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  Battery Cable: Size Needed

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Author Topic:   Battery Cable: Size Needed
villagerecorders posted 11-17-2006 04:29 AM ET (US)   Profile for villagerecorders   Send Email to villagerecorders  
I need some information on moving my battery from the bilge compartment to under the center console on my 19-foot center console. It looks like I need 18-feet of battery cable. Will 2-AWG work? Or do I need 1-AWG? Thanks.
jimh posted 11-17-2006 08:09 AM ET (US)     Profile for jimh  Send Email to jimh     
The owner's manual for your outboard motor will have information on the necessary size of the cable to use between the outboard motor and the battery. If you follow the recommendations for the outboard motor starting current you should be fine with all other loads.

You can calculate the voltage drop using

http://www.powerstream.com/Wire_Size.htm

villagerecorders posted 11-17-2006 10:51 AM ET (US)     Profile for villagerecorders  Send Email to villagerecorders     
its says under specifications in the owners manual (alternator 35 amps), im not sure if that's the draw on a 2000 Johnson 150 HP engine
contender posted 11-19-2006 11:02 PM ET (US)     Profile for contender  Send Email to contender     
If you go with the larger cable the electric current flows easier and is probably better for the starter and battery.
Jerry Townsend posted 11-20-2006 12:07 AM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Villagerecorders - AWG-2 should work fine - as the recommended allowable current is 95 amp - which will certainly cover the current draw of your starter. Consider getting the marine grade cable which is somewhat more expensive, but it eliminates the corrosion problem. --- Jerry/Idaho
Chuck Tribolet posted 11-20-2006 04:34 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
35 amps is what the alternator puts out. The starter will
probably draw more, possibly a LOT more in cold weather.
I've got a service manual for roughly that motor, but I
won't be home to check the spec until Tu. night. If nobody
posts an answer before then, I'll get it for you.

The starter on my truck is speced at 90A with NO load, and
the amps will go up as the load goes up. IIRC, a starter
under load pulls several hundred amps.


Chuck

jimh posted 11-20-2006 08:25 PM ET (US)     Profile for jimh  Send Email to jimh     
You may have to consult the rigging manual for your motor. It will provide information about the size of wire needed versus lenght.
alfa posted 11-21-2006 02:30 AM ET (US)     Profile for alfa  Send Email to alfa     
FYI, I replaced the old battery cables on my 70hp Johnson with AWG#2. Charging battery is one thing, but the starter asks for a big power (lot of amperes).
Chuck Tribolet posted 11-21-2006 05:48 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Service manual says 30 A at no load for the starter.

Cable sizes:

V4:
1-10': 4 ga.
11-15': 3 ga.
16-20': 1 ga.

V6:
1-10': 4 ga.
11-15': 2 ga.
16-20': 1 ga.

Net: 1 ga.


Chuck

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