For any vehicle that needs to use two batteries where one battery is used for starting the engine. while the other is used to power auxiliary loads. This is a common situation in trucks. boats. RVs. police and rescue vehicles. and in ambulances or fire equipment. A selector switch allows use of the first battery. the second battery. or both batteries simultaneously. This provides back-up starting power in an emergency.

These switches combine the functions of Battery Selector and Master Disconnect Switches to give four battery power options:

Power cut off at the source
Power On. Battery 2
Power On. Battery 1
Power On. both Batteries

Battery selector switches provide a positive battery disconnect. which has many advantages:

It gives a reliable shutdown of power during maintenance
The version with the key protects against theft of the vehicle. when unattended
It helps protect against electrical fires. when the vehicle is not in use. and minimizes battery drain

Rating: 500A intermittent. 310A continuous. 6-36V DC Electrical ratings on UL labels are conservative. Electrical Ratings Labeled UL 707B
Use with either alternators or generators.
Make before break design permits operation through the three On positions with the engines running. Engines should always be shut down before turning to Off.

Heavy-Duty Construction Vaporproof. weather-. dust- and corrosion-resistant.
Durable. fracture-resistant high temperature plastic case. knob and insulator.
Switches conform to USCG section 183.410 for ignition protection.
Resistant to impact. and temperature extremes.
Heavy duty copper stud terminals. with brass hexnuts.
Can be surface mounted. or installed through a 3 5/16"" diameter hole in the panel.
Dimensions: Flange: 6"" (152.4mm) diameter. overall height 2 5/8"" (66.7mm).
Terminals: 3 copper studs. 3/8"" (9.5mm) diameter. Offsite info on Marine Power Generation Offsite info on Marine Dual Battery Wiring

Warning: Product may contain materials cautioned by California Proposition 65