11.0 battery wiring

mbefus

mbefus

.
Apr 21, 2024
15
S2 11.0A Muskegon, Michigan
New 1981 11.0a owner here. It appears that the PO made some changes to the battery wiring, but I’m hoping to confirm. Does anyone with original wiring have a photo of how it was wired? Or able to explain?

I had also hoped to find a complete wiring diagram…but looks like maybe they were never made public.

The thing I’m curious about is why the house battery positive is wired to the starter battery positive? (See photo)
 
D

dlochner

.
Jan 11, 2014
12,746
Sabre 362 113 Fair Haven, NY
The photo didn't make it.

This would put the batteries in parallel which has some advantages in terms of capacity and battery life.

Much has changed in the land of batteries and battery management since your boat was built. It is likely the PO tried something different. How well he did, no one knows.

Standard practice back in the day was to have the alternator output be connected to the starter. This ensured that whatever battery was used to start the engine would be charged and it reduced installation costs for builders and reduced warranty claims for engine manufacturer and boat builder.

The 2 batteries were separate and connected to a 1-2--Both switch. This article gives an excellent description of the pros and cons of that arrangement.

marinehowto.com

1/2/BOTH Switch Considerations

1/2/BOTH Battery Switch Considerations - Ever wonder how to make the 1/2/BOTH switch easier to use, let this article explain how to do that.
marinehowto.com
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
22,988
Catalina 34 224 Maple Bay, BC, Canada
Here's a basic wiring diagram. If you don't have a combiner, use the B on the switch.

Daves Battery Hookup.jpg
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,813
CAL 35 Cruiser #21 moored EVERETT WA
mbefus said:
The thing I’m curious about is why the house battery positive is wired to the starter battery positive? (See photo)
Click to expand
No photos in the post.

We can only guess at the reason the PO did the wiring. Electrical systems on boats follow a similar design. A charging source (in your case the alternator), is connected through a switch (or in the diagram by @Stu Jackson a combining relay and a switch) to the positives on both batteries (in parallel). This lets the alternator charge the batteries while generating power from the auxiliary.

Many 40 year old boats have had the electrical systems modified by owners. Some have been improved, others not so much. Rather than spending much time worrying about the way things were done in the 80's I would suggest you gather an understanding of today's system design and work towards upgrading your boats systems. You'll have a better system than designed in the 80's, you'll have access to modern parts, and you will get back on the water sailing sooner rather than later.

Here are a couple of links to good resource material.
marinehowto.com

Marine How To - DIY for Boaters - Marine How To

For DIY boaters in an attempt to try and keep the sport as affordable & safe as possible. How To articles for sailboats and powerboats.
marinehowto.com

Musings With Maine Sail

How-to's, photos, and general wisdom from our own Maine Sail, founder of MarineHowTo.com.
forums.sailboatowners.com
 
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