The lake I live on has a long stretch of no wake zone. That's where I spend 80% of my time when I take my boat out on it. After installing  my system I've noticed that being at idle doesn't help charge much. I'm pretty sure it is a low amp alternator. i am going to order a 105amp. Which one is better for charging at idle?

How many batts do you have? If you have room, 3 is a good idea for a big system. 2 ran together for stereo and 1 for boat. I have 2 29 marine from walmart with a nice system and can go all weekend. I even considered a solar charger while out...but haven't needed that yet.

I have 2. I have a 29 and a 31 with a switch. It'll go all day no problem but, I've noticed that it doesn't charge much if at all at idle and It's my understanding that a 3 wire will charge at idle (that's what I have now just low amp) and a 1 wire will not. I have just a 2 channel amp and 2 6x9's. nothing special.

Thanks for the info. I have a 3 wire now so the wiring should be straight across. Just going to a higher output alternator.

I have a 3-wire and it's wired as a 1-wire, super easy to do and it will charge at idle.  That's the way to go if you have a constant drain on your battery like a large stereo.

I'll Google up a diagram to do that. Is their a benefit to doing that as opposed to keeping it a 3 wire?