03DelcoRemy Diagnostic Manual130004222020

delcoremy.com Page 7 There are three types of lead acid batteries used in commercial vehicle applications today: the maintenance-free flooded electrolyte battery, the AGM battery, and the Thin Plate Pure Lead (TPPL) AGM battery. Unlike maintenance-free, flooded, lead acid batteries that have liquid electrolyte, an AGM battery contains a glass mat separator made of fiberglass that is placed between each plate to absorb the electrolyte. Fleets should prevent batteries from becoming deeply discharged—dropping to less than 10 volts due to extended storage with vehicle support loads. Also, trying to start trucks with a low state of charge or weak capacity batteries can cause high amperages and low voltages. This can overheat the starter motor and damage battery cables. A voltmeter on the battery terminals will indicate the battery’s State of Charge (SOC). State of Charge Flooded Battery AGM Battery TPPL AGM Battery 100% 12.70+ 12.80+ 12.84+ 75% 12.40 12.60 12.50 50% 12.20 12.30 12.20 25% 12.00 12.00 11.90 0% 11.80 11.80 11.50