Disposable e-cigarette Teardown - Part 1

I went for a lunch-time walk with the intention to look out for a discarded 'disposable' e-cigarette. I found by the side of the road almost immediately.

DANGER: 

There is a really good chance that the battery is still holding quite a lot of energy. The fluid runs out first. So if, during disassembly, the unit triggers (quite likely), then a big current will flow and the heating element will get hot. Similarly any accidental short between the leads to the battery could easily cause a fire.

Cut the leads to the element (one at a time) and to the battery (again one at a time) as soon as you can access them. 

Also have a contingency plan such as fire blanket (not a bucket of water) or open window through which the flaming device can safely be thrown in the event of it catching fire.

If in any doubt that you can do this safely, then don't do it.

This was quite a big one, and looking on the Internet sells for about £10 ($12). Far from being a flimsy thing, the case was well made and looked like it was designed to be taken apart. One end was held in place by push clips that opened easily with a screwdriver.

So what did I find! Well, a lot less than I was expecting! There are just 3 electronic components:

• The battery - 5.18Wh cylindrical LiPo. This was still measuring 3.4V
• The heating element - showing a cold resistance of 1Ω
• What looked like an electret mic insert, but I believe from the wiring, detects the cigarette being sucked, and switches power from the battery to the coil

There was no sign of any microcontroller or protection chip for the battery. The wiring is 0.4mm including insulation and not something that looked like it would cope with 3-4A. Hot wires and a heating element next to a LiPo cell - what could possibly go wrong!

Anyway, the battery is on charge and I'm pretty sure will come in very handy in some project or other.

I think it's a terrible waste of resources that these things are sold as disposable with insincere promises that they will be recycled properly. They aren't - people just drop them in the street.