some kind of reverse charge or stored charge making it's way back to the battery. It's voodoo!
quikbird
Well-Known Member
Glad you found it!
Thank you!!! Thanks to all who chimed in!!!!