View Full Version : Installing another Battery

05-25-2006, 10:25 PM
I know this has been covered a lot, I remember someone posting a wiring diagram somewhere, but I can't find it. Can someone point me in the right direction?

I have been talking about putting in another battery since last fall, but have yet to get around to it. After today, I will not go out again without it. About half an hour into the day, I seen my volt gauge was reading 11 volts. And then I put my wake plate up, and the radio shut off, then my perfect pass went dim and started to beep till it completely shut off, then the engine lost all of its power and eventually killed. So there I am drifting down the river @ 3mph, no boat in sight, heading right for a wall of rocks. I seen my boat flash in front of my eyes. My friends tried to push us away from the rocks. But it was not working. We seen a jet ski right when I though that all hope was lost, and we flagged him down, and he pulled us in. Not so much as a scratch on the boat. I went home feeling like an idiot. I could have at least threw a jumper pack in until I got another battery wired.

I took the boat over to the dealer, and they ordered a new alternator. It never fails, A holiday comes up, and my boat goes in the shop. I asked him about wiring in another battery, and he said something about a switch that lets you charge just one battery at a time or both. Do I need this? Or can I just wire up both batteries together and be done with it?

05-26-2006, 12:22 AM
I just got done installing my second battery today. I used a Perko switch and in my opinion it's definitely the way to go. Get the 4 position switch that lets you select either battery, both, or completely cut the batteries off. Wiring isn't that difficult. The worst of it is trying to make it look clean since the 2 guage wire you'll want to use doesn't like to bend that much. Just mount your second battery and use the diagram that comes with the switch it's pretty straight forward. All three of your positive connections will go to the switch (2 from the battery and the third that goes through the floor and back to the motor). Connect the negative lead from the motor to one battery and then run a jumper wire that connects the negative from battery one to the negative on battery two.

The only thing left is to hook up the wires from the accessories. That will depend on what all you're running. I've got 2 amps for my stereo and decided to hook them up on the spare battery. I chose to run the wires for the factory accessories which are connected to the breaker near the battery to the main battery. Doing it that way will still run the factory stereo from the main battery, but the draw won't be nearly as high as the two amps I'm running and I believe the bilge pump is wired in to this loop too which was why I made that decision.

If you want to do it the simple way, you could always just mount a second battery in a box next to the factory one. Keep a wrench handy and if your battery goes dead, just swap the connectors to the second battery. The downside is that you won't be able to charge the spare battery from the engine.

05-26-2006, 10:43 PM
Lots of information out there. Check at wakeworld, there are some drawings posted. Everyone has a theory about batteries, isolators, etc. I went with the manual option (perko), like lowdrag. Did the wiring like the perko instructions suggested. I also used a distribution block with one output to the accessories switch, one to the amp, and the main one out to the engine. Works fine.
I'd recommend reading up on batteries some. You don't want to parallel a charged battery with a drained one. Very high current that can melt wires. Not good especially with hydrogen gas present. A friend did this on his RV. A lot of people use isolators to avoid dealing with the above.
Click on my signature to check my setup. It took me a couple of hours once I had all the parts. I bought the cables, connectors, etc. from darvex.com. Good products at reasonable price. The second battery is the same type as the original (same charge/discharge characteristics). Good luck.

05-30-2006, 09:56 AM
Ok.. i have 2 batteries on my 02 LSV
I got something called a "COMBINER 50" from our favorite boating store West Marine (can use web too) What its purpose is... is to allow you to charge 2 batteries in parallel but only allows draw from one. This is useful only if you want one battery for accessories ie stereo/amp/my ballast pump switches are on there too/tower lights/anything not related to the dash/engine. This way i have one starting battery and one accessory battery. they both charge off the alternator (or charger in the garage) with the starting battery getting the charge first. and allows discharge separately (ie if the stereo gets left on too long or something else i can still start the boat and then subsequently charge the low battery)
Sounds like the perko switch/2nd battery would have done you no good due to the bad ALT maybe got you a little further. The perko switch is good if you want 2 batteries avail for starting (1/2/both/OFF) but i just wired my stereo power -(its currently hooked to your dash always hot power lead) and moved it to a place where all my access attach to the 2nd battery otherwise stereo left on = dead starting battery.
this has worked for 3 years and never had a dead starting battery-
COMBINER 50 - west marine.