E-cigarettes use electrical power to rapidly heat and vaporize a base liquid such as propylene glycol, and that power comes from a battery. These devices are functionally straightforward but it can be a messy process on the inside. Thankfully though the batteries can be salvaged once components like heating elements either gum up or burn out.
[facelesstech] decided to use the battery from an e-cig as the power source for a smart sunglasses project, which uses two RGB LED rings to put on a light show. Opening up the device it was discovered that the battery was a straightforward lithium-polymer cell, in AAAA size. If you’ve ever torn open a 9 v battery and discovered the six diminutive cylinders inside, an AAAA cell is about the same size as one of those. However, the battery from the e-cig is both rechargeable and has a nominal voltage of 3.7 volts, which can happily drive a microcontroller project. The small battery fit nicely into one arm of the glasses, and when covered with heat-shrink, was hardly noticeable. The battery charger doesn’t fit inside the glasses, but one can’t have everything.
The ability of an e-cigarette to pump out clouds of vapor has led to some interesting hacks. One such is a DIY portable fog machine, which opens all kinds of doors for costuming applications.
Humans like things that look like other things. A great example are faux LED tea light candles, with a plastic “flame” and flickering orange LED to recreate the effect of their waxy brethren. [gzumwalt] wanted to take the concept a little further, however, and got down to work.
The design harvests the orange LED and flame lens from an existing LED candle, but the rest is all original. [gzumwalt] printed a full-size candle, and fitted it with inductive charging hardware and a lithium-polymer battery. A corresponding charging base is used to supply power to the candle when it’s not in use. This is all handled automatically, with neodymium magnets used to activate reed switches to turn the charger on and the LED off.
It’s a tidy build that can be easily replicated with a 3D printer and some off-the-shelf parts. It’s also less wasteful than using disposable batteries, and safer than using real candles – so if you find yourself routinely shooting candle scenes in your budget film studio, it might be worth printing up a set of these.
[Glen], at Maker Space Newcastle Upon Tyne, is refreshingly honest. As he puts it, he’s too cheap to buy a proper battery.
He needed a 1AH battery pack to power his quadcopter controller and FPV headset, and since inadequate discharge warnings had led him to damage lithium polymer cells with these devices, he wanted his pack to use lithium-ion cells. His requirements were that the cells be as cheap, lightweight, and small as possible, so to satisfy them he turned to a stack of mobile phone cells. Nokia BL-4U cells could be had for under a pound ($1.46) including delivery, so they certainly satisfied his requirement for cheapness.
It might seem a simple procedure, to put together a battery pack, and in terms of physical wiring it certainly is. But lithium-ion cells are not simply connected together in the way dry cells are, to avoid a significant fire risk they need to have the voltage of each individual cell monitored with a special balanced charger. Thus each cell junction needs to be brought out to another connector to the charger.
[Glen]’s write-up takes the reader through all the requirements of safe lithium-ion pack construction and charging, and is a useful read for any lithium-ion newbies. If nothing else it serves as a useful reminder that mobile phone cells can be surprisingly cheap.