Solar Trickle Charger

[b.nelson]

Our 310 is on a mooring in the summer and outside both without power. I am considering adding a solar panel to provide a trickle charge to keep the batteries charged. We have two 4D batteries.

Any suggestions on sizing and if a controller is needed would be appriciated.

 

[Witzend]

I use (4) Coleman 18w panels mounted on top of the bimini. Works great!

 

[BLUTE]

I use (4) Coleman 18w panels mounted on top of the bimini. Works great!

In series or paralell ?

 

[Witzend]

Each panel will put out up to 21v in full sunlight, but are rated at 18W @12v. My (4) panels are wired in parallel and connected to a NC 25A-12 controller which has an adjustable output range of 13.8-16v.
http://www.solarseller.com/flexcharge_wind_hydro_solar_charge_controllers.htm#flexcharge_nc25a___12_volt_controller
The installation worked out well for my boat because the shore charger was already located in the port aft locker. This previous installation had 4 gauge wire running back to the (3) 8D Bats. So I piggy backed on that wire which reduced my voltage drop.
I have some pics I will try to dig out.
http://www.flexcharge.com/flexcharge_usa/products/nc25a/nc25a.htm

 

[rpwillia]

A more modest setup than Witzend's

I have a 15watt solar panel installed as I almost never use the shore power at the dock. The solar panel is wired into my shore power charger as the wires were already run so it was much easier. I mounted the panel on my stern rail. Been using it for 3 years now and it works great. My controller also had a desulphinator circuit which I credit for giving my last set of 4D batteries 3 extra years of life.