View Full Version : How many batteries do I need?

08-09-2005, 04:43 AM
I have just purchased an 18ímodified V hull aluminum boat with a 75 hp Merc and am in the process of installing my electronics, fish finder/GPS, VHS radio, two electric Scotty downriggers, and a black box. My question is: The battery that came with the boat is a cranking battery, not a deep cycle. It runs the nav lights, live well, bilge pump and power trim. Should I purchase a deep cycle battery to run the electronics and install a charging module so that the motor will charge both batteries? The manual for the fish finder indicates I should keep the wiring connections away from the motor cranking battery for best results.
Most of my fishing is confined to lake trolling and at this point I think I can get away with using a trolling plate, rather that a kicker motor, but wonít know for sure until I get the GPS and paddle wheel hooked up.
Any advice would be greatly appreciated.

08-09-2005, 06:21 AM
Install a couple of fuse blocks and you can run all your electronics off your cranking battery.

08-10-2005, 05:55 PM
Thanks Hinrid

08-10-2005, 07:35 PM
A second thought. Have you ever been at the dock waiting to launch while the ski boat ahead of you, is trying to figure out how to jump his boat, so he can get it out of the way. Have you read posts on this board about marine electronics sapping the charge out of a battery, even though everything was supposed to be turned off. Have you ever pulled up to a floating dock that someone stopped to have lunch at, and now their boat needs a jump or a tow. Have you ever..... well you get the idea. If you have room for two batteries do your self a favor and mount both with a perko switch. You'll do your self a favor. There is already a thread on the first or second page, as how to proceed with wiring two batteries. Might take a look. ;)

Sorry, I'm not trying to be pushy but if you can avoid trouble on the water, you're really far ahead of the game. Hinrid is right on, about the fuse block, easy to check and keeps all of your electronics safe.

08-11-2005, 07:46 AM
I know what you mean, MetalMouth. Recently, I had to wait (20 min.) for a guy that put his boat in the water, parked his trailer, and then realized he hadn't charged his battery since last season. And to top it off, he walked SLOWLY to his truck to take out his truck battery and put that into his boat (instead of pulling his boat out to work on it). All of this time, no one could launch their boats. >:( >:( >:( So Irish, I would definately look into getting another battery for your boat like MetalMouth said. No, not because I think you would do what the idiot at the ramp did to me, but for your own state of mind while out on the water. If your one battery goes dead, you can make it back to the launch ramp safely. Trust me on this one, I'm talking from experience. I recently broke down on the Sac River, and had to get a tow from the sheriff boat-lights and all!! (a fuel problem, not a battery problem). See you on the water, and good luck with your new boat!! ;D

08-11-2005, 01:51 PM
Doubles are common with perkos these days...

everything adds up and everyone here including yours truly has seen a dead boat battery at the wrong moment :P

I haven't tried these optimax's...I'm sure there are a few out here that will chime in with that one. ;)

08-11-2005, 05:51 PM
I have a main batt and one for my trolling motor and in between I have a battery isolater-easier than a switch it automatically figures out witch batt is low(under way or w/outboard on) and charges that one once the low one is charged it distributes the charge to the 2--before I got it I could troll for 1 day now the only limits are my gas

08-12-2005, 11:20 PM
I had a second battery and switch added to mine when I purchased it. I am just paranoid about the battery going dead and not having a backup since I like to listen to the vhf and run the gps/fishfinder and have electric downriggers.

08-13-2005, 03:23 AM
Thanks for the input guys. My first gut feeling was to add a gel deep cycle battery with a Perko switch to run the electronics. I'm not sure how much of a recharge I will get from the motor when spending a day trolling. I've been told about 80%. I think I'll get the second battery. Your points are well taken.
Thanks again for the input.

08-13-2005, 12:06 PM
The Perko switch will allow you to run everything off of either battery. It is like having jumper cables hard wired into your boat. Or you can run off of both batteries at the same time, but that is only recommended in emergencies because if one battery has more of a charge than another they will equalize. Depending on the difference between batteries the wires and switch can get pretty hot. I just finished installing a dual battery system with a Perko switch and a dual battery charger. Nothing like piece of mind while out on the water. I had the new cables made at Battery Bills they were very reasonable, and fast.