http://www.stayncharge.com/

"The All Charge and Stay'N'Charge

Never worry about charging your trolling motor batteries again!

Our small lightweight “smartbox” will actually charge your batteries using your boat or tow vehicles charging system while you are towing your boat down the road or while you are on the lake racing to your next fishing hole.

Our products are unlike anything else on the market. Not only will they allow you keep your batteries topped off all day and night while you are fishing but they will prolong the life of your battery by maintaining and conditioning them. Many anglers have even found that, with our units installed, they can downsize their batteries, reducing weight in their boat thereby increasing their top speed and reducing their fuel consumption."

Found this a few weeks ago and about to order. it seems great for guys running LEDs, HIDs, or other 12v lights/acc off trolling motor batteries that are worried about runtime. Per the FAQ a 150+hp outboard takes approx 10 min running for every hour of trolling (24v)on high to recharge to full, so a CDI motor should charge them up quick, fast, and in a hurry! Another thing i like about it instead of foolin with an on board charger you hook a regular 12v charger you probaly already have to the crank batt and it keeps em all juiced up.

Sounds pretty innovative thought maybe one of you guys may be interested.