Cheap solar panel charging batteries

[The Danes Are Coming]

We have over the past couple of years been leaving our RV for extended period of time without the possibility of charging the batteries. By "extended periods" I am talking about 4 to 5 month.

We have factory installed solar panels on the roof and for the first couple of times we completely disconnected the starting batteies and left the house batteries to be charged by the solar panels. This worked fine until last time we came back. That time the house batteries was completely discharged whereas the starting batteries could be reconnected and would start up the RV without further charging.

We are unfortunately not very good at solving electrical challanges. We would like to - but we are no experts at all. We think that our problem with our house batteries may have been down to the solar panels not charging correctly or maybe we have had " an electrical leak" that drained the house batteries completely. We are not in a position to dianosticate this issue I am sorry to say.

Now - how to solve this problem?

A good friend of mine is sailing in the Meditaranian Ocean for 6 month of the year. This means that for 6 month ( during the winter) he leaves his boat unattended. He have bought cheap solar panel battery trickle chargers like this and he tells me that every time he return to the boat his batteries are "ship shape and Bristol fashion". These are very simple solar panels that comes pre-installed with "alligator clips" ready to connect directly to the batteries. The small solar panel have even small suction cups on the back enabling you to stick the solar panel inside your windscreen.

We like the simplicity of this setup and we think that a 1.5W trickle charge should be safe enough to connect without risking "cooking" your batteries. All these solar panels will have to do is keeping up with the batteries normal discharge while stored.

Here is my question: Have anyone tried this? Does anyone know a good place to get such solar panels?

We are looking forward to hear what you think.

[TechWriter]

I have 4, 6V coach batteries and the minimum solar I'd use is 2, 135W Kyocera PVs + a decent charge controller.

[Norm4015]

The 1.5W trickle charge will give you about 7.5 watts on a sunny day and much less on a cloudy day. Your static battery drain is much more than that so the batteries will completely discharge after a few months. The heart of a good solar system is the charge controller. An 80-120 watt solar panel with a good charge controller should keep the batteries charged if they are fully charged to begin with.

Before investing in a new solar charging system I would determine what is wrong with the factory installed system and fix it. It should keep the batteries charged.

[ralper]

See my post under Boondocking. "Solar That Really Works". Small or large system the principals are the same.

My battery moniter tells me that I have a constant usage of 0.5 amp hrs. My solar system does not even know it is there. I am a full timer.