General Information: Batteries - Samlex Solar SCC-30AB Mode D'emploi

Battery Types
There are several different types of battery chemistries like Lead-Acid, Nickel-Iron
(Ni-Fe), Nickel-Cadmium (Ni-Cad) etc. The batteries consist of individual cells that can
be connected in series to obtain the required battery voltage. Batteries are either
sealed (also called Valve Regulated Lead Acid - VRLA) or non-sealed / vented / flooded /
wet cell.
Nickel-Iron (Ni-Fe) and Nickel-Cadmium (Ni-Cad) Battery
Nickel-Iron (Ni-Fe) and Nickel-Cadmium (Ni-Cad) (also called alkaline batteries) have
a nominal cell voltage of 1.2 volts per cell. The nominal voltage of a Ni-Cad / Ni-Fe
battery bank can be made the same as a lead acid bank just by juggling the number
of cells (10 cells for 12 volts, 20 cells for 24 volts and 40 cells for 48 volt systems).
However, the Ni-Cad / Ni-Fe battery bank must be charged to a higher voltage to fully
recharge and will drop to a lower voltage during discharging compared to a similarly
sized lead acid type battery.
Lead Acid Battery
A Lead Acid battery consists of a number of 2 V nominal cells (actual voltage of the
cell is 2.105 V) that are connected in series e.g. a 12 V nominal battery will have six,
2 V nominal cells in series (actual voltage of the 6 cells will be 2.105 x 6 = 12.63 V).
Each 2 V nominal cell in this battery consists of an independent enclosed compartment
that has Positive and Negative Plates (also called Electrodes) dipped in electrolyte
that is composed of diluted Sulphuric Acid – solution of 33.5% v/v Sulphuric Acid and
water. In a fully charged battery, the Positive Plate is in the form of Lead Dioxide, the
Negative Plate is in the form of Lead and the Sulphuric Acid in the electrolyte has the
maximum concentration of 33.5% v/v.
Electrochemical Reactions during Charging and Discharging
of Lead Acid Battery
Electrical power in the Lead Acid Battery is produced by reversible electrochemical
reactions as follows:
During discharging, the Sulphuric Acid in the electrolyte reacts with the Positive
and Negative plates resulting in conversion of the active materials in the two plates
to Lead Sulphate. At the same time, electrons are released that create the electrical
current that flows to the load. The concentration of Sulphuric Acid in the electrolyte is
reduced as the battery gets discharged (the electrolyte becomes pure water when the
battery is fully discharged).

GENERAL INFORMATION: BATTERIEs

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