Join Date: Dec 2008
Thanked 18 Times in 17 Posts
Rep Power: 9
2 stroke and 4 stroke outboards can work at idle without any problem. The alternator will not produce its rated output (18 A in your case) at idle. If the boat is in a barn now why not charge your batteries with 110V source?
If the boat is in water you can run the engine at idle. If you need higher revolutions you can do so with the gear in forward or reverse.