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Author Topic:   Determining Boat Electrical System to be 12-Volt or 24-Volt
97dauntless17 posted 06-24-2015 12:22 PM ET (US)   Profile for 97dauntless17   Send Email to 97dauntless17  
My Outrage 19 has two 12-Volt batteries in the console. Is this a 12-Volt system, or a 24-Volt system? I'm puzzled. Trying to buy an onboard charger and I can't understand why there are two batteries and no trolling motor. Any guidance would be greatly appreciated. I also need to buy another bait well pump and don't know if I need a 12-Volt or 24-Volt pump. Thanks in advance.
boatdryver posted 06-24-2015 04:13 PM ET (US)     Profile for boatdryver  Send Email to boatdryver     
Any boat that small [i.e., a Boston Whaler 19-foot boat] is a 12-Volt boat.

The reason for dual batteries is to allow one to drift fish all day with, for example, the baitwell pump, stereo, and fish finder running for 12phours 20-miles offshore, and then, in the dark, have one battery unused all day, fully charged, and eager to start the motor to get home.

My 200 Dauntless has the factory setup for a trolling motor which I don't use. It has provisions for two extra group 27 12-Volt batteries just for the trolling motor.

Lots of owners without baitwells and other DC accessories chose to have a two battery setup for redundancy.


contender posted 06-26-2015 09:47 PM ET (US)     Profile for contender  Send Email to contender     
My truck has two batteries from the factory. Depending on the amount of electronics and lights you use, two batteries would be better. I use to have one battery on my Contender 25, put in a second battery. Now the engine turns over better and faster. My Contender can handle the space and extra weight some boats may have a problem with this.
jimh posted 06-27-2015 07:34 AM ET (US)     Profile for jimh  Send Email to jimh     
There is no good method to determine the wiring of two batteries just on the basis of the number of batteries being two. Electrical wiring can be--and is--very often quite variable from boat to boat, and the only way to determine how a particular boat is wired is by careful inspection and tracing of the wiring and circuitry.

The reason I have rigged my boat with two batteries: I cannot easily start the boat engine without a battery. Because of that, I have rigged the boat with two batteries, each capable of starting the engine by themselves.

Most DC electrical systems on small boats are 12-Volt systems. Higher DC voltage is generally only used on a small boat for very powerful electric motor auxiliary power, such as an electric trolling motor.

jimh posted 06-28-2015 08:38 AM ET (US)     Profile for jimh  Send Email to jimh     
A secondary reason for installing and rigging and wiring two batteries on my boat: to separate the electrical loads into two groups and keep them isolated. The outboard engine is wired as a load to one of the batteries. The rest of the boat electronics and electrical loads are wired as loads to the second battery. The two are kept separate so that voltage fluctuations during engine cranking do not affect electronics.
jimh posted 06-28-2015 09:00 AM ET (US)     Profile for jimh  Send Email to jimh     
When replacing an electrical device on a boat, here are two methods to determine if the device is intended to be operated by 12-Volts or 24-Volts:

--make a close visual inspection of the device, looking for an identification label that specifies the voltage and current needed; devices are typically clearly marked with the operating voltage and current they are designed for;

--after removing the original device, connect a voltmeter to the circuit that was supplying electrical power for the device; measure the voltage provided from the boat electrical system to the device.

jimh posted 06-30-2015 05:42 PM ET (US)     Profile for jimh  Send Email to jimh     
97DAUNTLESS17--Are you following this discussion?
deepwater posted 07-01-2015 01:05 AM ET (US)     Profile for deepwater  Send Email to deepwater     
if you want to know if your system is 12 or 24-Volt look at how the cables are attached--neg to neg and pos to pos it is 12-Volt.

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