Let's Make Robots!

solar trickle charger-solar engine

Hi, can anyone help?

I am trying to make my robot battery powered with trickle charge with two solar panels.

So far I have just tried 6v solar connected to battery and circuit with diode protection but this doesn’t work.

My next thought is to have two battery supplies, switched by relay when one is running low and the one not being used is trickle charged with the solar.

Trouble is I have been reading that the batteries wont charge until the solar voltage is above the total battery supply (5v). I live in the UK and on a gray day (which is most of the time) my solar panel only produces 3-4v.

So now I think I have to add a solar engine which apparently the solar panel charges a capacitor to the desired voltage (in this example 6.8v) and then releases it to a load (motor or light), but in my case, battery pack and then stops for the cap to charge again..
I and looking at the
"Chloroplast" solar engine. Circuit attached.

my previous thinking was that capacitors only charged up to a maximum of the same voltage that it was receiving i.e. 3-4v

My questions.
Is a solar engine the right way to go? Or does anyone have a better ideas.
is there a better or more suitable circuit as some of the components in the
"Chloroplast" solar engine
are US parts? Or does anyone know the European equivalent.
I thought Caps only charged up to a maximum of the voltage that it was receiving i.e. 3-4v. is this true or will it charge up to the 6.8v?

Thanks to anyone who can help.

solar_engine.gif10.9 KB

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I would say forget about the voltage boosting.   I dont think it will do what your thinking.  if anything, it might be a burst of 6v for a small period of time.   or at an even more reduced amp.

you have 2 panels?   what does your 5v battery consist of?  a single 5v cell, or some combination (4 x 1.2v)?  NiMH?   you could use each panel to charge half the battery.

6v to the battery would be an OK charge for 5v battery.

keep in mind, the diode will reduce your voltage (0.6v) as a cost of doing business.

can you double your panels?   or use smaller battery?