Humble Electronics #003 - Solar Garden and Lithium Battery Chargers (Summer 2023)

 Again I have Big Clive on YouTube for this project but it went in a silly direction. He has showcased how rechargeable Lithium batteries are being thrown away in disposable vapes and that you can carefully harvest the batteries for personal fun and 5V power. Here's a link to one of many videos he's done on the subject. You can also harvest old cell phone batteries to run your 5V lights longer.

His suggestion is to use a TP4056 single cell lithium charger that contains an over/under voltage and current protection module to safely use and recharge the lithium cell.

 

This picture comes from an Amazon listing that's not an affiliate link ,but I will consider being one in the future. There is a USB C version also available. I have some unused micro USB cords so this will put them to good use.

Big Clive also explained, in one of his many videos, how you can change the charging current by removing R3 and replacing it with a resistor with a value of 1.2k to 10k ohms. The higher the resistance the lower the current. The current can range from 130mA to 1000mA. This is a screen cap from one of his videos with my reference scribbling:

I purchased some modules and threw this together with an old battery from a battery bank that didn't charge well anymore. The board limits the charging current if the battery is under the lower safe limit. I used solid core wire, a 2.2k resistor and a screw terminal barrel jack. I insulated the ends with automotive electrical tape. Bending the wires on the resistor with flat jewelry pliers to fit was fun and it wasn't too hard to do. I used the existing wires on the battery after I removed the old charge board. They just happened to look like mine.

Pretty humble huh? but it's a usable prototype and I use it to test some LEDs to see if the connections are good and polarity is right. I have a male screw terminal barrel jack that just has wires at the end that can be plugged into a breadboard. It really just needs to be securely mounted in a box.

As suggested by a commenter on a Big Clive video (I love reading video comments), I replaced the R3 resistor with a pair of female header receptacles. This allows me to insert any THD resistor that I would like to use to charge. The lower currents take longer but they won't heat the chip as much as the higher charging current can. Then, I did as Clive suggested and put on some connectors to the battery end. I chose 2 wire female JST connectors that come ready to use. As long as I use the same style of connectors in other projects, it will make for ease of replacing and charging batteries without having to place a charge circuit in each project. And I hot glued the end for some protection and strain relief.

Kind of ugly but it works, maybe. At this point I got gun shy and read too much about lithium batteries catching on fire and haven't soldered the male connectors on the batteries I want to use. Some batteries have wires or tabs already in place and some don't. I honestly didn't know how dangerous these batteries are, they cause extraordinarily hot fires, that they catch fire in the trash potentially harming sanitation workers, and water only makes the fire worse. I can't afford to burn down my house. I know many people are using these and doing it without having any problems. I just have to gather up the bravery one day and do it.

I haven't completely given up on the idea though because then I created the title of this post (please excuse the messy desk):

I had three silly solar garden lights from the Dollar Tree. I disassembled them. (I saved their batteries and charging circuits for other projects.) Checked the voltage each of the cells produced, about 1.5V, and wired the three up in series to the module's input terminals. I glued the whole setup to a piece of scrap 3mm plywood. I wish I painted the wood board green. I did install a female JST wire on the charge terminals only. It puts out 5V on the supply terminals so I think it will charge a battery when I'm ready to use it. It is rather ridiculous if not humble. I'll update on how this project went after I use it. I may still try to paint the board green.

Happy Making!

Michelle