18650 is the founder of lithium battery---Sony corporation in order to save the cost to made the standard model of lithium battery. 18 means diameter of the battery, 65 means battery height, 0 means the battery shape is Cylinder. In the market, you will find two types 18650 battery, one is lithium-ion battery (Voltage: 3.6V/4.2V; Capacity: 2200mAh-3600mAh), the other is Lithium lron Phosphate Battery (Voltage:3.2V; Capacity: 1200mAh-3000mAh). In general, power bank manufacture use Lithium-ion battery for production.
1. High Capacity
18650 lithium-ion battery capacity is around 1200mAh to 3600mAh, normal battery capacity only has 800mAh. If combined them, the packing battery capacity can up to 20000mAh easily.
2. Long Serving Time
In general, the cycle time of normal use can reach 500 times. It is 2 times for the normal battery.
Incombustibly, non-toxic, no pollution. Through to RoHs certificated, temperature resistance. Under the 65°c, discharging efficiency can reach 100%. Can assemble protection board to prevent over-charge and over-discharge.
4. High Voltage
Normal voltage around 3.6V, 3.8V and 4.2V. Well above the average of nickel-cadmium battery 1.2V.
5. No memory effect
Don’t need discharge the battery to empty.
6. Can use in series and paralleling
When you know the power bank capacity and you know their battery cell is 18650, then you can calculate what the capacity of their battery cell.
1. Volume is fixed, cannot change the shape, and if you plan to develop the new power bank, if you choose the 18650 battery cell, your model shape cannot make big changes.
2. May have short circuit and explode easier, but this is relative to Polymer lithium battery. If you compare with the normal battery, this disadvantage is not so obvious.
Famous brand: LG, Sony, Panasonic, Sanyo, Samsung.
Chinese brand: Lishen, Bak, Zhuoneng
If you find the low retail prices power bank on online marketplace, believe me, their low-quality cell and have potential risk. Believe me, when you buy the goods, remember you got what you paid for.