I've got the engines out of my Formula SR357 and am going to re-rig the engine compartment.

The cables going from batteries to switch and fron switches to starters are size #6. Mechanic says go back in with #1. Is that going to improve/change things enough to warrant spending the money that way?

What is consensus on size battery wire to use? What about attachment of fittings on end of cable?

Thanks

Poorsche

www.boatmat.com

How long are the total runs including the switch? Seems # 2 with good connections would be enough. I like to use a jumper between the negative post on each battery and then run the negative to the block for each battery. This will effectively increase the carrying capacity of the ground as long as you are starting on one battery only.

I used 1-0 when I rerigged my old boat. It made a dramatic difference in the cranking speed. Before the starter always sounded like it had a weak battery.

Mark has the nicest battery wire that I have ever used. This stuff is more flexible than 1/2" rubber fuel line. It's not cheap, but this is the wire that I use. I buy the crimp and shrink tubing from Napa.

http://www.madelectrical.com/index.shtml

The required wire size is relatively simple math. Smaller wire has more resistance to current flow. There are several other things that will affect resistance. Every connection will induce some amount of resistance. The fewer connections, the better.

If you know the current requirements of your particular starter under start load, the length and wire size of the cable used, I can calculate the percentage of voltage drop and the actual voltage drop. The ground wire or connection is also a factor in this calculation. The biggest culprit is the inrush current. This occurs at the moment the connection to start is made and can be several times greater than the actual run current. This is where poor connections and too small wire size really hurt you. This combination causes the starter to work extra hard which causes extra heat which over time can cause distortion in the starter and eventually failure. The formula is something like this. Resistance equals less voltage which causes current to increase. Bad !

In general, the bigger the wire, the better. That is up to a point. 4/0 cable might be better in most technical regards, but may not be practical for every application.
Somewhere in between might be best. #6 seems too small to me. #2 might be adequate for many starters and a little larger might be even better. I'm sure racers don't want 200lbs of cable in their engine compartment. Are you a racer or a pleasure boater who needs battery power other than starting?

Get extreme duty professional crimps done on all your cables and use red or black heavy duty thick wall heatshrink on the ends to identify the polarity.

That's the way I would do every cable.