Technical article from Blue Sea Systems
February 13, 2008
When installing a battery switch, ABYC guidelines call for consideration of these two factors:
- Minimize voltage drop between battery bank and load-voltage drop can lead to poor performance because of the decreased voltage level at the load.
- Install the switch in a location that it is readily accessible. If it is necessary to disconnect the battery from the load in an emergency, the operator should be able to do so at a location away from the most likely source of fire- the engine room.
ABYC 18.104.22.168.2 A battery switch shall be mounted in a readily accessible location as close as practicable to the battery.
Battery switch installation in small boats
In a small boat, a battery switch can usually be installed in a location that is both close to the battery bank and readily accessible. A traditional mechanical battery switch is a suitable choice for this application.
Battery switch installation in large boats
In a large boat (30 feet or greater), it may be difficult to install a battery switch in a location that is both close to the battery bank and readily accessible. With large boats, there are three common installation options:
- Option 1 - Remote battery switch. Install a remote battery switch near the battery bank to minimize the weight and cost of large wires over long distance. Install a control switch in a readily accessible and safe location. This option results in placing functions where they belong: high current switch close to battery bank, low current control in readily accessible location, and small diameter wire between them.
- Option 2 - Near battery bank. Install a mechanical battery switch near the battery bank. This installation will minimize voltage drop, but the switch will not be in a readily accessible location. On large boats, the battery switch is typically installed in the engine room. In case of a fire, going into the engine room to open the circuit could be dangerous.
- Option 3 - Readily accessible. Install a mechanical battery switch in a location that is readily accessible in an emergency. This option typically requires long runs of large diameter wire between switch and battery bank. Running 2/0 AWG wire just 10 feet from battery bank to a readily accessible location and back can cost (10+10) X $15/ft = $300.
See Technical Brief: Five Reasons to Use a Remote Battery Switch for a discussion of cost and weight savings associated with battery switch installation.
For large boats, Option 1 - Remote battery switch, results in cost and weight savings because there is:
- No need for long runs of large-diameter wire
- Increased safety because the control is moved away from the probable source of fire
The cost of installing a remote battery switch is often comparable to the cost of installing a mechanical battery switch in a readily accessible location when the cost of large diameter wire is considered.
Original article from Blue Sea Systems