Carlagamer:
Most of the flashlights being discussed are powered by li-ion batteries.
Are you familiar with the hazards posed by them? (Fire, explosion, fumes, eco-waste, single cell vs. multi-cell applications.)
http://www.candlepowerforums.com/vb/showthread.php?280909-Ultrafire-18650-3000mA-exploded http://www.candlepowerforums.com/vb/showthread.php?340028-Flashlight-Explosion
18650, how dangerous is it for a newbie like me?
My 14500 battery explosion, with pictures
Light catches fire burns house down
Are you aware of safe practices for using them? (Charging, discharging, storage, general care.)
A Litany for Beginners:
1. Buy quality batteries and chargers. How do you know what is good quality and what is bad quality?
- Research the internet. A good starting point is this website: Batteries and chargers (the author, HKJ, is a frequent contributor here).
- Buy from a trusted vendor who sells only high quality products, such as RMM (Richard, the owner, is a respected BLF member).
- Or simply ask questions on BLF.
2. Discharging. Avoid over-discharging your batteries. Your regular li-ion battery is nominally rated at 3.7V, but that’s only a rating. It actually varies between 4.2 (fully charged) to 2.7 (fully discharged).
- When using your batteries, learn about their charge state by checking with a voltmeter (or with your charger if it is so equipped) whenever you recharge the batteries. I’d recommend targeting 3.5V as the level when to recharge, with 3.0V being “acceptable”. Lower than 3.0V and you’re doing some (slight) damage to your batteries. Lower than 2.7V and you are definitely hurting your batteries. If you ever hit 2.5V or lower, you should be very careful whenever you recharge and use this battery.
- If you have no means of measuring the batteries’ voltage, then the next best thing is to recharge your batteries as soon as you notice the flashlight output declining. Get into the habit of recharging your batteries on a regular basis.
3. Charging. A good quality charger will help prevent overcharging. On the better chargers, digital readouts help you to keep track of the charging process.
- Never charge your batteries when you are not present. While it’s not necessary for you to hover over them while they are recharging, you should be alert and close enough to respond to any problems.
- Periodically check them to see if they are getting hot, especially if they seem to be taking a long time to recharge. (Depending on charge rate, they may get warm, but they should never get hot.)
- If you need to leave while your batteries are still charging, pull the batteries out and re-start the process when you return.
4. Care and maintenance.
- Avoid physical abuse.
- Avoid getting the batteries wet.
- Discard any dented, deformed, or punctured batteries. Properly dispose of them as eco-waste.
- When not being used, store them in a cool, dry location.
- When storing them for long periods of time, store them at 70% or about 3.5V-3.7V.
- When storing them, make sure that there is no possibility for short circuits. Ensure that there is no way for any loose metal (or jumble of loose batteries) coming into simultaneous contact with both terminals of any battery.
5. Multiple cell applications. Understand that your risks go up exponentially by using multiple cells. Not only do your chances increase and the potential magnitude increase by the number of batteries being used, but the risks of unbalanced discharge between batteries is introduced. So all the caveats of using single cells are even more important: don’t overcharge, don’t over-discharge your batteries, and take care of them properly. In addition, the following guidelines have been suggested:
- Use mated sets of batteries. Use the same brand and specific model of battery within a set.
- Always keep the same set for the flashlight. Don’t mix and match batteries when recharging.
- Always recharge all of the batteries at the same time. Don’t partially charge individual cells.
6. Protected cells versus unprotected cells. Protected cells have circuitry that provides safeguards against overcharging (usually set at 4.2 volts) and over-discharging (set at somewhere between 2.6V to 2.9V, depending on manufacturer). Do not depend on the protection to work. While they are fairly reliable, they are not foolproof. Consider them as a fail-safe device or measure of last resort.
Other things that you should know:
- Protected cells are slightly longer than their unprotected counterparts. Most flashlights can accept either, but some have such tight margins that only unprotected or smaller models of protected cells will fit.
- Protected cells, because of their additional circuitry, are limited in providing maximum power. For most flashlights, this does not make a difference, since the flashlight driver is the limiting item in providing power to the LED. However, for some of the newer flashlights, the drivers are direct driven and the limiting item is the battery. Unprotected high-drain cells are recommended for such flashlights.
- The protection circuit is sometimes referred to as PCM or PCB (Protection Circuit Module or Protection Circuit Board).
- Besides protected and unprotected types of batteries, batteries may come in either button-top or flat-top versions. Button-tops are the more common variety and fit almost all flashlights. Flat-tops are suitable for single cell flashlights that have both head-springs and tail-springs. If you plan on buying flat-tops, make sure that they will work for your particular flashlight.
7. Low Voltage Protection (LVP). Some flashlights are equipped with LVP circuits to prevent the overdischarge of batteries. Depending on the specific manufacturer, the LVP circuits may cut off the battery between 2.6V and 3.0V. In some cases, the LVP circuit may merely warn the user about the low voltage by some sort of flashing mechanism - while allowing the battery to continue to drain well below the warning level (down to zero in some cases). Again, similar to the battery protection, it is recommended that you not rely on LVP to prevent over-discharge of batteries.
8. Sizes and Types of Li-ion Cells.
- There are different sizes of li-ion cells. The first two digits represent the diameter in millimeters. The next two digits represent the length in millimeters. Hence, a 10440 cell (about the size of a AAA battery) is 10mm wide by 44mm long. A 14500 cell (about the size of a AA battery) is 14mm wide by 50mm long. The last “0” at the end of the 10440 and 14500 represents the shape of the battery, i.e., circular in shape. Note: These are nominal dimensions, some so-called 18650 batteries are actually over 70mm long!
- There are a number of different types of cells that are referred to as lithium-based batteries. It is customary to distinguish “lithium” batteries as those primary (non-rechargeable) 3.0V batteries, “LiFePO4” batteries as the rechargeable 3.2V-3.3V batteries, and “li-ion” batteries as the rechargeable 3.7V batteries. And within the set of so called “li-ion” 3.7V batteries, there are several different chemistries: LiCoO2 (ICR), LiMn2O4 (IMR), LiNiMnCoO2 (INR), hybrid of other chemistries (NCR).
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This is just a brief overview to get you acquainted with the subject of li-ion cells, what they are, and how to treat them.
For the two flashlights that you are interested in, the BLF A6 and the Convoy C8:
- Both of them take 18650 cells.
- Both have head-springs and tail-springs, so they both can take flat-top batteries (button-tops, too).
- Both use single cells, so you avoid the multi-cell complications.
- The BLF A6 has an FET driver so is capable of being directly driven. For maximum output, it’s recommended that you use an unprotected high-drain cell like a Samsung INR 18650-30Q battery.
- The Convoy C8 is not directly driven. There’s no advantage to using unprotected cells with it.
Buy good quality stuff, be aware and alert, and act with due diligence.
That’s the formula for staying out of trouble.