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Battery Management solution for your Boat 

Smart Dual Battery Switch system

Why this is needed:

• You get in your boat and the battery is dead.

• You seem to have to replace your battery almost every year.

• You worry about getting caught on the lake not able to start the engine.

• You never know if your battery is fully charged.

• You have an A/B Combined Battery selector switch but do not know how to use it.

• You do not want to think about the batteries in you boat, you just want them to work right.

  • On large Boats they have banks of batteries and they isolate the Engine battery from the “House” batteries.  Most Pontoon boats do not have this. 
  • The Pontoon boat manufacturers are just now starting to install Battery Isolation and switch systems on their high-end, Tri-toon, big engine models. Previous models do not have this.

A little background information.

Most boats have but one battery. Hooked to this battery is the Engine and the electronics on the helm (Radio, lighting, etc). The battery is charged by the alternator on the engine. The popular belief would be that my alternator will charge my engine as much as needed for me to operate the boat. Well maybe, or maybe not. 

Here is a list of current Mercury Outboards and their alternator output:

40, 50, 60 Horsepower 18 Amp 226 watts output 

75, 90, 115 Horsepower 35 Amp 440 watts output

150 Horsepower 60 Amp 756 Watts output

250/300 Horsepower 115 Amp 1449 Watts output

350/400 Horsepower 70 Amp 882 Watts

          - At idle the Battery should be at 12.8-13.1 VDC      - To charge it need to receive about 14.5v at 1,500 RPM.

         - When going slowly around the lake on a “Sunset tour” you are doing about 1,000-1,500  RPM.

It takes 1500 - 2000 RPM, at a minimum, for the Alt to charge a battery and it would take some time (3-5 hours ) for the battery to get fully charged, provided the battery isn't sulfated, or otherwise compromised. 

   -  How often do you run your boat at that RPM or for that length of time?


The output of an alternator is usually expressed in amperes, which is essentially just the amount of current that the unit is capable of providing to all of the equipment that’s hooked into the electrical system. There’s a difference between an alternator’s amperage “rating” and the amount of current that it can provide at idle speeds. 

The term “alternator output” refers to two distinct, yet related, concepts. The first is the alternator output rating, which is the amount of current that a unit is capable of producing at a specific rotational speed. For instance, a 100A alternator has a “rated” output of 100A, which means that it is capable of providing 100A when the alternator shaft is rotating at 6,000 RPM.

The other thing that alternator output can refer to is the amount of current that a unit actually produces at any given time, which is a function of the physical capabilities of the alternator, the rotational speed of the input shaft, and the momentary demands of the electrical system.

 While maximum alternator output is dependent on the rotational speed of the input shaft, the actual output is load-dependent. That basically means that an alternator will never generate more current than is called for by the momentary demands of the electrical system.

This product is limited to Boat manufacturers. Currently not available to aftermarket customers.

What is needed in a Dual Battery system on a boat.