Samlex Solar SCC-30AB Mode D'emploi page 18

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GENERAL INFORMATION: BATTERIEs
The holes in the grid of the plates are filled with a paste of active material made
out of a mixture of Red Lead and 33% dilute Sulphuric Acid (different manufacturers
use modified mixtures). The paste is pressed into the holes in the grid. This paste
remains porous and allows the Sulphuric Acid in the electrolyte to react with the
lead inside the plate increasing the surface area many fold. At this stage, the Positive
and Negative plates are identical. Once dry, the plates are then stacked together
with suitable separators and inserted in the battery container. After the electrolyte
has been added to the cell, the cell is given its first "Forming Charge". During this
"Forming Charge", the Lead paste in the Positive plate gradually turns to Lead
Dioxide (chocolate brown color), and the Lead paste in the Negative plate turns to
Sponge Lead (slate gray color). Such charged cell is ready to be used.
The above grid structure of the plates is made from a Lead alloy. A pure Lead grid
structure is not strong enough by itself to stand vertically while supporting the active
material. Other metals in small quantities are alloyed with Lead for added strength
and improved electrical properties. The most commonly alloyed metals are Antimony,
Calcium, Tin, and Selenium.
The two most common alloys used today to harden the grid are Antimony and
Calcium. Batteries with these types of grids are sometimes called "Lead-Antimony"
and & "Lead-Calcium" batteries. Tin is added to Lead-Calcium grids to improve
cyclability
The major differences between batteries with Lead-Antimony and Lead-Calcium
grids are as follows:
• Lead-Antimony batteries can be deep cycled more times than Lead-Calcium batteries.
• Flooded Lead-Antimony batteries require more frequent maintenance as they near end-of-
life since they use an increasing amount of water and require periodic equalization charges.
• Lead-Calcium batteries have lower self-discharge rates and therefore, will draw less current
while kept in storage
SLI (Starting, Lighting, Ignition) Batteries
Everybody is familiar with the SLI batteries that are used for automotive starting,
lighting, ignition and powering vehicular accessories. SLI batteries are designed to
produce high power in short bursts for cranking. SLI batteries use lots of thin plates
to maximize the surface area of the battery for providing very large bursts of current
(also specified as Cranking Amps). This allows very high starting current but causes the
plates to warp when the battery is cycled. Vehicle starting typically discharges 1%-
3% of a healthy SLI battery's capacity. The automotive SLI battery is not designed for
repeated deep discharge where up to 80 % of the battery capacity is discharged and
then recharged. If an SLI battery is used for this type of deep discharge application,
its useful service life will be drastically reduced.
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