There are 2 types of AA-size batteries


Group A Output=1.2-1.5V:  

  • 1.5V Alkaline AA (your everyday Duracell or Energize), Non-rechargeable
  • 1.5V Lithium-ion AA battery (Duracell or Energize,), Non-rechargeable
  • 1.2V Ni-Mh rechargeable (The most common one is Eneloop. we have a similar one called Enelong). Rechargeable through most Nitecore chargers (unless the charger is specified as Li-ion only such as the UM10/UM20)
  • 1.5V Lithium-ion rechargeable battery with USB port (Fenix ARB-L14-1600 is the only model here. It can only be charged through a USB cable but not through external chargers)

These batteries are interchangeable.


Group B: Output=3.7V

  • 14500 lithium-ion rechargeable such as NL1485, NL1475R, Fenix's ARB-14-800
  • IMR14500, Nitecore NI14500, a version of 1) without the protection circuit

Group B is not interchangeable with group A. Therefore we call them "3.7V 14500 rechargeable batteries" rather than "AA rechargeable batteries". The IMR14500 is used to drive high drain electronics such as Nitecore MT10A or some vapor devices.  But it is easily over-discharged because of its lacking of protection circuits therefore we don't usually recommend it unless the buyer knows what he is getting/doing.


Applications: 


Some flashlights are designed to operate under voltages from 1.2V up to 4.2V. So they can take either A and B. With a higher output at 3.7V, B will increase the flashlight output and make it brighter. 


Some flashlights are designed to operate under 1.5V. A 3.7V battery in group B will burn out the circuits.


Some flashlights are designed to accept A but can also tolerate B. It is called "overdrive". The light will only have the brightest setting available but losing all dimmer settings when using a 3.7V B battery. We usually do not recommend that.

 

Therefore when a buyer asks for a "Rechargeable AA battery", it is important to learn the output voltage (or the model) of his original battery so we can recommend a compatible model from group A or B.

  • If the buyer is using a 1.5V AA battery and looking for a rechargeable type, recommend a Ni-Mh rechargeable or the Fenix ARB-L14-1600 if he does not mind using a USB cable to charge the battery directly.
  • If the buyer's device can take 3.7V, recommend the batteries in group B, either the NL1485 or NL1475R, depending on how he plans to charge them.
  • Recommend the Nitecore Ni14500A (only) if the buyer is looking for an IMR14500 battery