Minnkota DC Alternator

We camp a lot on non-electric sites and I think this alternator would be a great insurance policy on keep the batteries charged over long weekends...I have 4...one for the Helix 9, 2 for the trolling motor and 1 for starting, for the record the main engine in a 90 Merc 4 stroke.  Any feedback on this product?  I don't quite understand why this product isn't more popular as it's not terribly pricey and extends battery life on the water.  

Ulbian,

That is just the kind of comment I was hoping I'd get.  Seems like a no brainer to me.

Your starting battery will be charged by the outboard. What this thing does is redirects any excess amps to the destination...whether that is a battery devoted to your electronics or your trolling motor batteries. If the starting battery is at full charge the DC alternator acts as a gateway to the others. So once your starting battery is topped off the others get juice. Since you don’t draw a ton off of your starting battery when you start it up the gateway to the others opens and charges them very soon after having the outboard running. 

I’ve had one on my boat for a few years now and am glad I have it. It’s not a replacement for an onboard charger but it definitely has extended some long days. The past three years I’ve had my onboard charger plugged in twice each year. Once when I pull it out of storage and another time mid winter to keep the batteries topped off. Even with hard use this thing has kept those trolling motor batteries up at or very near a full charge. When I’ve plugged the onboard in after use the trolling motor batteries reaches full charge within minutes. Prior to having it installed it would take quite a bit longer. 

I am wanting this alternator to top off the trolling motor batteries and possibly the Helix battery.  

Which of the 4 batteries are you trying to keep charged up? The alternator won't supply enough power to recharge the trolling motor batteries, but may keep the starter and accessory battery charged. A battery at 50% would take 5 hours to recharge with a 10 amp charger. You'd have to spend a lot of time and gas to get your trolling motor batteries fully charged.