Second battery in a Merc powered Islandia

[Dr Honda]

Honestly... this was a very simple upgrade. In a few boats I've done... the biggest issue is finding a good spot for the second battery. But... in the Merc islandia... there was already a big spot for it... right next to the main battery. Also... there was a nice stringer to mount the battery box to.

The box I used was a basic $10 box from Advance Auto. It's attached to the floor with a couple straps, and stainless screws. Then the box sits on top, and is held in place with a 2" Nylon strap.


The "Electrical part wasn't bad either. basically... I unbolted the old single switch... and replaced it with a double. Then... there was one main power cable added to feed from the positive of "Battery 2". Then... then ground of batt 2 goes to the ground of batt 1.

Because of the location of the switch, to the battery... you only need about a 3' power cable for Batt 2

The switch is a Guest #2111. The nice thing about this switch, is that it "Makes" the connection, before "Breaking" the last connection. Because of that... you can switch between the batteries, while the engine is running, without an issue.

Right now... if I want to make sure the battery is charged... I just set the switch to both, or the battery I want to use. BUT... the merc 240efi electrical system has two separate 20a circuits. When I get a little time... I will probably split it, so they both charge, regardless of the switch position.

It will be nice to not worry about running the radio too long, while sitting out on the water.


Here's some pics.

 

[martinez_0n]

KODr. Honda , I recently purchased the exact Guest switch as the one you used. I have a few questions on how to install . on the back I see the three bolts , which two will be a direct replacement from my old switch .

The battery 2 bolt is new and I know I will have to run a direct red power cable to the new batt 2. Now on to the negative cables, i read on your post that you can connect the negative from your batt 1 to the new batt 2 and that's the end of it ?

In the kit I received two red cables two negative cables and a jump box with two bolts all cable are the same length.

I will have to purchase a longer power cable due to my battery being on the other side of the motor . why two of each and also where does the jump box come into play ?

Any help would be greatly appreciated ..

Thanks Jose

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[Dr Honda]

Sorry I missed this. It was a older thread, and I just wasn't looking for it.


I'm not sure what you mean about a "Jump box." Post up some pics, and I may have an answer.


But yes.... the positive wires from the batteries go to the bolts #1 and #2 on the switch. The negatives can just be tired together. BUT... since you batteries are on the opposite sides of the engine compartment... you can just run the ground (negative) wire, from the second battery to the engine block.