litium ion battery and tactical lights

Well here we go.
Most people have heard the wives tales about batteries.
1) You have to run the battery DEAD because it has MEMORY.
2) Leave it on the charger to keep it ready to use.
3) Re chargeable batteries don't last as long as single use batteries.
and many more.

Well these are the ones we will talk about today.
First. If you run your lithium battery dead there is a chance the two poles will swap creating a short when used with other batteries and cutting your run time and even make it possible to have a explosion. If you put a weak battery or a different kind of battery in a device there is a chance (pretty big) that the weak battery will heat up and cause the other batteries to either shut down or build up pressure and burst.
So when you put batteries in a device, make sure that they are well matched. If you are not sure, fully charge them and start over. If you are using single use batteries, you will need to use a multimeter and check the voltage.
Keep batteries as close as possible in voltage. I put them in baggies with a voltage to the .05volt marked on the outside so that I have matched sets. At Shows or demos I take the batteries out and put them aside for later.
Next if you leave the battery on the charger there is a chance that it will over charge and heat up. Heat is one of the hardest things on the batteries. If the battery gets too hot it can loose it's ability to re charge. At the least it will shorten the life span of the battery. They say that you should let the battery cool down before charging and let it cool off before re installing it in the device. This will produce a far better run time.
Lastly, if you get the re chargeable battery with a "mah" rating as close to the single use battery as possible. MAH stands for Milli Amp Hour rating. This tells you how much energy the battery is able to store. If you get a rechargeable with a mah rating of 750mah and the single use battery is 1400 mah then the rechargeable will only last aprox. 1/2 as long as the single use. If you get a rechargeable with an 1800 mah rating then you should get a longer run time out of the rechargeable . The main reason that most people get the shorter run time is the cost of a higher quality/higher run time battery can be quite different from the lower mah battery.
Also the quality of batteries is varies wildly. I have bee through a dozen different types of batteries trying to get good ones for my flashlights. Pricing can be from $3.00 to $25.00 for a CR123 rechargeable. Paying more does not mean that it is the best battery. some of the more reasonable batteries can be very dependable and have a good run time. The next issue is supply, Lithium ion batteries are prone to explode and most airlines have restrictions on transport. Some will not allow it at all.
Well I hope this helps, If you have any questions please let me know.
Thank you.
David