Marine Battery Switches

 

Boats running off of multiple batteries will utilize a battery switch to manage what parts of the boat pull from what battery as well as manage the charge among the batteries. If you are new to boating and need to either install or replace an existing battery switch, the following information will help you know which switch to buy and when you might need to buy one with the “AFD” (Alternator Field Disconnect) feature.

 

If you have room on your boat and are planning on running the radio, a fridge, lights etc. it is a good idea to have a seperate battery for these needs. These batteries are typically referred to as the house batteries. Having more than one battery is called a bank of batteries. The main battery in the bank is what will start the engine. A marine battery switch turns off and on loads to the batteries without reconnecting your wires each time you drain one battery. This is very important in keeping the battery that starts your engine fully charged while out on the water, especially if you have a lot of battery powered items on board your boat.

 

Which Battery Switch Do I Need?

 

There are a variety of battery switches on the market. Popular manufacturers of battery switches include, Blue Sea Systems, Perko, Guest and others. Most battery switches come with 4 positions, OFF, 1, 2, and All. When the battery switch is on OFF, that typically means you are either running the engine (the alternator is not charging your batteries) or you are docked and your batteries are being charged by of shore power. Position 1 is typically dedicated to the engine while 2 is for the house battery bank. The All position is useful if your starter battery is run down and you need more juice, but if you accidentally leave this postion on, you may end up with all dead batteries. Therefore, we recommend that you install an Add-A-Battery by Blue Sea Systems which automates the switching between batteries so you never run out of battery power. We also recommend purchasing a battery switch with and AFD (alternator field disconnect) if you do not have a battery isolator. The alternator field disconnect prevents voltage spikes to your regulator and alternator if the off position is selected momentarily while the engine is running.

 

Blue Sea Systems carries three versions of battery switches. The m-series battery switches are for 300 Amps continuous rating for outboards and small gasoline or diesel engines. The e-series battery switches are for 350 Amps continuous rating for inboard gasoline or diesel engines, and the HD-Series battery switches are for up to 600 Amps continuous rating for large diesel engines. There are various options for number of switches and AFD options per type.

 

While there are many battery switches to choose from, we hope that you are now able to narrow down your search. If you have further questions, please don’t hesitate to contact our experts.