We are stocking batteries from GP Battery, Panasonic, Sanyo, Coolook, Samsung and Spark.
The AAA and AA Recyko batteries are the same as Eneloop batteries. They are rechargeable 1000 times. They do not have the high self discharge rate of standard NiMh so they are more suitable for use in Radios and Headlamps. This is the preferred cell for the Wouxun AA Cell battery pack, and the Spark SD series,the SL5, and SX5. See review.
The 18650 Li Ion batteries come in protected and unprotected versions. Protected batteries have a built in protection circuit and uprotected do not. So the utmost care must be taken when using the unprotected verions. They should never be used in devices in series because differences in internal resistance can cause venting and lead to fire or explosion. They need to be monitored when charging and charged properly. Whether you are charging a protected or unprotected Li-Ion cell, you should always be in the same room during the entire charge cycle and monitor from time to time. If you see smoke or smell anything unplug the power bar that the charger is plugged into and leave it to cool before touching the battery. The charger should be of high quality.
LiFePO4 cells are the newest battery chemistry and come in all formats. Because they are 3.2v nominal (3.6v fully charged), one of them apired with a dummy cell, is a good replacement for 2 AA or AAA cells. They are growing in popularity because they are very safe, are very light, have a good duty cycle (lots recharge cycle capabilities), and good cold temperature performance
Primary Cells are batteries you use once and then recycle, such as AA Alkalines for example. Their prime function for our clients would be as emergency backup cells to be carried in your glove box or day pack, or for very cold weather (below -20c). If using Li-Ion for a radio, the problem can be mitigated by keeping it under clothing, for headlamps the problem can be addressed by using a light that allows the battery to be kept under clothing such as the Spark SX5 option battery pack..