Battery Switches for Safety & Practicality
Depending on the size of your boat, a battery switch can mean different things. On small boats, it can serve as a master switch. It shuts off all electronics wired in after the switch. On larger boats, there might be multiple on and off switches or switches that allow you to pick between battery banks.
Despite the difference in boat sizes and levels of electronics, boat battery switches protect boats in many ways. By removing all potential power draws, battery switches protect your boat from excessive battery drain. In removing all power, a battery switch can also remove electrical fire hazards. Another important safety benefit is being able to cut off electrical power while doing maintenance or troubleshooting a boat’s entire electrical system.
Besides being a critical safety feature, boat switches are very practical for everyday use. In many different scenarios, being able to only draw power from one bank of batteries while you preserve battery life in the others, gives you peace of mind that your starting batteries will be just as charged as you left them.
As described previously, battery switches can make a boat much safer to leave unattended. There are still things to consider with marine battery switches. Whenever you’re installing or working on a battery switch, be sure to manually disconnect your battery. Even the most skilled electricians can make mistakes, and removing the power source can stop those mistakes from causing an injury.
Battery Switches With Alternator Field Disconnect
Another thing to consider for the safety of your equipment is getting a switch with an alternator field disconnect. We at Boat Outfitters have the included alternator field disconnect included with both our Heavy Duty Battery Disconnect Switch and Heavy Duty Battery Selector Switch. When your motor is running and the battery selector is set to one or both batteries, your alternator’s output is going into the battery or batteries. If you were to accidentally turn off your battery switch, the voltage in the motor would skyrocket.
This excess voltage can cause all sorts of damage to your electrical system, typically frying the diodes in your outboard. Depending on how you’re mounting your battery switches and who might be using your boat, a switch with an alternator field disconnect may be something to consider.
How Battery Switches Work
Battery switches are simple in terms of construction and function. Most marine switches consist of a heavy-duty plastic frame and stainless mounting hardware. These materials will not corrode and they provide the strength needed to protect the internal components of the switch.
The internal conductive materials of the switches are typically made of tin-plated copper. This material is chosen to fight the corrosive habitat of boats and to properly conduct electricity as needed. By rotating the switch from position to position, certain circuit connections are opened or closed depending on what setting the switch dial is on.
Boat Battery Switch Configurations
There are many different configurations of batteries and switches depending on the size and use of your vessel. Generally, battery banks are lumped into two categories: “house” and “starting.” The starting batteries on your boat should only serve one purpose, starting your motors. The house bank powers everything else.
Depending on the size and needs of your vessel, the house bank can consist of one battery to power some simple electronics, or multiple batteries to serve your day-to-day electrical needs on your live-aboard boat.
This division is incredibly useful when you decide to shut off your batteries or disconnect from shore power. Instead of worrying if you will have enough power left to start your motors, you can choose to run only your house bank. This allows you to drain one bank while knowing you have preserved enough power to start your motor or motors when you need to recharge.
Starting batteries are also built differently than house batteries. A starting battery is designed to deliver a quick short burst of high energy when needed to start the engine or engines. House batteries are typically deep cycle. They are not designed to deliver as much instant energy but instead deliver long-term consistent energy.
Boat Battery Switch Mounting Considerations
Where you mount your battery switch or switches requires considering a few factors. Surface mounting a switch on the outside of the vessel can provide ease of access, but no protection from the weather. If at all possible, it’s important to keep your switches out of the elements. They are built to stand up to the marine climate but will last longer protected from it.
On most boats, switches are most commonly mounted inside the console. This consolidates them in one area for ease of operation and is easily accessed by the captain. It is important to keep your switch or switches easily accessed in the event of an emergency. Being able to cut electrical power quickly can make the difference between just smoke and an all-out fire. Some switches come in their own mounting boxes, offering both protection and accessibility. Be careful to not make your switch too accessible! Mounting your switch in a high-traffic area could lead to disaster.
Besides ease of access and weather, consider how far you mount your switch from your batteries. When running long electrical cables, be sure to consider voltage drop. There are calculators available online, but as a general rule, the longer the wire is, the more a circuit will suffer from voltage drop. In other words, your battery switches should be as close to your batteries as reasonably possible.
Now that you have picked the perfect spot for your battery switch, be sure to mount it properly. Battery switches are typically holding up heavy gauge battery cables, so through-bolt them if at all possible. Be sure to seal any holes you make on your boat, as even a little bit of moisture can cause delamination and rot. When mounting on top of the gelcoat, be sure to counter-sink your mounting holes before tightening. This will help to avoid unattractive stress cracks on your gelcoat. Most importantly, be sure to use the proper high-quality stainless steel mounting hardware. Trying to save money by using non-marine-grade hardware will be costly in the long run.
Most of your electronics should be wired to a switch for all of the benefits previously described. There is however, one thing that should not is your bilge pump. Your bilge pump needs to be connected to power at all times. This will allow your bilge pump to kick on whenever the float switch turns it on, potentially keeping your boat from sinking. Of all the boats that sink, two-thirds of them sink while at the dock. A dead battery is better than a sunken boat.
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