mikeha ... 3/14/2019
2007 Chevrolet Colorado WT 4 Cyl 2.90L
Why would my truck have issues starting / maintain high voltage
The alternator is NOT on during starting, so immediately after the heavy load of starting, the voltage will read in the 11+ volt range. After the engine is up to speed for a 2 to 5 seconds, the computer turns on the alternator and the voltage goes to 14.1 or 14.2 volts. After that the alternator maintains 13.8 to 14.2 volts. Running in the 13.8 range as the alternator and battery gets warmer. This exactly meets specs for charging a lead acid battery. The spec is 13.8 to 14.2 charging voltage. Charging at voltages higher than 14.3 will cause the battery to gas (boil).