what size battery cables

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floatmiboat

Petty Officer 3rd Class
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Sep 4, 2010
Messages
90
I was recently told my battery cables are way undersized for my outboard which is a 1997 25 hp merc with remote controls. What is the correct gauge to run? The cable I'm currently running is about 12 gauge. Thanks
 
MH Hawker

MH Hawker

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Jul 13, 2011
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5,516
Re: what size battery cables

I dont know what the exact amp draw is for that motor but I would think at least a 6 or 8 gage wire.
 
JB

JB

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45,907
Re: what size battery cables

They don't make wire big enough to be too big.

Say 4ga.
 
Faztbullet

Faztbullet

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Mar 2, 2008
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Re: what size battery cables

If I remember correctly it a stranded #2.........
 
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floatmiboat

Petty Officer 3rd Class
Joined
Sep 4, 2010
Messages
90
Re: what size battery cables

OK, thanks. I wonder if the cables I have now could have caused me to go through two starters and a solenoid in the past two years?
 
Faztbullet

Faztbullet

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Re: what size battery cables

I wonder if the cables I have now could have caused me to go through two starters and a solenoid in the past two years?
Click to expand...
If to small and amp draw excessive..yes
 
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oldman570

Lieutenant Commander
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Mar 25, 2011
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1,615
Re: what size battery cables

As Fastbullet stated the factory cables on my 25 are of #4 gauge stranded copper and larger #2 would be better. Smaller wire will cause the brushes in the starter to arch more and cause them to ware more than they would if higher amperage were present. This will have the same effect on the contacts in the solenoid also. JMO
Oldman570
 
Texasmark

Texasmark

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Dec 20, 2005
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14,557
Re: what size battery cables

Starting current for my 3 cylinder 90 is spec'd at a max of 120 amps and for the 4 cylinder engines of 100 to 125 hp is 150.

Just taking a hp ratio, for say the 100 hp at 150/4 for 25 hp = 38 amps. #4 will carry twice that especially in intermittent service with short runs like you have in your boat. Looks like you are good to go with room to spare. I realize that we only have 1 volt to loose in the wiring from the battery to the starter but still........

Mark
 
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