5 Watt Solar Trickle Charger - effective?

[Quint]

Well, I got the 12v fridge wired to my house battery directly with an inline fuse. Thanks for the advice.
My next question is this. I live in a condo where I keep my camper on the truck full time. Unfortunately, I cannot hook up a smart charger to keep the battery topped off. Also, I can't install large solar on the top of the of the truck as I think someone might think it an RV. Right now I back it in the parking space and it looks very un-obtrusive. I try to drive the truck and camper every couple of days for 30 minutes to keep the battery topped off in between trips. I might buy one of the small 5 watt solar panels and put it in the dashboard and run the wire back through the sliding windows to the house battery if it will help to charge the house battery at all. The solar panel has a diode to prevent draw during non-charging periods. Any thoughts on the effectiveness or not of this? Also, I found a pretty good website that deals with deep cycle battery draw and traveling considerations:

http://home.mweb.co.za/zs/zs6phd/Deep_cycle_1.htm

 

[jimmythec]

This is from windsun.com,
When using a small solar panel to keep a float (maintenance) charge on a battery (without using a charge controller), choose a panel that will give a maximum output of about 1/300th to 1/1000th of the amp-hour capacity. For a pair of golf cart batteries, that would be about a 1 to 5 watt panel - the smaller panel if you get 5 or more hours of sun per day, the larger one for those long cloudy winter days in the Northeast.
I think the important thing is to not use too large of a solor panel without a " good " 3 stage charge controller.

 

[HERR42]

it ought to work...that is, to keep your battery topped off.

do you have any electronics that are "always on" ? i.e. CO or propane detectors? remote control fan?

these items consume a small bit of power. if you do have them the solar cell must be able to exceed their consumption.

 

[davidshourd]

I have a pair of cheap 5 watt panels on the roof of my camper, though I do have a controler between them and the battery, they keep the batteries topped off perfectly. it is theonly source my batteries have to keep a charge and it has worked great for nearly a year now. If they are getting direct sun the will keep up with a radio plugged into an ac/dc converter on the 12V outlet, keeping the battery 100% while using excess power to feed the radio. As they said above, you want to keep the charge very small unless you get a controller between the panel and the battery.