Battery knowledge well shared by pbsardo on his tasteyourjuice.com site

Read and take note of what will work best for your device and your safety.
-TasteYourJuice.com

A LITTLE ON BATTERY SAFETY

Difference in batteries:
In the electronic cigarette “mod” world there are two main types of batteries. ICR and IMR.
ICR = LiCoO2 (typical Li-ion)
IMR = LiMn

• It is generally accepted that IMR batteries use a safer chemistry than ICRs which is why ICRs can be purchased with and without protection circuits.
• IMRs can support higher discharge rates than ICRs (high drain) and are a better choice for lower resistance coils and mechanical devices.
• Although some ICRs have increased storage capacity (mAh) they may not always be able to deliver the amps requires to power your device. For example, this is why ProVape recommends IMR type batteries.

So if you want to be safe, what should you do? Here are some suggestions…

1. First, use any electronic cigarette or device AT YOUR OWN RISK!
2. Label/date your batteries so you know how long they’ve been in-use. If they’re still going after a year, toss them unless you have the ability to check their status.
3. Buy your batteries from reputable venders. I’ve been taken by the inflated mAh ratings seen on some “Ebay Offerings”. There are many good battery vendors out there. I get many of mine from RTD Vapor.
4. If you are using a protected device you should be ok with any battery selection. If not, use a safer chemistry IMR or “hybrid” and/or a mod fuse such as the 2 Cents For Safety fuse.
5. Get a QUALITY intelligent charger. The Xtars or Intellichargers both good choices. I personally useTHIS ONE and have never had an issue.
6. Do no over discharge your battery. When you’re battery approaches 3.3 volts, it’s time to charge.
7. Do not carry loose batteries. Batteries thrown in a purse or pocket could find metal and short. For example… keys! Exposed batteries have the potential to short when not properly protected.
8. Try not to stack, but if you MUST… 1) use protected batteries (unless your device doesn’t like protected batteries then see the following points), 2) use a fuse such as the 2 Cents For Safety if your device doesn’t have built in protection, 3) use a like pair, 4) your like pair should have been purchased at the same time… they are married. They like to be together and spend all their time together. So they want to be discharged (in the device) and charged (on the charger) together. Never stack unlike batteries, or like batteries of unknown condition.
9. If you’re into those ultra low resistance coils (which I don’t recommend BTW – I personally believe .8 ohms and up should be PLENTY good enough) KNOW YOUR BATTERY!!! Be sure that the battery is capable and rated to generate the amount of amps required by your setup! For example:

Setup 1 = 1 ohm coil with a loaded voltage of 4.0V (just an example). Using Ohms law, Amps = Voltage/Resistance = 4 Amp Draw. Easy for most batteries!
Setup 2 = .3 ohm coil (which I DO NOT recommend) with a loaded voltage of 4.0V (again, just an example). Using Ohms law, Amps = Voltage/Resistance = 13.3 Amp Draw. Can your battery support that?

A NOTE ABOUT C-RATINGS
The C-Rating of the battery defines the maximum draw (in amps) that the battery is capable of. To calculate the max amp draw you need the C-Rating and the mAh of the battery. For example a 2000 mAh battery rated at 10C would be:
Max Amp Draw = (mAh / 1000) * C-Rating
(2000 / 1000) * 10 = 20 Amp Max Draw

Note: Running your batteries at their C-Rating will decrease the overall life of the battery.
The C-Rating also indicates the amount of time the battery can support that discharge rate. A 1 C battery can support the calculated draw continuously for 1 hour. 2 C would be 1/2 of an hour. 10C would be 1/10 of an hour.