Question about the wiring of a 9.9 johnson outboard with a battery switch

May 16, 2024
18
o'Day 23 Muskegon, MI
I have an 1979 oday 23 that has the 9.9 johnson outboard. I have two batteries in the battery compartment and the previous owner simply swapped terminals if the other battery was needed for starting, etc. I am installing a battery switch (1,2, both, off). I noticed that the there are two sets of wires (red and back sheathed together) that appear to go to the outboard. Originally, both sets were hooked up to the appropriate terminal of the battery that was in use. This is my firsts outboard, so I am still learning. I owned a sterndrive before this, and it's setup had one positive and one negative. The outboard schematics I had seen online also seem to show a single positive and negative. Currently I am planning to hook it up with the 2 positives to the Feeder terminal and then a negative to each of the batteries. This configuration seems like it should work since it will be replicating the previous setup.

My questions:
1. Is there a reason there are 2 sets of these wires and not just one?
2. And is there a certain way to different way I should connect this using the switch?
 
Mar 6, 2008
1,290
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
It is possible that the previous owner added the second set. Look into the engine and see where these cables are connected. Disconnect one set.
Connect the negative of the batteries to each other and to the black cable connected to the engine. Connect the positive of the engine to the C or common terminal of the switch. Then each positive lug of the battery Connect to switch lug 1 and 2.
 
Sep 24, 2018
3,258
Catalina 30 MKIII Chicago
I'm not really following you but I had the exact setup that you are trying to achieve. There is a black, two conductor, 10awg cable that should come from the outboard. The end should have (or had) ring terminals. One should have red heat shrink to indicate positive. This positive lead should go to the "output" of your battery switch along. Your boat's electrical system should also be connected to this terminal. This allows you to start off of or charge either battery. The other two terminals of the switches go to the positives on the batteries. All negative leads, including the batteries, should be connected together
 
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May 16, 2024
18
o'Day 23 Muskegon, MI
I'm not really following you but I had the exact setup that you are trying to achieve. There is a black, two conductor, 10awg cable that should come from the outboard. The end should have (or had) ring terminals. One should have red heat shrink to indicate positive. This positive lead should go to the "output" of your battery switch along. Your boat's electrical system should also be connected to this terminal. This allows you to start off of or charge either battery. The other two terminals of the switches go to the positives on the batteries. All negative leads, including the batteries, should be connected together
Thank you for the responses. I think I discovered the answer while typing this up.

I have not yet gotten back onto the boat to trace the wires, but they did appear to go towards the motor. There are two sets of the wires that you described, each set has an identified positive wire and a negative wire with ring terminals. Originally, both negatives were on the negative battery terminal and both positives were on the positve battery terminal with the single battery hooked up. I believe have it wired correctly based on the way it worked previously, but I am just confused on the function of this second set of wires. Last year, I did confirm that the outboard did appear to be charging the battery (slightly) while it was running. After typing the previous sentence, I looked online and found that the charging system does have its own set of wires (including the boot that appears to come with the kit). So with that, I would presume that both positive rings will go to the common (feeder) post of the switch while the negative ones to the ground of the battery.
 
May 16, 2024
18
o'Day 23 Muskegon, MI
It is possible that the previous owner added the second set. Look into the engine and see where these cables are connected. Disconnect one set.
Connect the negative of the batteries to each other and to the black cable connected to the engine. Connect the positive of the engine to the C or common terminal of the switch. Then each positive lug of the battery Connect to switch lug 1 and 2.
Thank you for your response. I believe that the second set is for the charging system on the outboard. I did confirm that the motor was charging the battery that was connected.
 
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Sep 24, 2018
3,258
Catalina 30 MKIII Chicago
There should only be one set of wires between the outboard and the battery/switch. Don't expect much charging from the outboard, especially on a sailboat. You're also dumping unregulated power into your batteries. I've seen mine reach 16-18v at WOT
 
May 16, 2024
18
o'Day 23 Muskegon, MI
There should only be one set of wires between the outboard and the battery/switch. Don't expect much charging from the outboard, especially on a sailboat. You're also dumping unregulated power into your batteries. I've seen mine reach 16-18v at WOT
When I get back into the boat (it's snowing again in Michigan) I will trace those wires and see where they go.
 
May 16, 2024
18
o'Day 23 Muskegon, MI
There should only be one set of wires between the outboard and the battery/switch. Don't expect much charging from the outboard, especially on a sailboat. You're also dumping unregulated power into your batteries. I've seen mine reach 16-18v at WOT
Thank you for all the input.

I was able to get onto the boat yesterday. There is what appears to be a solenoid (currently in use) in the battery compartment that is connected and in use by the remote starting system (which I just realized that I did not mention that previously and that very likely makes a difference). One of the positive wires comes from that solenoid and one from the motor, then were connected together at the battery (prior setup). Since both were connected to the single positive terminal, I figure that reconnecting these two to the "feeder" would still work. I tested it and both batteries will turn over the motor (no fuses/breakers popped or sparks). I still need to confirm the charging in this setup.

Note: That solenoid has only one large terminal, and not two like I am used to seeing in other applications. I tried finding this online, but I have had no luck. I have found kits that have the same style box, but the solenoid in those kits look like the traditional 2 large terminals. Is it possible this is something other than a solenoid?
 
Last edited:
Jan 8, 2025
175
Compac 16 Pensacola, FL
Black wire direct to one battery negative; a jumper wire to the other battery negative. Do not jump the two positive battery poles. Red wire from motor to the central terminal (OFF) of the switch. Red wires from the positive poles of the batteries to the 1 and 2 terminals. This is the basic setup. I have no experience with a remote start system but assume that the red wire from the solenoid that was attached to one of the batteries would attach to the OFF terminal (which is energized by either the 1 or 2 terminals).