Battery cable size question.

[jcarufo]

A question of all the experts please if I may. I plan to move my dual batteries and isolator from the stern to midships in our 17ft Whaler for better weight distribution. There will be a run of about 4 feet from each battery to the isolater and 8-10 feet from the isolator to our 90hp Honda. My question is what size cable would be most appropriate to prevent voltage and amperage drop? Any information would be greatly appreciated.
Thanks for your time,
Jean

[Scaup]

Here's a link that will help you out. I would use 2 gauge wire for both although you could use 4. I tend to over engineer everything. There is no performance penalty for oversizing.

http://www.boatus.com/boattech/cable.htm

[jcarufo]

Scaup,
Thank you so much for the reply. The article and tables are exactly what I was looking for. I found lots of automotive stuff, but little marine. Thanks again,
Jean

[Miss B Haven]

Use Tinned Wire, not straight copper. Rogers Marine should have it. You can't go too big on this.

You will also need to use a good crimp/connector. The crimp tools/dies are very expensive. Get your lengths - have Rogers cut the wire and put the terminals on for you.

[whalerpaul]

Any idea how much to allow for Cranking amps on a 150hp 2stroke yamaha?

thanks,
paul

[Pilar]

Typical starter currents are 100 to 150 amps. This is a pretty short term draw but you need to size accordingly to prevent excessive voltage drop. Overheat of the cables is seldom a problem unless the draw is continuous.

So, if the motor does not start and you end up grinding the starter for prolonged periods .. remember to pause about 5 minutes for every minute of continuous cranking. This will allow the starter to cool off and the battery to partially recover.

You might spend the 5 minutes checking the engine, fuel tanks, fuel pumps, filters, water separators and other things.