Two Summers ago, I was faced with the task of powering my 48V motor without the luxury of readily available AC charger outlet. My web searches lead me to many 12V solar charger solutions, and a few 24V solutions, but I was unable to find any solid direction to charge my 48V Briggs and Stratton system.
To help out those who happen upon this posting, first let me give a little background on my application.
I own a 18ft Bennington Pontoon boat. The boat is equipped with a Briggs & Stratton Electric Motor with the AA0202-101 Remote Controls. When docked with an AC outlet, I used (2) Guest Pro Series 10 Amp Chargers. The Chargers could typically charger (4) 12V deep cell batteries overnight when depleting the bank charge after a busy day on the lake. A busy day would be about 45 minutes at cruise speed, operating an Eagle Magna III fish finder and 3-4 hours of CD deck playback.
Well, to make a long story short, I was cut off the grid and did not want to get a boat slip on another lake. After looking at some pricey marine solutions, I was able to cobble up a residential style system that works great. In fact, it works so efficiently, my system remains at full charge all of the time. My battery bank does not seem to lose any charge when operating the CD deck, fish finder and an AC inverter. When operating the motor at cruise I never see a drop in charge on the gage.
Geographically, the boat is operated in Michigan, and I keep my panel strapped to my Canopy or tilted at a 45 degree angle leaned on the side gate, the panel is never really in the way . In other words, the daylight provides the majority of my power directly.
The system has been fully operational for 2 years. During the winter, I pull the Motor and store it in my garage. I keep the controller indoors. The batteries and the boat stay outside. In fact, I kept the boat in the water last winter, and it proved more convenient than towing it to land storage .
The system is simply (4) deep cell batteries connected in series, a Solar Cynergy PV-SC110J66 66V solar panel, and a Xantrex C40 40 Amp controller to keep a 48V system.
Here is a link to a diagram I cobbled up (Follow the links to manufacturer's specs):
Solar Powered Pontoon Boat Specifications page
I hope this saves you some time and money. I got the panel for $400 used, batteries will run around $65 each, and the controller was $120.
Added by request a walk through video
