Solar trickle charger - what to do with this thing

[thenated0g]

My mom was getting rid of some camping supplies and gave me this solar trickle charger. Pics below.
24v
5W
350mAmps

Is this supposed to be connected straight to a 12v car battery?
My thoughts were that while at a flying event i could have this constantly on the battery i use for charging planes. But a lot of my chargers are limited to a max of 18v i think. Im guessing that the total system voltage is going to be lower than 24 when this is connected, but not sure. Would it be pointless to have this on it at all considering its low output?

 

[PsyBorg]

That's what they call a battery maintainer. People use them on boats where they are not in continual use. For tractors in winter storage.... things like that.

It is for 12v batteries and will feed ~ 17 volts if battery is really low but lowers as current draw drops. According to the few I just looked up the have limiter diodes in them.

Some of them say they can be used when there is a draw on the battery like If you connect your field charger to your car battery you could offset the power drain using that. I believe there should be a circuit board on it that regulates for shorts, over voltage and all that. They are not meant to power things just keep a battery topped off or maybe bring a weak battery back up from sitting if it has not got too low.

 

[Tench745]

I have one of these on my boat. I also used to sell them when I worked at West Marine. In my opinion it is mostly useless. That is the middle sized panel of the three affordable solar panels we sold. The smaller was intended to keep up with the little bit of self discharge a battery will experience in a boat. The medium size was intended to keep up with a bilge pump running intermittently. They output 24 volts "open current" which means when there is no battery in line. It will drop down to a reasonable charging voltage when you hook it up to your standard 12v car or boat battery. Charging current on mine when I had it installed on my boat was never more than 1/2 an amp. If you keep the panel pointing at the sun (means moving it constantly to face the sun) and no shadows fall across it you will get that 1/4 to 1/2 amp input for about 4-5 hours a day, depending on your latitude. That's somewhere from 1-2.5 amps of charge per day best case scenario. If the panel is shaded at all output is cut at least in half. Some panels have a diode in them, and if yours does it's a good thing. If there is no charge diode then the battery can actually backfeed the solar panel and emit all those amps you put in as radiation overnight. Net gain: nothing.