A Small Garden Railroad: Solar powered railcar Part I

Sunday 7 April 2019

Solar powered railcar Part I

The original plan

Due to a few Youtube videos of solar powered garden trains I became fascinated by this idea and started an experimental solar powered model rail vehicle. After some (not to successful) searching on the internet for information on similar projects I realize I had to figure it out myself as much as I could. Because I am not very skilled in electronics I decided to buy on Conrad a “Solarhouse” and a motor with gearbox. Both kits are from Sol Expert (#40212 “Solarhaus” kit and #90015 “Universal getriebe”). See pictures below.

The house kit was bought because it has some electronic unit in it that charges the battery (or at least, that was what I thought it was, just keep reading...).
This kind of electronic unit is certainly also present in most cheap LED garden lights of course, but mostly the electronic components in these have no visible codes or markings on it. As I want to examine what components can be used for making a similar unit myself, I wanted something with these codes still visible. I noticed this was the case on the Sol Expert kit.
The kit itself is very straightforward (luckily); with a switch you can turn the LED on and off. I figured that I could replace the LED for the motor which will make the wheels spin and that would be it for me (I like things simple). No RC control desired at this moment, just want to let it work for now. The Sol Expert 0,6 – 6 volts motor is designed to run on the solar charged 1,2 volts battery. If I keep the model as light as possible, it will work (I hoped).

The second plan (after some wise advise)

Fortunately I received some very helpful advise on the Garden Railway Forum that made me understood the electronics a bit more. There is NO special charger unit in it as I had guessed. The solar panel just charges the NiMH battery. The two components are a LED driver that shuts off the LED when the voltage drops below a certain point, and an inductor.
The advise was to run the motor straight off the battery and not to replace the LED with the motor hence the chip has some current limiting function.
So, the plan is now to keep the electronic unit as it is (it will be a headlight for the railcar) and connect the motor directly to the battery together with an on/off switch. See the drawing schedule below.

Next, figuring out how I build it on some sort of base or chassis and what it would look like...
To be continued!