I have a digi fuse box and I havn't the foggiest idea of what the numbers mean. I know the battery is 12v and i heard most car audio systems are about 13.5 or 14v. Sometimes the read-out is 15.1. What numbers are bad the lower or the higher ones? I hope ya'll under stand what Im talking about becuz i think i lost myself!!
Car bateries hold a charge of 12 volts, however altenators put out 13.5 to 14.4 normally. Thats why stereo makes rate amps at 12 (car not running) and 14.4 (car running). The numbers you are looking at is the voltage your system is running at. 15.1 is a little higher than I like. If it gets to much higher it could mess your amps . Most have a protection circut designed to shut off at around 15.5, however I would rather be safe than sorry. I would take a volt meter and check the volts at the battery, and at the fuse block (with the car running). If it reads diffrent remember the diffrence for future trouble shooting. As for bad #s, if the car is running and you are reading around 12 volts then the alt is bad. If it starts reading over 15, or the voltage is peaking, (moving back and forth between a lower # and a number in the high 14s or any were in the 15s then look into a new altenator. I would hate to see your alt peak and fry your amps. As for the numbers in between, they are all ok. Perfect would be 14.4 at all times, but voltage is dependant on amperage, and resistance. In other words the more stuff you have on, the more your alt has to put out to keep every thing going.