Join Date: Jul 2012
Location: Detroit, Michigan
Unplug the regulator connector from the alternator, this should put the alternator in full field and charge at max. If it stays at 14.50 or above while it running, then its a regulator issue, if not replace the alternator. Also, there is a wire in that regulator connector that is the battery sense wire. This wire detects battery state and charge, if there is excessive resistance in this circuit, it will not charge properly. The connector has 3 wire in it, one of them should have battery voltage at all times. Check resistance from that wire to the battery positive, the spec if 5 ohms or less. If its excessively higher than that, then clean your battery terminals and recheck it. If it's still excessive, use a jumper on that hot wire in the regulator connector, and jump it right to the battery lead on the alternator itself. 14.8V is overcharging, anything over 14.5V is overcharging and will cook the battery. This could be due to the battery needing to be replaced, need to charge the battery and load test it to be sure. The alternator should not drop below 12.5v at all while its running. Sounds to me you have a bad battery and faulty charging system that probably killed your battery. 14.8V overcharges that battery and kills cells inside of it, and anything under 12.5V is not charging. If it hits 14.8V that could be cause of a bad battery. Installing a new battery could change that, but would still need to have the charging system looked at as i described above.