Wiring 2 Batteries w/Switch

dcunninghamjr · #1 05-30-2005, 06:55 PM

I just recently bought my first boat after doing a ton of research. After reading discussion forums for months I settled on a 1978 SF20.

Anyway, I am in the process of re-wiring the electronics and could use some help. I bought a battery switch (1, 2 or both) which I would like to use to wire my engine to 1 battery and my electronics to the second. Any recommendations on how to configure the wires?

A buddy of mine suggested I forget the battery switch and link the batteries in parallel. Not sure how I feel about this approach.

Thanks in advance...

sailcat · #2 05-30-2005, 08:31 PM

DJC, I use 2 batteries and switch on my 20. I don't seperate my motor from the electronics, and usually run both batteries at the same time. Never had a problem with the charging system. Plus if one battery goes bad you still have the option to switch to the good one.

warthog5 · #3 05-31-2005, 12:09 PM

Running in Both or batteries in parallel is asking for a problem.
If one battery has a short in one cell, it will pull the other battery down to try and equilize the 2 batteries.
So the bottom line is that backup battery will do you no good,as you will have 2 dead batteries.

Only use "Both" on the switch for an emergency.

sailcat · #4 05-31-2005, 03:54 PM

Warthog, I guess the key to this would be maintenance. I don't go out unless I've charged both batteries, if one is not charging correctly then it gets replaced. I've never had a problem (knock on wood). But your correct, if one battery is bad it will drag the other down.

dcunninghamjr · #5 05-31-2005, 04:58 PM

What do you guys think about this approach?

http://64.233.161.104/search?q=cache...&hl=en&start=1

warthog5 · #6 05-31-2005, 05:07 PM

DJC There are a couple of thing's I don't like about that setup. While I do have a similar setup in my little Scout.
Where the power comes off for the House curcuit. This will cause your electronic's to shut down when you crank the motor.
You must remember to turn the switch. Run out on one battery and then switch to the other battery to run in on.

warthog5 · #7 05-31-2005, 04:59 PM

There are plenty of wiring digram's online if you look.
Thke a look at the manufactures of marine battery switch's.
http://www.jerrylabella.com/ship_shape2.htm
http://www.cmsquick.com/tech_03_batsel.html

I'm using 2 of the Newmar Battery Integrator's. This will be setup with 2 outboards and 4 batteries. 2 dedicated starting batteries and 2 House batteries in parell.

gw204 · #8 05-31-2005, 12:00 PM

Here's what I did:

http://cablespeed.com/%7Ebriandm/projects/project1.htm

And it's worked quite well. [img]/images/graemlins/smile.gif[/img]

SC204 · #9 06-08-2005, 06:12 AM

anybody have any experience with an automatic charging relay?

dcunninghamjr · #10 06-08-2005, 08:58 PM

OK - batteries wired. Took the boat out this weekend and everything was perfect.

Tonight I tried to wire in a stereo. There's a breaker in the electronics box where the previous owner wired his VHF and stereo.

I connected my stereo to the breaker and powered on the stereo. It powered up but did not seem to get consistent power. When I looked at the fuse, it was glowing orange. Do you think a stronger fuse will fix the problem?

I connected the stereo directly to a spare battery and it worked without a problem. It's the introduction of the fuse/breaker plate when the problem occurs.

A little help!?!?!?