2 Big Twins and one battery

[tmcalavy]

Got an electrical question, so need help from the pros. Mods, move this post if it isn't in the right place. It's about two old E-rude Big Twins so I posted it here.
I've got an early 60's 15 foot aluminum runabout (Texas Maid) that is powered by two late 50's Evinrude Big Twins...56 Lark and 57 Big Twin. Both outboards are equipped with solenoids and push button starters. I want to install a simple battery switch so I can start both off of one battery. That's all the battery is used for...providing power to the starters/switches. Looked in the Iboats mall and found battery switches like the photo I have attached. Is this what I need? No experience with this, so I'm in the dark when it comes to doing this. Whatever I buy has to have simple hookups and solid directions/diagrams. Any suggestions? Also attached a pix of the stern of the Texas Maid showing what the splashwell looks like, with the Big Twin and a Johnson 18 hp in tandem on the transom. Same concept as the dual Big Twins...only the Lark will be where the smaller 18 hp outboard was mounted.

 

[Mas]

Re: 2 Big Twins and one battery

I don't know, but your boat & engines look straight off the showroom floor! Nice!

MAS

 

[tx1961whaler]

Re: 2 Big Twins and one battery

A tiny bit of more information needed:
Do either have generators?
Are they both manual shift models?

 

[jay_merrill]

Re: 2 Big Twins and one battery

Since you have no charging capability in these engines, you don't need a switch. Just split the positive and negative leads and run them to the respective motors.

If for some reason you decide to install a "Rule type" switch, just wire it as if the engines were batteries and the single battery were an engine. You can leave the switch in "Both" most of the time, and isolate the individual engines when you want to.

 

[tashasdaddy]

Re: 2 Big Twins and one battery

i agree with Jay, you could actually connect both sets for battery cables to the battery terminals themselves, with out any fancy wiring. just keep the battery charged when stored.

 

[F_R]

Re: 2 Big Twins and one battery

You do know that the '56 is a 6 volt system, don't you? OK, so people do run them on 12 without apparent harm, as long as you don't crank it for more than a few seconds at a time.

Another agreemant, you don't need the switch. No need to complicate things or spend money on something you don't need. The switch is for dual batteries, not necessarily dual engines. Just run the cables from both engines directly to the battery.

If you were to have generator kits on twin 35's, you would need a "Current Coupling Kit". Just diodes and a heat sink. This is just a tidbit for information purposes, the 30hp did not have a generator option.

 

[tashasdaddy]

Re: 2 Big Twins and one battery

F_R is it possible to put a 12 volt starter on the 56? just a thought.

 

[tmcalavy]

Re: 2 Big Twins and one battery

Great info...thanks. I wondered about needing a switch since neither motor has a generator/alternator. Think I'll install a router panel on the inside of the transom, so I can have cables in place to route to the battery and use shorter cables on the outboards to go to the router/connector. Both outboards are rigged for 12V battery...both starters were fried/dead when I got the motors. Had a couple of 59 Johnson 35hp Sea Horses laying around the shop at the time (they were a bonus with the boat when I rescued it) and the starters tested good and bolted up, so each of the Twins has a larger, stouter 59 starter on it. I believe those are 12V starters. I never have to lay on the starter with either motor, they fire right up as long as the carbs are clean and they're getting gas. Any ideas on a simple router/connector/splitter that I can mount on the inside of the transom...are these common enough to be a stock item? Who carries them? A bigger, single tank (12-15 gals.) and split fuel lines is the next project for the Maid.

 

[F_R]

Re: 2 Big Twins and one battery

F_R is it possible to put a 12 volt starter on the 56? just a thought.

Yes, if you replace the bracket too. Keeping in mind that a Johnson uses a different bracket than an Evinrude or Gale. You can use a Johnson bracket on an Evinrude, but not an Evinrude bracket on a Johnson. Reason? Different hood mounting.

 

[jay_merrill]

Re: 2 Big Twins and one battery

To split your battery connections, just fasten the battery lead to the two engine leads with a stainless bolt, washer and nut. Once this is done, wrap the connections well with electrical tape. This is definately a low tech solution, but it works just fine.