adding battery wiring for outboard motor

[guntersville]

Got a catinla capri 22, using 9.9 hp outboard w/alt. battery is below deck at rear of
cabin. thinking of moving battery into starboard aft deck compartment to shorten the length of the battery cable or spend the money for heavy batt. cable back to where the batt. is now. it would be about 25' of wire to run it to the cabin. which way to go? what size wiring is needed?

[smac999]

If the motor starts why bother? The alt is only going to be a few amps. Don’t need big wire.

[Lake-Effect]

yeah, those small outboard magnetos don't output much charging current. If the battery is used for electric start, then that's the biggest current you have to consider. In that case, the battery should be in the back somewhere, and then you only need thinner cable going forward to your panel, sized for the smaller demands of those loads.

You will need a fuse or breaker, close to the battery, for the line to the panel, and you should have one in the run to the motor as well, just to protect that wire. (ABYC)

[tenchiki]

I have a Yamaha 8HT with electric start and alternator. It has an internal 10amp fuse for the starter, and a spec'd maximum 7amp alternator output. You don't need very big wire for those. Note that the permanently attached starter/alternator cable is either #10 or #8 gauge

[Cadence]

Make and model would probably help. Electric start or only magneto charging?

[Bawlmer]

I had a 8 HP Merc with an alternator. The output is very small. #12 will be more than enough for up to at least 15 feet.

[Scrimshaw4]

I have an Tohatsu electric start 9'9 for my dinghy. All it needs is a small 12v lawn mower battery. I'd recommend putting one of those in an after locker since the weight is nominal and then use the same size cable that the motor came with. I use a weather proof plug to connect the cable so I can remove the motor and battery separately. JMHO

[Gary Matthesen]

OK, I was younger and stronger then, but I never used the electric start, preferring to use the limited amount of output from an outboard, to recharge for lights etc. I did not like having to remove the battery for home charging.