How long can a battery last, and what chargers should I use?
Ideally, you want to use the compatible charger provided with the purchased kit, at all times. The reason for this is if a charger that is not compatible with the device is used, too much current goes into the batteries, meaning they can overheat and eventually stop functioning. Battery capacities vary from each device; they will indicate a mAh, which essentially is the battery capacity. Usually, after 6 months of use, the capacity within the battery starts to decrease, making the battery life last less.
We do recommend to charge the 18650, 20700, 21700 batteries with a portable charger like the Nitecore Intellicharger i4 Battery Charger