SMAC-Based WSN Protocol-Current State of the Art, Challenges, and Future Directions

Table 1

Comparison of battery chemistries used in WSNs (adapted from Battery University [30]).

Battery chemistry	Energy density (Wh/kg)	Cycle life	Cell voltage (nominal)	Capacity (mAh)	Operating temperature (°C)	Pros	Cons
Alkaline	80 (initial)	50^3	1.5	Varies	0 to 65	High energy density, cheap,	Heavily affected by load, heavyweight, high internal resistance
Li-ion	110–160	500–1000^3	3.6	730	-20 to 60	High energy density, low maintenance, low self-discharge	Expensive, not fully matured
LiPo	100–300	300–500	3.6	930	0 to 60	Flexible form factor, lightweight, more resistant to overcharge	Expensive, low energy density, decreased cycle count
NiMH	60–120	300–500^2,3	1.25^6	2500	-20 to 60	Simple storage and transportation, environmentally friendly, less prone to memory	Limited service life, high self-discharge, longer charge time