need help with battery switch

[volstreet]

Hello, I have a 18ft pontoon with 2004 25hp merc. Used mostly for
fishing. I would like to intall a second battery to help with my depth finder
and downriggers. I am concidering a Perko. The instruction say run a ground
wire to the engine block. Isn't the black starting cable grounded? Can I use
it? and where does the red wire go? to the common? This should be simple,
or am i making it hard. All help appreciated.

 

[slvrwolf1]

Re: need help with battery switch

http://continuouswave.com/whaler/reference/dualBattery.html

I think this explains it better.

 

[slvrwolf1]

Re: need help with battery switch

you should have a switch with 3 terminals 2 positive and 1 common. connect the negative of the batteries with a black wire. Then run a red wire from positive port side batery to one positive terminal on switch. Run another wire from starboard side battery to other positive terminal on switch. Run red wire from common on switch to positive on engine. Also connect your fusebox or your positives to your Depth finder, radio, cb (etc..) to the common and connect the Negative of one of the batteries to the fuse box or the negatives on acessories. I hope this helps.

 

[volstreet]

Re: need help with battery switch

Thanks for the replies. I am still confused. the motor has two wires black and red for starting. Can I use these for the postive and negative connection to
the battery(black negative) and switch (red postive?

 

[slvrwolf1]

Re: need help with battery switch

sorry it took so long to get back to reply. I am at work and can only check in from time to time. You can use the black ( negative) wire to connect directly to battery negative from the engine but you have to also hook negative to negative on the batteries also. The positive (red) wire on the engine connects to the common terminal along with all your positive wires on your accessories.

 

[slvrwolf1]

Re: need help with battery switch

sorry it took so long to get back to reply. I am at work and can only check in from time to time. You can use the black ( negative) wire to connect directly to battery negative from the engine but you have to also hook negative to negative on the batteries also. The positive (red) wire on the engine connects to the common terminal along with all your positive wires on your accessories.

LOL I forgot to label those square things those are batteries in case you were wondering.

 

[Silvertip]

Re: need help with battery switch

The question I always ask when someone wants to add a battery switch, isolator, ACR, or any other "extra battery" device is how do you intend to charge the second battery? In most recreational boats adding a battery switch is not necessary and is even less necessary when you have a small engine like yours. Why? Just because your engine has a charging system does not mean it is capable of keeping up with the electrical demands. In my view, you don't need a switch, but you do need an on-board charger that you can plug in at the dock to get the house battery charged as quickly as possible. Deep cycle batteries should not sit in a discharged state. If you do install a switch, are you sure the method you use to install it, meets your specific needs and that you understand the versatility the switch provides. Using a switch the wrong way or installing it in a manner that doesn't meet your specific requirements means you went through a lot of trouble and expense only to create another problem. Battery switches are great devices but many folks don't use them correctly. The key ingredient here is your engine has a very small alternator. It simply can't keep a deep cycle battery topped off in a short run back to the dock.

 

[volstreet]

Re: need help with battery switch

Thanks for your reply I can see how it is done now. Even though the out from
alternator is small. I troll 3 or 4 hours with the main motor each outing, so
I get some charge back to the trolling battery . Thanks again for your help