The 18650 battery typically has a power of 3.7 volts and a current of 2600mAh. An overwhelming number of 18650 types are rechargeable. This feature should become the uniform standard moving forward.
Kriya Yoga is a simple, psychophysiological method by which human blood is decarbonated and recharged with oxygen. The atoms of this extra oxygen are transmuted into life current to rejuvenate the brain and spinal centers.
This is particularly true with the practices dealing with the spinal energy and the vigorous practices. The breathing and pranayama practices may be known collectively, or considered to be part of pranayama alone, hatha Yoga, raja Yoga, kundalini Yoga, kriya Yoga, tantra, or simply Yoga.