I've mentioned in the past that I like to refurb old electronic devices that use rechargeable batteries. Don't you hate throwing away something that needs a proprietary Nickel Metal Hydride battery from the manufacturer that exceeds the replacement cost of a new unit? Here is an example.
Futaba airplane radio from the 80s. Used nicad batteries that died and leaked long ago. The replacement pack costs a fortune because it's made by cottage industries that exist to keep vintage RC stuff going.
![Image](https://c5.staticflickr.com/6/5547/30719348756_8e12069e31.jpg)
I'm not a purist so I don't care if it isn't original Futaba anymore. I just want to control some robotics projects with the radio. So this is what I do. Three Li cells approximately match the voltage of the umpteen nicads it used to have.
![Image](https://c1.staticflickr.com/6/5642/30639404512_d9bf96458b.jpg)
I go to ebay and buy one of these 18650 Li Ion battery clips. Its like a AA holder but bigger. Costs $1. Double stick tape it to the back of the radio. Solder +/- wires between the radio and the battery clip.
I salvage some 18650 batteries from old laptops. But you can also buy them for less than $2 each. Once you use these, you'll wonder why everything AA powered isn't designed with 18650. AA should be made illegal. 18650 will hold 75% of their charge for over a year on the shelf. The number of recharge cycles they take puts nicad to shame. They also have a high energy density and can source a lot of current. Junk batteries can be found in all kinds of stuff. Just start tearing stuff up. Kindles have nice batteries too. You just have to unwrap them and solder wires to the cells. (use common sense, shorted cells can blow like a Samsung phone!)
![Image](https://c1.staticflickr.com/6/5518/30455531600_3b644405a9.jpg)
Motorola spirit walkie talkies for when the cell grid goes out. Useful where there is little cell reception. The proprietary motorola battery is crazy expensive and it dies after a year of use. So I do the same old trick.
![Image](https://c5.staticflickr.com/6/5511/30455535140_b4f813451f.jpg)
Here's a toy car that I converted to laptop batteries. See the white pigtail in the front of the battery pack? That's the charge cable. You can buy those pigtails by the dozen on ebay for dimes. It's a standard balance connection used by RC car people and connects to standard cheap chargers.
![Image](https://c3.staticflickr.com/6/5594/30639388202_5081208113.jpg)
Getting the idea?
How about charging? Ebay again. Lotsa different kinds of LI Ion chargers out there.
These: (good for simplicity) $2
![Image](https://c7.staticflickr.com/6/5817/30639399662_6631dfc02a.jpg)
These: (good for multi cell balancing) $2
![Image](https://c3.staticflickr.com/6/5506/30455539370_c867e9bc0b.jpg)
These: (common for model helicopters) $2
![Image](https://c5.staticflickr.com/6/5527/30719373276_3dc0973e34.jpg)
They even sell these high power LED flashlights that use recycled laptop cells. I've fully converted at my home. No more AA battery lights. Those should be made illegal. This brown flashlight only costs $5 shipped. Blinding brightness and a two hour burn time on free batteries.
![Image](https://c5.staticflickr.com/6/5506/30639394852_463f42fd0b.jpg)
This is a neat freebee given to me at a tradeshow recently. It is a LI battery in a little box with a USB input and output to act as an onboard charger and power supply for a phone. So you can charge this on a PC then use the power to power up a bike light for example. These chinese wonders are dang near free online. So you can make your own rechargeable devices with one of these and a scrap of old USB cable.
![Image](https://c7.staticflickr.com/6/5637/30455501870_90b2acba39.jpg)
Next time you trash a dead iphone remember that there is a nice battery still in there. Strip all your ewaste. Don't give it to some third world sweat shop. Cherry pick it first.
![Image](https://c5.staticflickr.com/6/5487/30719376956_bddfcce2f1.jpg)
Have fun. And be careful. Charging LI batteries incorrectly can start fires. Shorting LI batteries can cause explosions. The batteries contain Li and an extremely flammable electrolyte = Molotov cocktail the size of a grenade. Do your Youtube research first if you are uninitiated. Watch what happens when you poke a pin through the electrode. I like to charge the batteries in a metal ammo can to contain a spontaneous explosion. (It's actually scary we do this same thing with our phones regularly without a thought). With great power comes great responsibility.