ENGINE AR-COMPLETE 1877982 - Caterpillar

Never disconnect any charging unit circuit or battery circuit cable from the battery when the charging unit is operated. A spark can cause an explosion from the flammable vapor mixture of hydrogen and oxygen that is released from the electrolyte through the battery outlets. Injury to personnel can be the result.
The battery circuit is an electrical load on the charging unit. The load is variable because of the condition of the charge in the battery.
The charging unit will be damaged if the connections between the battery and the charging unit are broken while in operation. Damage occurs because the load from the battery is lost and because there is an increase in charging voltage. High voltage will damage the charging unit, the regulator, and other electrical components.
Use the 4C-4911 Battery Load Tester in order to test a battery that does not maintain a charge when the battery is active. Refer to Operating Manual, SEHS9249 for detailed instruction on the use of the 4C-4911 Battery Load Tester. See Special Instruction, SEHS7633 for the correct procedure and for the specifications to use when you test the batteries.