一、 the chemical power supply
1. Primary Battery
Once a way to convert chemical energy into electrical energy devices. Such as: manganese - zinc batteries, silver - zinc batteries, silver and magnesium battery and so on belong to this category.
2. Rechargeable battery
A way to achieve the chemical energy and electrical energy freely switch between devices. Such as: lithium (ion) battery \ Ni-MH battery \ nickel-cadmium batteries and lead-acid batteries are in this category.
3. Fuel Cell
Will be a way to continue to chemical energy is converted to electrical energy. Such as: zinc fuel cell \ methane, hydrogen fuel cells and fuel cells fall into this category.

. Characterization of the battery energy capacity is an important indicator of
. Capacity unit: coulomb, mAh, Ah, etc.
. Formula: Q = I * t
. Conversion method: 1mAh = 3.6 Coulomb
1Ah = 3600 coulomb

Characterization of the battery voltage is another important indicator of energy
Unit: volts
The existence of a secondary battery for the average working voltage of concepts (discharge voltage is not a fixed value)

Characterization of cells within the Yin is the internal resistance generated by the current size of the target
Unit: Ω, mΩ
Resistance surface area, set to wait until the fluid connection.

Characterization of specific energy is the energy density of the battery indicator
Than the energy is generally divided into: the mass ratio of energy (Km) and the volume ratio of energy (Kv) two kinds of
Km = W / M = Q * U / m (average for the secondary battery voltage U)
Kv = W / V = Q * U / V (for the secondary battery voltage U for an average)
Manufacturers produce the same battery model due to a variety of specifications, capacity will vary, but in terms of specific energy is almost a more stable constant.