As a newcomer to flashlights, I found it an extremely steep learning curve to get all the information I needed. I was frequently directed to hard-to-follow info pages on all kinds of stuff; some of it was worth reading, some of it was a complete waste of time (for me).
This guide will give you the basics. The stuff in bold is stuff you NEED TO KNOW to operate an 18650 flashlight safely. Other information will be provided to help explain the stuff in bold in case you have any questions. Links will be provided at the bottom for those who wish to do some more research.
WHAT YOU RISK is literally life, limb, and home, if you choose to ignore these guidelines.
Preamble (skip if you like, but it may come in handy when reading):
What are these suckers, anyway? What’s the big problem; why can’t I just pick up some cells and start using my flashlight? Good questions! It’s probably easiest to understand if we consider what they’re NOT. What they’re not, is is a cell made for your average consumer. These cells have higher energy density, which is both their attraction and the cause of safety concerns. While the technology has come a long way in terms of safety, and a huge number of flashoholics use these cells safely, there’s enough of a safety concern that companies like Panasonic and Sanyo, who are the ACTUAL manufacturers of these cells, refuse to market them directly to the public. The manufacturers only sell these cells to other manufacturers, who must meet the primary manufacturer’s safety guidelines for their use.
So with that in mind, how do we end up with nice little cells for use in our flashlights? Another good question. The answer appears to be that other companies acquire them somehow, and repackage them as individual cells for use in things like flashlights. Of course, there are many ways a company might acquire cells. These cells are often used in things like laptop batteries. One way to acquire cells is to buy refurbished laptop batteries at huge discounts, rip them open, and salvage the cells that aren’t dead yet.
The problems with buying such cells are the similar to the problems one faces when buying a second-hand car. We don’t know how the cells have been used in the past, how much life is left in them, or if the darn things have some sort of internal problems that make them ticking time bombs. Obviously, these are not the sort of cells we’d prefer to buy, since we have no idea what we’re getting.
The reason we can’t (or shouldn’t) just blindly buy and start using without doing research, is that, under certain circumstances,
18650’s can do the following:
# Explode, turning your flashlight into a pipe bomb
# Vent toxic gas
# Start a fire that is extremely difficult to extinguish.
These are worst-case scenarios, and highly unlikely. Highly unlikely, that is, if one follows the guidelines in this guide to the best of one’s ability.
edit: as a result of improvements in safety, these primary cells are starting to make an appearance in more mainstream consumer outlets. There is, however, in the opinion of some (many?), including myself, still a place for a guide such as this.
ALWAYS EXERCISE COMMON SENSE when handling these cells; i.e., don’t try to damage them, burn them, short them, etc… If something unusual has happened to the cell, don’t use it in any way without first asking someone in the know.
A digital multimeter, or some other means of accurately taking voltage measurements, is a MUST-HAVE when using these cells. Knowing the voltage of a cell will tell you when it needs to be charged, when it’s no longer useable, when your charger is misbehaving, help diagnose problems with your flashlight, help determine when cells have become unsafe to use, and allow you to use multi-cell flashlights safely.
Before connecting your cell to anything, you should always inspect it physically for signs of damage. This includes:
1. Discoloration (signs of overheating)
2. Tears in the wrapper
3. Signs of deformation (not perfectly cylindrical anymore)
The rule, “If in doubt, leave it out,” should apply here. Bring it to the attention of someone with more experience if you have any concerns or doubts.
Before installing cells in a flashlight, or charger, always check the voltage.
voltage should read between 2.5-4.2V (some specific types of cells can be charged to a higher voltage)
Cells with a voltage lower than 2.5 should be discarded safely, according to the regulations for waste disposal in your country.
Under no circumstances should you try to charge these cells or use them in your flashlight.
[It’s been months of lurking, and I now feel reasonably comfortable having a conversation about the technology, although I still have tons to learn. But now my friend, having been impressed by my flashlights on our camping trips, is interested in picking up lights and cells. I know he has no idea what he’s getting himself into, and I always find myself tied in knots trying to explain things to him.
I was thinking this forum could benefit from an idiot’s guide to 18650’s. I don’t think I’m qualified to write it… at least not without some serious help from the forum. On the other hand, I have the time, interest, and an idea of what sort of info I’d like to include, and how to organize it.
My question is, do you guys think it’d be worth doing? Is there anyone who wants to take up the project? Or could I start an open-source kind of thread, where I post something and people can post replies when I get it wrong. Then, when it’s more-or-less finalized, have it as a sticky.