battery cable length, how long?

[makoo19]

I have my battery at the stern of boat and would like to move it under center console which would be about 13 to 14 ft. what gauge cable would you recommend,is this too far of a distance to turn motor? battery has 715 cranking amps.and motor is 140 suzuki 4 stroke ,thanks.

 

[JB]

Re: battery cable length, how long?

Use the largest size MARINE grade cable/wire that you can afford, Makoo.<br /><br />Not smaller than 2-0.<br /><br />You will save yourself a lot of grief.

 

[18rabbit]

Re: battery cable length, how long?

You have not provided enough info to get really specific about an appropriate battery cable size. Here is the general guideline.<br /><br />0 – 3.5ft use size AWG 4 wire.<br />3.5 – 6ft use AWG 2 wire.<br />6 – 7.5ft use AWG 1 wire.<br />7.5 - 9.5ft use AWG 0 cable.<br />9.5 - 12ft use AWG 00 (a.k.a. 2/0)<br />12 - 15ft use AWG 000 (3/0)<br />15 – 19ft use AWG 0000 (4/0)<br /><br />Presuming this cable is for starting your engine, bigger cable is better. You want to minimize the voltage drop through that cable. Typical starting systems have a .2v drop, add to that a 3% drop in the battery cable (.36v for a 12v system) and you are down .56v before you even get started. Bigger is better in this case. You should be ok with 3/0 but 4/0 would be a better choice. Either way, you are going to have some big, expensive cables stretched across your deck.

 

[WSUDERMAN]

Re: battery cable length, how long?

Makoo, I have just done this on my boat, moved both batts forward 14 ft from the engine. I ran 4 gauge cable based on a .5v drop from the cable distance and gauge (Used the calc on this page...<br /> http://www.powerstream.com/Wire_Size.htm ).<br />BUT!!!<br />JB, <br />From watching this board for 3 years , I have come to respect your opinion... <br /> This has been working fine for 2 months now. In your post you suggest nothing less then 2-0. <br />What have i gotten myself into! What kind of problems will i need to watch out for...<br /><br />Thanks

 

[18rabbit]

Re: battery cable length, how long?

Originally posted by 78FOURWINNS:<br /> ... I ran 4 gauge cable based on a .5v drop

Did you run AGW 4 or AGW 4/0?<br /><br />Excellent wire/cable calculator!!! Thanks!

 

[Paul Moir]

Re: battery cable length, how long?

I'm always afraid of this happening to people, so just to make sure: Did you calculate for 14' of wire or 28', ie there and back?<br />What's your starter current draw?

 

[jlinder]

Re: battery cable length, how long?

78FOURWINNS,<br /><br />1. A .5v drop is 4.2%. Specs call for a maximum of 3% voltage drop.<br /><br />2. A .5v drop w/ 4 ga. means you speced if for a 60 amp load during starting, according to the table given above. Is that what your starting current is? Sounds pretty low.<br /><br />3. You say you moved it 14ft. forward. Is that raw distance, or the length of the wire? A lot of people make the mistake of using the straight distance instead of the wire length.

 

[jlinder]

Re: battery cable length, how long?

78FOURWINNS,<br /><br />1. A .5v drop is 4.2%. Specs call for a maximum of 3% voltage drop.<br /><br />2. A .5v drop w/ 4 ga. means you speced if for a 60 amp load during starting, according to the table given above. Is that what your starting current is? Sounds pretty low.<br /><br />3. You say you moved it 14ft. forward. Is that raw distance, or the length of the wire? A lot of people make the mistake of using the straight distance instead of the wire length.

 

[WSUDERMAN]

Re: battery cable length, how long?

i ran a 4 gauge cable 14 ft forward. This was the actual cable run distance.<br /><br />yea, its a bit more than what specs call for...<br />I believe i am slowly loosing my batt because of it. <br />60 amps was just a guess.

 

[jlinder]

Re: battery cable length, how long?

I am sure there are a lot of other people who could estimate the current draw better then me, but I would change the estimate you need more than 60 amps for the starter.<br /><br />The only spec I could find is from the Seloc OMC manual (that is what I have) and they say a Delco starter should draw less than 190 amps (page 7-26).<br /><br />I know you have a much different motor, but I would try doubling the current draw to 120 amps and redo the calculations. In this case the reccomended wire comes to out as 1/0 AWG