Battery cables

[striper56]

I am moving my batteries and need to lengthen the cables from 11 feet to 21 feet. I have a DF250 AP Suzuki. What size cable should I use?

Thanks

[caper]

2/0

[striper56]

Just for my own knowledge why such a big jump in wire size? I currently have what looks like #2 wire. The wire does not have numbers on it just the letters SEIWA and is not tin coated. Will the 2- 2/0 wires fit thru the rubber grommet on the motor?

Thanks

[kmoose]

Originally Posted by striper56

Just for my own knowledge why such a big jump in wire size? I currently have what looks like #2 wire. The wire does not have numbers on it just the letters SEIWA and is not tin coated. Will the 2- 2/0 wires fit thru the rubber grommet on the motor?

Thanks

On a 20' run 2/0 tinned copper is good to 150 amps. Find out what your starter requires and I will bet 150 amps is marginal.

Why are we putting batteries 21 feet away from the motor?

[striper56]

I looked at the starter and didn't see any info on how many amps it draws. I went on line and couldn't find a definite answer. I'll keep looking.

I am moving my batteries forward to the storage area between the seats on my Sceptre because every time I get on the boat a have to put my scupper plugs in. I had the batteries in the stern about 12" forward of the transom when I had my Yamaha with no issues. Now with the extra weight of the Suzuki it's an issue.

I might be able to cut a foot or two off the length of cables if I run them under the deck over the top of the fuel tank.

[erebus]

Blue Sea Systems circuit wizard.
http://circuitwizard.bluesea.com/#

Very helpful.
Need to have amp load of the circuit and the length of the conductor in both runs (out and back).
A 150 amp circuit running 40' (20 feet out and back) would require a 4/0 wire.
That seems excessive to me considering the starter is a very intermittent draw.
Might be better to find the amperage of the alternator and upsize from there.
I think I used 2GA on my Sceptre with a 225 2012 ETEC when I moved the batteries to midships from the stern. Only about a 10' run though (each way) and my alternator is rated for 55 amps.
Circuit wizard says I need a 4GA for a 55 amp alternator. So upping it to 2GA gives me some wiggle room. (wizard recommends 0GA for 150 amps)
Starts fast and has had no issues for many seasons. (I think the ETEC came with 10' of 6GA for the factory battery cables.)
Just my .02 cents USD.

[Old'sCool]

Genuinedealz is great to deal with and has a calculator on their site.

[uncleboo]

The longer you run, the heavier the wire.

[striper56]

I spent more time on the www looking for the amp draw of the starter with no luck. Any suggestions on where I might find this info.

[kmoose]

I searched for you and found a couple of people that checked current draw with an amp meter loop. On a 5.7 Mercruiser it was 180-200. The consensus on outboards seemed mostly in the 150 range or a little less.