cable lengths

[bob johnson]

I am wiring up my boat and I have the two batteries under the seat I am making for the drivers helm. I don't know the exact length, but my steering cable from Teleflex was a 20 ft version....the battery cable starts a little closer to the stern but it has to snake its way up and into the motor...so I am guessing the cable will need to be about 20 ft. the manual says that cables should not be more than 20 ft!! and they recommend 1 gauge for 20 ft....

can I install a battery switch at the stern and run big cable to that... then run the slightly smaller wire from the switch up through the motor harness passages ( small)
to the starter?? Its not a cost issue...its an issue of getting that BIG cable through the passages and opening into the motor and along the side of the motor to the starter...

I REALLY want to keep the batteries up front!!!!!!!!!!!

thanks


bob

 

[Grandad]

Hi Bob. The reason for minimum cable size recommendations is to limit the amount of voltage that is "dropped" throughout the length of the cable. Using the correct size of cable for only part of the circuit will only partly protect it from voltage drop. How much the voltage will drop in a circuit will be proportional to how much length of the circuit was undersized. There's no free lunch. - Grandad

 

[Fed]

Only the extensions have to be 1 gauge then original motor cables stay the same so fitting an isolation switch to join them is fine.

It's in your book Bob if you have the real book.

 

[bob johnson]

Only the extensions have to be 1 gauge then original motor cables stay the same so fitting an isolation switch to join them is fine.

It's in your book Bob if you have the real book.

what chapter?? I looked pretty good through electrical and didn't see it...

but I just bought 25 ft of black and 25 ft of red 1 awg cable!!!

grrr I could still do it if I have too tight a fit going through the entry part of the motor

bob

 

[gm280]

what chapter?? I looked pretty good through electrical and didn't see it...

but I just bought 25 ft of black and 25 ft of red 1 awg cable!!!

grrr I could still do it if I have too tight a fit going through the entry part of the motor

bob

That's what rotary files are made for, unless there is no real-estate available to open up the hole, then you are stuck. JMHO!

 

[Fed]

Here you go Bob.

 

[bob johnson]

Here you go Bob.

what book is that? that's not the manual for my model outboard! Mine covers ONLY 90, 105, 115 150 and 175 HP 60 degree loopers made in 1997

but it basically says the same thing my manual says... I wonder what they are calling "extensions" what on the battery cable is NOT an extension???

bob

 

[lmuss53]

Youi have stock, factory cables coming out of the cowling now don't you?

You can run the 1 gauge to where it meets the stock wires from the motor and use the factory cables from there, can't you?

I'm asking because I am not certain, I would think if you bring adequate power to a point where the stock wires can pick it up, the stock wires would be good from that point on.

I would find a spot in the stern and put a big motor dedicated battery there. JMO

 

[bob johnson]

Youi have stock, factory cables coming out of the cowling now don't you?

You can run the 1 gauge to where it meets the stock wires from the motor and use the factory cables from there, can't you?

I'm asking because I am not certain, I would think if you bring adequate power to a point where the stock wires can pick it up, the stock wires would be good from that point on.

I would find a spot in the stern and put a big motor dedicated battery there. JMO

all the motors I have rigged had the battery cables seperate from any type of harness, and they ran all the way to the battery!!!!!!!!!

 

[Fed]

It's from a 1988 OMC manual Bob, covers 90HP up to 175HP crossflows but as you say they use the same chart for others.

Battery Cable Extensions
Extensions are the part that's been added on to the original part.

Total Extended Length
The total length of the extended part.

Trust me, I once asked my wife about interpreting the meaning of this and she knows everything.

 

[moi]

You don't need 1 gauge wire to run a 12 volt starter motor even if it is 25 feet away. :lol:

 

[bruceb58]

You don't need 1 gauge wire to run a 12 volt starter motor even if it is 25 feet away. :lol:

Depends on the current draw which will depend on the motor. My 7.4L came from the factory with 1 gauge and it's cables are much shorter than 25 feet.

If the OP adds cable to his existing cables, he will increase his voltage drop...that's a given. How much increase is tolerable is the question. Since he has a carb'd engine, probably not a big deal but if an engine has EFI, then it is a big deal.

 

[Fed]

The downside of fitting a switch at the transom to join the cables is you would have to run 4 wires from the batteries to the switch.
If you nut & bolt & insulate the lugs at the transom you will only need 2 wires up to the batteries/switch.

Edit: Make that 4 into 3 wires, I'm not really with it this morning.

 

[bob johnson]

The downside of fitting a switch at the transom to join the cables is you would have to run 4 wires from the batteries to the switch.
If you nut & bolt & insulate the lugs at the transom you will only need 2 wires up to the batteries/switch.

Edit: Make that 4 into 3 wires, I'm not really with it this morning.

I am thinking that might not be true.

if I run all the wires from my batteries to an single battery switch made for 2 battery systems....then there would be JUST a + and a - cable leaving the switch and heading back to the stern...then at the stern I install just an on -off battery switch...I could use that just as a connection point with it also being a hidden anti theft device...with the main battery shut off being up with the batteries which would get normal use... since I always leave the keys with the boat... so from the batteries all the way to the stern I run the expensive large dia cables...and from the rear battery switch I run the smaller dia cables that easily fit through the opening of the motor cover.

but since I wasn't sure a week ago if I could do it...I went ahead and bought 1 awg cable that will fit the whole length from batteries to starter....if I have issues getting all my wiring and gas line through the motor cover opening...ill go to the rear switch idea

bob

 

[Fed]

Correct Bob but you'll need a double pole switch to cater for the negatives. More places for something to fail.
I've extended in the past simply using lug to lug with SS nuts, bolts, washers & heatshrink

 

[lmuss53]

I would not remove the original cables from the motor. I would use the #1 wire to a place where you can tie it to the original motor wires and connect them together there either with a switch as you describe or lug to lug with SS bolts and plenty of shrink wrap as Fed described.

I like the idea of a hidden switch as a safety/security set up for when you are away from the boat. It also makes for a good place to connect the wires and can be mounted to keep them secure.

You can use something like this, big wire runs from batteries to one side, motor hot lead runs to the other side of the switch. The ground I would just do lug to lug.

http://www.iboats.com/Blue-Sea-M-Se...8026505--session_id.210243428--view_id.238083