I stumbled upon this
18650 to 26650 Battery Converter Case Sleeve. Seems like it just makes a 18650 fit the larger compartment designed for 26650 without increasing its power? I didn't know different types of batteries could be interchanged in use. Could one do the similar to "convert" AAA's to AA's?
Edit: Ok, I think AAA is shorter than AA so it can't be done--but that's the only reason?
The only sleave I know of made for using a AAA in a AA battery slot is in a set of emergency supply sleeves. Reason for that is very obvious considering that AA batteries are the most common battery size of all and AAA batteries last half as long or less then the AA size and are just as expensive, so the only reason you would want to use a AAA in a AA size slot was in an emergency situation where you only had AAA size available which is still a stretch considering your more likely to AA available then AAA by mere statistical chance.
That said sleaves to use AA size batteries, especially NiMH recheargeables in the place of the larger C and D size cells are quite common and work quite well especially in the C size. Yes there are sleaves out there as well to use the more common but lower capacity 18650 cells in a 26650 size batter compartment if one so desires. And I even made myself a home-made adapter that uses a 123A size cell in place of one of those 3@AAA holders that are used inside some smaller flashlights.
Originally Posted by
leaftye
One really big factor that I didn't see mentioned yet is the risk involved with using lithium rechargeable batteries multi cell applications. Those devices are extremely unsafe when they're made poorly with bad parts. For those devices to be safe, they require cells that are very well matched regarding their voltage and internal resistance, and must still have good balancing charging circuitry and good protection as well.
With a single cell 26650 flashlight, that risk is eliminated.
The first thing I would do is avoid Ultrafire batteries. They are bad in virtually every way. Using them in a multi cell light is begging for disaster.
Next, buy cells that have been proven to work well. The King Kong 26650's are well loved. Also, this US-based supplier claims to be selling batteries with high quality cells, and they have protection as well. As you'll see in this link, I've bought some.
http://budgetlightforum.com/node/14761
Get yourself a multimeter and check your cells after rides to see how close you're coming to fully discharging them. This will give you a good idea of when you should swap cells during a ride. It's smart to check your cells during charging too to make sure your charger isn't over charging them, or at least do it until you can trust your charger.
If you discharge a cell too much and insist on charging it, charge it in a way that accounts for a fire, explosion and acid gas.
Personally, I prefer single 26650 lights above all others. Unfortunately there aren't many 26650 lights, and only one 26650 bike light. I'm currently running one 26650 flashlight and one 26650 bike light on my bike.
Yes, the potential dangers with LiIon batteries increase exponentially with the more of them you use in series without a quality battery control balancing circuit. The same applies to LiFePO4 batteries to a lesser extent, to NiCd batteries to an even lesser extent, and even applies to NiMH as well but only ever so marginally. The rule of thumb I have made up for myself personally is to never use more then - 2 unprotected LiIon cells, 4 protected LiIon cells, 4 unprotected LiFePO4 cells, 8 protected LiFePO4 cells, 8 unprotected NiCd cells, 16 protected NiCd cells, 16 unprotected NiMH cells, or 32 protected NiMH cells - in series without a quality battery managment circuit with balance leads connected to all the cross bar points in the pack. I call it my "two, double four, double eight, double sixteen, thirty-two" rule for building packs; and incase you are wondering you can purchase cross connecting bars with protection circuits built into them which is how you get protected cells from non-protected cells with LiFePO4, NiCd, and NiMH cells when they aren't sold in protected versions.
So long story short, yes, you are correct that since vol's light uses 1@26650 LiIon cell or 3@AA size NiMH cell for him to use a LiIon battery in his light would not have as much danger as using LiIon cells in a flashlight that used more then one LiIon cell in series especially if low quality unprotected cells were used. But using 3@AA NiMH cells will still be safer, especially for a beginner, then using 1@26650 LiIon.