Old RC Helicopter

I found this old RC helicopter in a box of electronics from when I was a kid and thought it’d be fun to see if I could get it running again, just to see if it still worked. The remote had no batteries, and I vaguely remembered doing something to the copter back then, but couldn’t recall what exactly.

I took it apart and saw that kid me had installed one of those 3V lithium CR2032 batteries in the helicopter. This was before I knew much about electronics, so I kind of get why I did that. I knew the helicopter ran on 4.2 volts, and those little lithium batteries are 3 volts, so my logic back then was probably: “Meh, close enough.”
Spoiler: It wasn’t close enough. lol

I was trying to decipher what I had done and realized I must’ve assumed “lithium” meant “rechargeable”—which those CR2032s definitely aren’t. But they’re small, 3V, and seemed like a good fit, so I soldered wires to one, hot-glued it for stability (you can see it in the pics), and placed it where the original battery went. I can’t remember if it actually flew, but I’m guessing it didn’t.

Now that I know a bit more about how this stuff works, I decided to power it using a lithium cell from an old vape. It’s a 300mAh battery, and it actually works! A cool thing about these vapes is they usually come with a USB Type-C charging port for the battery, so I can now charge the toy using a regular phone charger.

Next challenge: the controller.
Well, not really a challenge—it just uses 9 volts (six 1.5V AA batteries). I have lithium cells, so I figured I could make it rechargeable. Two fully charged 21700 cells in series give me 8.4V (4.2V each), which should be enough. If not, I could try three slightly discharged ones to get closer to the full 9V.
Now that I’m writing this, I realize I could’ve just used an actual 9V battery… but I wanted it to be rechargeable, and lithium is the way to go in my opinion.

It works.
I honestly didn’t think it would, considering how long it’s been. But really, there’s no reason it wouldn’t work. I’ll probably give it to my little sister to play with, since it was just a fun little project I wanted to try. And I’m honestly impressed I had all the stuff to actually make it happen.