A winch battery is a battery dedicated to operating a power winch. Often used on a vehicle-mounted winch, a winch battery is commonly a second battery that allows the winch to operate without draining the primary battery. The winch battery is commonly wired directly into the power winch to eliminate any blown fuses, overheated wiring harnesses and burned wiring connections. The most recommended type of battery to use as a dedicated winch power supply is usually a deep-cycle, marine-type battery. Other variations of the power supply are two six-volt batteries wired to provide 12 volts. This provides extended winching power for severe-duty applications.
When wiring a winch, it is important to eliminate any type of fuse between the winch and the winch battery. This is due, partially, to the unavailability of a fuse heavy enough to withstand the stress of winching, and it also prevents weak spots in the winch wiring harness. It is typically recommended that a dedicated winch battery be used in a vehicle to prevent the winch from wearing the vehicle's battery down to the point that it will not start the vehicle's engine after winching. Even when allowing the engine to run while winching, the battery is often taxed to the point that it will no longer support the ignition requirements of the vehicle and the engine will stall.
When searching for a winch battery, it is typically advised by many winch manufacturers that a deep-cycle, marine-type battery be used. This will provide a very durable battery capable of extended winching without draining the charge. No matter which manufacturer's battery is used, the top post is the only recommended style of battery that should be used as a winch battery. This is because the thin metal strips that connect the battery's charging elements to the side post attachment points will often burn through under the load of a winch.
While the winch battery can be wired into the vehicle's charging system to recharge the battery while driving, a disconnect switch should typically be wired into the system to disconnect the winch power source from the rest of the charging system when using the winch. By isolating the winch battery from the primary vehicle battery, the vehicle can be allowed to idle while winching. This can be done to allow the vehicle's safety lights or emergency radio to be operated while winching, thereby eliminating a potential dangerous situation while winching in the dark.