Well I seem to have a charging issue maybe? I have just put a new battery in my car, because it wouldn't start the other day. My Apexi commander usually reads out at 14.9v max at speed, but once it idles it goes to maybe 12.1 at it's lowest. Sometimes at idle it will be around 13.5v. I think my low idle (600rpm) has a little to do with this, but it doesn't happen all the time. My question. Is my voltage reg gone bad due to the high 14.9v at driving speed? Everytime i start the car the batt shows around 12.1v. I work at a batt store so I have access to new batts all the time. This is the 3rd on in little over a year. I think the last one went basd due to overcharging. What should volts be at 700+ idle?

 

does sound like your alternator ... i would just replace it. usually a jumping voltage can also be a loose belt maybe a connection starting to get loose...start with the alternator ... if you just replaced your battery then you shouldn't have to worry about that

 

i would expect voltage to be down a little bit if the car is idling low. an alternator's output is very dependent on rpm