3.7 V 3400 mAh 18650 Lithium-ion (Li-ion) cylindrical battery (NCR186504).
Panasonic is regarded as the most reliable 18650 battery brand. Used by most major laptop manufacturers for their battery packs. This battery is suitable for general portable electronic applications.
Li-ion batteries are much lighter than Ni-MH batteries. They also carry a higher voltage and offering better discharge curve.
