Bluewater 1-2-BOTH Battery Switch


(2 customer reviews)

9800-007-11 Battery Switch

Single Pole, Double Throw

1 Input, 2 Outputs

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Bluewater 1-2-BOTH Battery Switch
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Product Description

Bluewater 9800-007-11 Battery Switch

Our Bluewater 9800-007-11 battery switch has 2 inputs and 1 output.  PLUS, it has the built-in capability to parallel both outputs.  It’s called a 1-2-BOTH switch (and it has an OFF position, of course).

This would commonly be used on a boat with two batteries: a “start” and a “house”.  It would normally be used when you do not have an Automatic Charging Relay installed and prefer to manually control which battery is charged by your engine’s alternator.

Let’s run through how our 1-2-BOTH Battery Switch would work:

Let’s say you have:

  • ‘Start’ Battery is tied to lug “1”
  • ‘House’ Battery is tied to lug “2”
  • And your engine and lead to your fuse panel is tied to lug ‘OUTPUT’

Then, in each position you would get:

  • OFF – Nothing.  Both batteries are isolated
  • POS 1 – The house battery is isolated, and everything is running off the start battery: house loads, engine cranking, and engine charging
  • POS 2 – The start battery is isolated, and everything is running off the house battery: house loads, engine cranking, and engine charging
  • BOTH – The house and start battery are combined. The engine is charging both batteries while running, and the house loads are draining both batteries

How does this look in practice?

You’ve been storing the boat in the OFF position so the batteries don’t get drained.  You get to the ramp, turn your Bluewater 1-2-BOTH battery switch to “1” position, and crank the engine.  Once you push off, you rotate the battery switch to BOTH, so that the alternator is charging both batteries as you cruise around.

Soon you get to your favorite fishing spot and shutoff the engine… you’d want to preserve the start battery for starting so you turn the 1-2-BOTH battery switch to position “2”.  Now the stereo and aerator (or other loads) are only drawing down your deep cycle house battery.

While you’ve been fishing, if the house battery has been drained too far down to start the engine, you have a nice, full start battery waiting… so just turn the battery switch to position 1 and head home.

What are the drawbacks?

Well, the downside is you have to remember to manually change the Bluewater 1-2-BOTH battery switch depending on the charge/discharge state you’re currently in.  Also, if both batteries are paralleled, a severely drained battery can suck the charge out of the good one to the point that neither can crank the engine.  See our Blue Sea 6011 with ACR setup for a more automated – hands off – option.


1-2-BOTH Boat Battery Switch Specs:

  • Type: SPDT
  • Positions: 4 – (1/2/BOTH/OFF)
  • Inputs: 2
  • Outputs: 1
  • Batt Combine: Yes
  • Continuous Current Rating: 300A
  • Intermittent Current Rating: 500A
  • Cranking Current Rating (30s): 900A
  • Stud Size: 3/8″

Marine Grade Battery Switch

Our Bluewater 9800-007-11 battery switch is made for the marine environment with tin-plated copper contacts and studs inside and out.  We love the way this switch has a physical snap as it locks into place, so there’s no question if it’s in position or not.

The 7/8″ Stud length also allows for the multiple wire lug connections common on boats.  For example, you may like desire to run both your engine feed cable, and the conductor feeding your boat’s switch panel from the same output stud.

Make Before Break

NOTE: Our Bluewater 1-2-BOTH boat battery switch has make-before-break contacts.  This means as you rotate from 1 to 2 to BOTH, the next position is closed before the previous position opens.  This allows for safe switching between 1, 2 and both while your engine is running without damage.  Never rotate through position OFF though with the motor running; it may damage the engine.  So always rotate through BOTH while changing from position 1 to 2 while the engine is running.

2 reviews for Bluewater 1-2-BOTH Battery Switch

  1. James Quiett

    The switches came nicely packed and secure. Easy to replace the old ones. Easy to find exactly what I needed.

  2. Kenneth Paul (verified owner)

    Very good quality heavy duty. Awesome site they have wiring schematics FREE.

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