battery placement and cable guage questions...

[Mickyfinn]

Hi there,<br />As part of a bigger project on my '75 Wellcraft 20 CC, I'm considering moving my batteries from the stern to under the center console (long story, but it would make some issues much easier). The fuel tank is also under the console, so there's that to consider but the question is what size wire to use to make the longer battery cable run. I looked on the starter (1990 Johnson V4 120ph) and couldn't find the amp draw to plug into the chart. The cable run would be no longer than 15' from the selector switch to the motor. Any idea what that motor draws or ideally what size wire would be recommended? I'm also interested on thoughts on the batteries and fuel tank sharing the console. I'm planning on battery boxes and placing louvered vents (clamshells?) on the sides of the console and also venting the tank outside the console as well.<br /><br />Thanks for the input!<br />Evan

 

[Paul Moir]

Re: battery placement and cable guage questions...

I belive for that engine it's #3 to 15' and #1 if over. I would probably run #2. The specs may be in your outboard owner's manual, so if you have one look it up in there. If you don't, I'm sure someone will post if I'm wrong.<br />Sounds like you've got a good plan with your battery boxes.

 

[DJ]

Re: battery placement and cable guage questions...

Batteries/Fuel in the same area----BAD decision.<br /><br />A typical center console has the batteries in the console and the fuel under the seat, or vice versa.<br /><br />DO NOT combine the two.<br /><br />Wire guage recommendations have been made. I agree with those.

 

[Mickyfinn]

Re: battery placement and cable guage questions...

Thanks guys,<br /><br />I was thinking #2 wire would do it but I'm glad I asked. As for the battery/fuel, it wouldn't be my first choice but my options are limited in placement. The biggest issue is getting all the cabling where it needs to be. The simplest way out by far would be to combine the two under the console. The console is also the best ventilated hold on the boat. I think it can be done safely, I'll just make that extra effort to make it so. I will take a look at the option of installing a new chase to put one of the components under the seat. I'm not sure how feasible that is, and losing that valuable storage space will be tough. <br /><br />Thanks for the suggestions and info though!<br />Evan

 

[Texasmark]

Re: battery placement and cable guage questions...

Engine shouldn't draw more than 100 amperes to start. A 150 cu in gas farm tractor runs 100.<br /><br />15' on a very intermittent 100 amp load can be carried on a #6 easily. Remember, size is related to heat rise/hence voltage drop along the wire. #6 for 25' (not 15) is only a 3% drop in voltage, but that's for a service entrance "Mechanics in Agriculture" Phillips, 1967, where amps are understood to be continuous. <br /><br />When you are starting your engine, you have a very, very, intermittent 100 amp load; not like wiring your building or your air conditioner.<br /><br />You aren't on it long enough for it to get hot and if you were, before you used it again it would have normally had time to cool down.<br /><br />On battery and fuel, I'd say just know what your risks are and be careful. No fumes, no sparks, no hazard. Your tank's fuel vent is outboard (on the side or stern). Your fill spiggot is in the same place.<br />How many outboards have I seen with 6 gallon tanks (removable connectors) mind you, under the splash well where the starting battery happens to also be located. Some have sliding doors for astetic reasons which also happens to seal it up. Don't remember the last time I saw a boat fire.<br /><br />If you are concerned, Put a blower and vents on your console, like regular inboard boats have.<br /><br />Besides, it takes a pretty heavy concentration of fuel air to explode and you have to get the right mix and the right spark. Lotta variables. Not going to just start a fire with fumes. Gotta get the surfact temp (right at the surface) of the fuel up to the ignition temp of the gasoline to start it to burning.<br /><br /><br />My 2c.<br /><br />Mark