Wouldn’t it be great if Ryobi 18v power tool batteries could be charged directly from a 100 watt solar panel? A while back I developed a prototype which achieved this aim successfully. Products like this should already be on the shelf.
Fig. 1 Inside OEM charger showing top of circuit board
With solar power, efficiency is a good thing. The normal route involves the solar panel energizing a charge controller, which charges a battery, which powers an inverter, which powers a DC power brick or switching power supply, and steps back down to DC and into the 18V battery. This is hideously inefficient.
To get around the problem, I modified an off the shelf OEM Ryobi 18v battery charger. Inside a CC-CV DC converter circuit was installed. The current limiting feature is like an electronic fuse to help ensure safety.
The result is an OEM-appearance Ryobi charger that can be plugged directly into a 100 watt (or even a 25-50 watt) solar panel and charge power tool batteries all day long directly from the sun. This is a great capability for the field in general, with applications ranging from camping to remote work sites.
Fig. 2 Modification work (see videos below for better detail)
Better versions of this charger are to be developed in the future. If you’re interested please follow the blog or subscribe to my YouTube channel. Thanks for reading! DD
Below are some videos of the Ryobi 18v Solar Battery Charger in action plus hands on DIY workbench demonstration of the modification and engineering process.
Quick Demo video – Ryobi 18v Solar Battery Charger:
Part 1 of modification process:
Part 2 of modification process:
Solar Thoughts blog 
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One response to “Ryobi 18v Solar Battery Charger DIY project”
[…] charge. I tackled this problem by placing a boost circuit inside a Ryobi 18V One+ battery charger. The page about my Ryobi solar charger is here. To this day that charger remains one of my favorite possessions and serves me […]
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