Quote: Originally Posted by shrinkydinx
and cars go from lik 8-17

if your car's voltage is spiking from 8 to 17 volts, you have problems. At no point during vehicle operation should your charging system EVER produce more than 14 volts. When your battery is low, say after cranking or even a dead battery running from say a jump start, your alternator will go full field and supply maximum voltage to your battery and electrical system. This will be 13.8 volts, +/- .2v.