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New motor wiring to selector switch

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hsvbama
Deckhand

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Initially Posted - 06/27/2017 : 16:08:57

Just picked up a new Tohatsu 9.8 motor with electric start. Old motor was not hooked up. Been looking at the wiring diagram and would like to verify the proper hookup to the battery/selector switch. Looks like positive wire from the motor to the #2 switch terminal (only one battery for now) and negative wire to the common terminal on the switch?

Also, I have a battery maintainer/charger that I hook up directly to the battery and plug into the shore AC power every now and then to charge. Can I leave that in place as is or is there a better way to wire it up with the motor connection?

One last thing, the battery lead from the motor is not long enough to reach the switch. Was thinking about connecting to a terminal block or possibly use a trolling motor connector (saw this in another recent post but didn't want to hijack that thread).

Thanks
Robert

Voyager
Master Marine Consultant

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USA
5231 Posts

Response Posted - 06/27/2017 : 21:47:13

Robert
Welcome to the forum. I'll give you my personal opinion - you can take it for what it's worth. Others will differ on this.
First, does the Tohatsu also have a built-in 6 or 12 Amp alternator for charging the battery when the motor is running?
If there's no alternator, then a battery selector switch will allow you to disable the starter to prevent inexperienced people (like curious kids) from accidentally starting the engine at an inappropriate time. This is a benefit.
If there is an alternator, however, you run the risk of switching off the alternator battery charging circuit while the engine is running. This will lead to burning out the alternator charging circuit and regulator which would lead to an expensive repair.
Instead, in my case, I have hard wired the engine to the battery with only a 50 Amp fuse inline in case of a catastrophic failure.
I remove the dead man switch lanyard if inexperienced guests are around.
If you plan to get a second battery, then a three position switch is fine: 1-2-both. This will allow you to charge each battery individually or together.
You might wonder why I put a 50 Amp fuse in line. The starter takes more current than the alternator puts out, so you need it for the starting load.
On this point, I ran #6 AWG stranded two-wire cable from the battery compartment to a pair of terminal blocks inside the quarterberth just forward of the transom. The length is 15 feet but the total length of the wire is 30 ft.
I fished the engine cables inside the boat through a hole drilled through the transom. The hole has a rubber cap over it to prevent seawater getting inside the quarterberth.
As always, check with your local electrical codes and have an electrician check your wiring to prevent accidents.
Another essential is to always install a fuse on any circuit from your battery to any DC distribution point, for example, to the engine, to the power distribution panel, the VHF radio, music systems, lighting, fans, pumps, etc.
Lastly always use tinned marine stranded wire for any circuit onboard (never solid wire) and always use wire of the correct amperage capacity needed. Several rules of thumb are included in DIY repair books. Good wire and fuses are not cheap, but they are cheap insurance.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

hsvbama
Deckhand

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Response Posted - 06/28/2017 : 07:13:06

Thanks Bruce. Yes the Tohatsu has a 6 amp alternator for charging. The direct connection sounds like a good approach to eliminate the risk of burning out the alternator circuit. I may add the 2nd battery eventually, but dont think that I will need it. We just got the sailboat. It is in a slip at a local marina. We mostly day sail at this point. Planning on some over night outings, but nothing extended or too far off. I may hook it up to the selector switch for now and then explore the other options. Appreciate the insight.

Robert

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 06/28/2017 : 11:49:56

I used a trolling motor socket/plug as a remote terminal for my OB. That was in an '89, the routing of "opportunity" varies with years. I also put speaker terminals in the cockpit ice bin with the "power port" on the outside but using the same routing.

Frank Hopper

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 06/28/2017 : 15:24:17

Fresh water or salt? In salt water, I'd avoid an external connection and do what Bruce did. (Actually, it was at least partly me when I owned Passage.) If you're in fresh water and want to be able to remove the motor frequently and easy, then Frank's plug makes sense.

A simple way to fuse everything off the battery is to get the type of fuse that attaches to a battery terminal and provides another terminal for the wires. In West or Defender, check the Blue Sea 5191 fuse block and the fuses it uses (5177 for 50 amp). They protect the entire run to the battery and to the electrical panel.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Voyager
Master Marine Consultant

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USA
5231 Posts

Response Posted - 06/28/2017 : 21:28:45

Dave "Stinkpotter", that fuse block is a really great and simple idea - just make the fuse part of the terminal! You literally protect the entire cable run against a potential electrical fire.

I did rewire your original internal terminal blocks for the engine, as I upped the fuse rating and cable ampacity by one gauge. But the blocks and the engine cabling and terminal connectors are perfectly good so they're still the same.

Frank, on the trolling motor connector (plug and receptacle), what's the maximum wire gauge, AWG#4, #6 or #8?

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

hsvbama
Deckhand

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4 Posts

Response Posted - 06/29/2017 : 05:34:52

We are in fresh water. The motor is mounted and ready to go. Had to swap out the 2 spring mount to a 3 spring. That went very well. Support brackets and mount lined up perfectly with existing mount. Just need to wire it up. Appreciate the replies. Still trying to decide on which way to go.

Robert

hsvbama
Deckhand

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4 Posts

Response Posted - 06/29/2017 : 14:02:07

I just ordered the Blue Sea Systems 5191 Fuse Block Terminal, 5177 50A Terminal Fuse, and 6 AWG wire. Going to stop by Academy and check out the trolling motor connector as well. That seems like a good way to join for fresh water cruising and easy engine removal. I will use the lanyard kill switch to control inadvertent starting. Thanks again for the help!

BTW, I'm assuming there are no issues with using my battery maintainer to charge the battery while is at the dock. Planning to keep that on for the bilge pump. At least until I have time to find and fix the leaks.

Robert

Dave5041
Former Mainsheet Editor

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USA
3754 Posts

Response Posted - 07/19/2017 : 13:55:59

Bruce, 6, 8, & 10 are readily available. The various sets are available in 35A and 50A ratings. My plug has 2 "o" rings and I have never had a problem with corrosion in saltwater even though mine is mounted on the outside of the transom.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

Edited by - Dave5041 on 07/19/2017 14:08:35

TCurran
Admiral

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USA
588 Posts

Response Posted - 07/20/2017 : 06:19:55

quote:
Originally posted by Dave5041

Bruce, 6, 8, & 10 are readily available. The various sets are available in 35A and 50A ratings. My plug has 2 "o" rings and I have never had a problem with corrosion in saltwater even though mine is mounted on the outside of the transom.

One of the best ideas/upgrades I did (on the Watkins). Mine is also on the outside, in salt water, and have had no trouble with it (of course I just jinxed it

) I only pull the motor a couple times a year, but not have to climb in the "dungeon", contort to reach the connections, cut the zip-ties to take the motor off and the reverse the operation to put it back on, was more than worth price of the plug. Only issue I had is I had to buy the adapter for the 6 gauge wire (link is to show you the part, I bought mine local) - https://www.starmarinedepot.com/minn-kota-mkr-18a-6-gauge-adapter-for-mkr-18/pzz30617.html?gclid=CjwKCAjwqcHLBRAqEiwA-j4AyOZdF1UAtAs1rQPCFM7iDDxnt-1F_pCz8pHK2muF1Q69nLj_LSnOBRoCn34QAvD_BwE

Tom Curran
1981 Capri 25 Hull #101 "Dirty Debbie"
1988 Watkins 30
PAFB, FL

Voyager
Master Marine Consultant

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USA
5231 Posts

Response Posted - 07/22/2017 : 05:36:35

Dave and Tom - that plug arrangement looks like a great option and provided the receptacle and plug have O rings and it can withstand a soaking in salt water it's good. There's something to be said for not having to shimmy down inside the quarterberth each season.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Edited by - Voyager on 07/22/2017 05:37:43

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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.