Battery switch DIY?

Hey guys, looking into installing a second battery here pretty soon. Was looking at buying a battery switch wanting to see what you guys run. I have read a little about them and want to make sure I connect everything right, I've read that if you get the wrong type or have both batteries turned on for ex 1+2 it can cause damage to the alternator. Looking for recommendations on the better switches to buy and also install advice. Im running a 03 Launch SSV with indmar GM small block EFI. Thanks in advance, Matt.

I know people are tired of hearing this, but do a search. There are several good threads on this forum that beat this subject to death. Lots of opinions and there's no right answer.

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Originally Posted by Meyeronfire

Hey guys, looking into installing a second battery here pretty soon. Was looking at buying a battery switch wanting to see what you guys run. I have read a little about them and want to make sure I connect everything right, I've read that if you get the wrong type or have both batteries turned on for ex 1+2 it can cause damage to the alternator. Looking for recommendations on the better switches to buy and also install advice. Im running a 03 Launch SSV with indmar GM small block EFI. Thanks in advance, Matt.

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I bought one from Supra (SC) on my 2007. It's what the factory is using the newer boats.

Not that it's the best one, but I have a buddy that was helping me install new ballasts last spring. He has a connection and that is what we put in after the ballast project was complete.

On the Supra Site, there is a dowloads page.
http://www.supraboats.com/downloads/...wners_2013.pdf
Page 59 of 92 is how it was wired.

Mark

Matt,

There are a lot of correct ways to do a dual battery setup, and equally as many incorrect ways. The size (total Ah) of the house bank, combined current draw of the house loads (stereo and other accessory loads) and how the system intends to be used, will all influence the type of switch and how best to configure it. There are 3 basic routes: completely passive, passive/manual and completely manual.

IIRC, what comes OEM is a manual setup with a traditional OFF/1/BOTH/2 dual battery switch. This sounds like what you are after. Its a very easy setup to wire and very effective as long as you remember to flip the switch as needed.

The 3 most popular switches are made by Perko, Guest and Blue Sea. They all function the same, but the Perko is by far the lowest in quality of the 3. The plastic is brittle, the studs are smaller and shorter, the cables can only enter and exit at the bottom of the switch which really creates a bottle neck. Its also very shallow, leaving little room for multiple cables behind it.

I prefer the Blue Sea switch. larger deeper studs deeper mounting, flush-mount option, cables can enter and exit from all 4 sides.

I added my second battery before I discovered the forum. I ran a search, and am glad to see I did it as several others have done it. With teenagers and a non mechanical wife, I did not even consider the mechanical switch, and went fully automatic. If you forget to switch the mechanical, you loose the benefit of having an isolated battery to get home. If my automatic solenoid fails, the worst that happens is the radio quits...but we still get home.

The boat is used regularly in the summer, with a maintainer when not in use, so I saw no benefit for adding a shutoff switch. In the winter the batteries come out of the boat to maintain them and keep them warmer. If the boat sat for more than a month with no power for the maintainer, the manual shutoff would make sense. Otherwise it's just one more switch to remember.

I agree with what cjd posted, the auto system is a great alternative from the normal manual switches. It takes a few more steps to install, but the price is about the same and you never have to worry about switching anything over. Just uses an isolator relay rather than a manual switch. If you head this route, pm me and I can give some more information.

One disadvantage to eliminating the dual-bank switch is the loss of an emergency cranking bank if the primary battery takes a poo when out on the water.

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Originally Posted by Wylietunes

One disadvantage to eliminating the dual-bank switch is the loss of an emergency cranking bank if the primary battery takes a poo when out on the water.

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Actually, there is a connection to add that. All that is needed is a wire to the dash for a button to directly engage the solenoid. Of course, in the unlikely event of a solenoid failure, it is only a 1 minute job to manually connect the battery cables together at the solenoid for the start. You would likely know of the solenoid failure ahead of time, as the accessory battery would not be charging and would die.

But, if it is ever an issue, I am not opposed to adding the manual switch as a backup. In fact, it comes with the battery isolator kit.

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Originally Posted by CJD

Actually, there is a connection to add that. All that is needed is a wire to the dash for a button to directly engage the solenoid. Of course, in the unlikely event of a solenoid failure, it is only a 1 minute job to manually connect the battery cables together at the solenoid for the start. You would likely know of the solenoid failure ahead of time, as the accessory battery would not be charging and would die.

But, if it is ever an issue, I am not opposed to adding the manual switch as a backup. In fact, it comes with the battery isolator kit.

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Yes, manually engaging the solenoid with a switch will combine the battery banks, but a traditional dual-bank switch allows you to use only the hose bank as a backup starting battery. When batteries are combined, as in having the solenoid energized, the batteries will want to equalize. On some cases, this can seriously pull down the reserve battery.

Theres no one size fits all battery setup. Each has pro and cons and will need to be taken into consideration.

When I redo my stereo system this sping, i will probably swap out my switch and relay.
I want the starting battery to be separate from the stereo batteries.

Mark

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