Making a solar powered smart charger

Thread Starter


Joined Nov 30, 2018
Although I've done some basic electronics, I'm extremely new to designing and planning out circuits and was hoping to get some help. My goal is to power a single LED chip (~100W) with a battery that constantly charges off of a mini solar panel. The light would be controlled with a dimmer dial, and charging speed isn't a huge concern because the light would only be used once in a blue moon for an hour or so at most. I need help figuring out a couple of things:
1. The "smart charger" system to make sure the battery doesn't get overloaded. If possible it would be great to just completely cut off the charger as opposed to a trickle charge method.
2. I don't know the technical term, but I believe solar charging requires normalizing the voltage to make everything run well.
3. I know my load is predetermined to be a 100 Watt LED chip listed to run on 30 Volts, so would this mean I need a 3.5ah battery? 100W/30V=~3.3A. Additionally, how would I figure out how many volts the solar panel has to draw.
For reference, imagine one of those solar powered lawn lights, but with a dimmer switch on it. I'm looking to make a small, self contained flood light to mount somewhere where it would be inconvenient to replace batteries or run power to. Any help is greatly appreciated, as I'm pretty new to this approach. I've done my fair share of high school breadboard and circuit board building and soldering, but this time around there's no set of directions. Thanks in advance


Joined Jan 29, 2010
hi 117,
Welcome to AAC.
When you say mini solar panel, what voltage and current rating do you have in mind.?
For a 12V or 24V panel and battery set, you will also require Boost converter to get 30Vdc for the LED's.
What ON time and frequency do you expect the LED's to be powered.?


Joined Sep 7, 2010
A great many variables ... (those 100W leds need around 35V) To minimize circuitry (best since it's outdoors and rain is around) , it would be better to have a lower voltage led ....

It's not a good idea to have a 30v or 35V battery .... 24V is better either lead acid or 7s lithium ... this voltage is what most people use for solar , and so there are many cheap power regulators available ...

The solar panel feeds into the regulator , and the regulator charges the battery to the correct level , stops charging when full.

Here's one , 9 Euoes inc postage from eBay ...

Next you need to size the battery and panel .... you say 1hr "once in a blue moon" ... Is this a security light , if so you won't need 1hr ...if for a shed 100W is a lot .... this is crucial.


Joined Oct 29, 2009
Not worth building when you can find them so cheap on line now. You can get the cheap eBay controllers but if you want something a bit better look at the Sunguard products.