Batteries are an excellent source of portable power, and are literally everywhere. Since the invention of Lithium-ion batteries in the 1970’s, their overall usefulness has grown leaps and bounds! Their ability to provide a higher current, plus being able to store higher amounts of energy, makes them very desirable for energy hungry applications. But, there are downsides.
Shapes and sizes
Just like humans, lithium batteries are made to be uniquely different from each other. Your cell phone uses the flat, square variety. Many digital cameras use them too (including the model I own).
Other devices find these batteries useful as well, including power tools, electric shavers and a massive variety of handheld LED flashlights.
If you’re wondering why lithium batteries have strange numerical names, it’s because of their size.For instance, a 16340 cell is 16mm x 34mm. The zero at the end refers to its cylindrical shape. From that, it shouldn’t be too hard to imagine why a 18650 is so-named.
Laptop computers are perhaps one of the more well known consumer items that utilize 18650 batteries.
Aside from a camera, about the only device where a consumer actually “handles” the bare cell, or needs to charge it manually, is the LED flashlight. More on that handling process in a bit.
Be Informed Before You Buy
This section is devoted to advertised capacities.
With a 18650 cell, most of what you see in probably pretty accurate. About the smallest capacity you’ll see is around 2200 mAh. These days a 18650 can deliver up to 3400 mAh quite comfortably. The higher the capacity, the longer they’ll run before needing a charge.
Where capacities don’t always say what they mean is with either a 16340 or a 14500. With these batteries, the most power you’ll usually get is 750 mAh. Some are less than 750. Many Chinese marketers will often attempt to falsely raise the claims on these particular cells. Some might be sold as 800 mAh. Some are sold as 900 mAh.
I can tell you from experience, that I bought four 16340’s a few years back, at 900 mAh each. They are the poorest performing of all the batteries I own! They discharge very quickly, and won’t charge much above 4.10 volts. One thing IS for sure, if (or when) you see any 14500, or 16340 cells with an advertised capacity as high as 1000 mAh…move along. This is pure hype, and not only that, the batteries won’t perform any better than those labeled as 750 or 800 mAh. There’s also the possibility that their actual capacity is much LESS than 750 mAh!!
Good quality 18650’s can be found at this link!
The Advantage of Li-ions
As mentioned in the last paragraph, their varied shapes allow greater versatility.
They have no “memory effect”. This means that they’re not bound by any particular charging rituals, meaning they can be charged more frequently without the cell always depleting at the same interval. As an example; think about the number of times your cell phone will be charged, with the state of “charge” being slightly different each time.
When compared to other rechargeable types, such as nickel metal hydride (NiMH), li-ion cells have a much slower self-discharge rate. They’ll typically only lose about 5 – 10% per month. As a side note though…some NiMH cells are specifically labeled as ‘low self-discharge’ – actually discharging at a lower percentage than the lithium cells!
Are There Any Disadvantages?
Yes. As with ANY battery – eventually they’ll wear out.
To explain further, the charging cycles leave internal deposits, which over time diminish the cell’s effectiveness and its ability to hold a full charge. Air temperature plays a part as well. Charging in extremely hot conditions can shorten its life. What about cold? Lithium-ion cells are not typically affected as much by extreme cold as standard batteries are. For example, a lithium primary (non-rechargeable) AA size battery, will work well in an all-season outdoor device. Meanwhile, a standard alkaline AA cell, might become weak and ultimately fail if used in the same device, under the same conditions.
Are Lithium Batteries Dangerous in Any Way?
Yes. BUT, ONLY in specific situations.
Mishandling of a lithium cell can include something as simple as using them in a device where more than one cell is required, but owning several of the same batteries and mixing them up. In other words; there’s nothing wrong with owning several, but mixing them so that you’re using pairs that are of uneven voltage, is not.
Here’s an example; Two batteries complete a charge. One of them finishes between 4.09 and 4.12 volts. The other ends up closer to 4.20 volts. Ideally, it’s not recommended that these two cells be paired in a device together. Their ending voltage should be closer to each other. So, in a worst case scenario, this could be dangerous. Just use common sense precautions, and most disasters can be completely avoided.
When owning rechargeable cells, it’s important that you also buy a multimeter capable of displaying active current for Li-ion cells. This way, by testing the “live” status of a battery prior to charging, or for use, you’ll know whether it’s safe to pair with a similar cell. Knowledge, when using lithium batteries is key!
Other precautions include – never over charging or over DIS-charging a lithium cell. Buying only “protected” cells will take this obligation out of your hands. This means that the battery itself will shut down when the voltage gets too low – usually at 3.0 volts. The circuit will also protect it from charging over its upper threshold as well – which is normally 4.20 volts. Just look for the term “protected” when purchasing Lithium-ion batteries.
Your questions or comments on Lithium-ion batteries are most appreciated!