COUPLING-PERM 1242253 - Caterpillar

new Cat products are now using maintenance-free batteries. These batteries require different test procedures from conventional batteries. Since there are no vent plugs on maintenance-free batteries, there is no way to check the specific gravity of the electrolyte. A hydrometer cannot be used. Instead, the voltage of the battery must be checked to determine the state of charge.
Measure the open circuit voltage of the battery. Use a digital volt meter such as 6V7070 Multimeter Group. Set the meter on the 20 volt DC scale and touch the probes to the battery terminals. If the battery voltage is 12.40 or above, the battery is ready for use. If below 12.40 volts, it must be recharged for satisfactory performance.
If a maintenance-free battery is being considered for warranty, the same voltage check must be done before performing a load test. Maintenance-free batteries below 12.40 volts will fail a load test, but still may be good, serviceable batteries when recharged.
When maintenance-free batteries are deeply discharged, they may not recharge if you just jump-start the engine. Cat alternators produce 13.8 volts on 12 volt products and 27.5 volts on 24 volt products. But 16 volts (32 volts on 24 volt systems) may be required for charging to begin. Recharge with a battery charger capable of supplying 16 volts so that the batteries will accept a charge. Once they accept charging current, indicated by an increase in the charger ammeter reading, the voltage must then be reduced. It is important not to let the charging voltage exceed 16.0 volts, especially as the battery becomes fully charged.
The Cat maintenance-free battery used in original equipment (3T5760) is designed and built to rigid Cat specifications. It can be deeply discharged, such as by leaving the lights on over a weekend, and still be a good serviceable battery when fully recharged. For complete testing and charging information, refer to Special Instruction, Form SEHS7633, "Battery Test Procedure."