In a message dated 8/3/07 12:01:25 AM, Joe writes: > I need to size the correct solar charger for my boat this winter. > I have the following batteries -- 4 6 volt golf carts ( 400 ah ) > 1 - group 31 starting batter > 1- group 27 starting battery. > Was planning to last all together and then run charger into all of them > unless > a reason no to do that -- how may watts or millaamps do I need? > If it is just a question of maintaining the batteries during winter storage, all you need to do is compensate for self discharge. This is about 2% a month, assuming that there are no leakage paths. I estimate that you have about 600 amp/hrs of capacity so you need to supply about 12 amp/hrs per month. A 10 watt solar cell should do the job nicely. With that much ampere hour capacity, you do not need a controller. Connect the cell directly to the batteries through a simple diode. Now a real electrician can tell me I'm all wrong. Larry Z ************************************** Get a sneak peek of the all-new AOL at http://discover.aol.com/memed/aolcom30tour