SAMLEX AMERICA INC. | 21
1.4.5.2 Rise / fall in the temperature of the electrolyte with respect to the Standard Room Temperature of 77º
F / 25º C will require temperature compensation. Charging voltages will be required to be reduced at higher
electrolyte temperature and increased at lower electrolyte temperature with respect to the Standard Room
Temperature of 77º F / 25ºC. If charging voltages are not temperature compensated, the battery will boil / be
overcharged during higher temperatures and under charged during lower temperatures. This will result in reduced
battery life / damage to the battery. It is, therefore, desirable that a temperature compensated battery charger
is used if the Room Temperature swings more than 7º F / 5ºC. Temperature compensated battery chargers are
provided with either internal or external Temperature Sensor.
1.4.5.3 Effects of Over Charging: Over charging will lead to excessive amount of decomposition of water into
Hydrogen and Oxygen and generation of excessive heat. As the battery electrolyte temperature rises, the battery
charging voltage is required to be reduced. However, the charger voltage will not reduce in a charger that has no
temperature compensation. This condition will drive more current and ,therefore, heating up the electrolyte even
further. This is called “thermal runaway” and may damage the battery within a few hours:
• Flooded battery will lose water / shed pasted material.
• Sealed battery will see rise in internal pressure as the rate of generation of Hydrogen and Oxygen will be
more than the designed rate of recombination provided by the Recombinant Catalyst. The battery casing
will bulge excessively and the pressure release valves may open.
1.4.5.4 Effects of Under Charging – Sulfation: Refer to Section 1.4.4.1 for details.
1.4.6 Self Discharge Of Lead Acid Batteries:
1.4.6.1 Self discharge of Lead Acid Battery is the electrical Ampere Hour (Ah) capacity that is lost when the
battery is not being charged and there is no load connected to it i.e. it sits idle in storage. Self-discharge is caused
by electro-chemical processes within the battery and is equivalent to application of a small electrical load. For
example, Lead Acid battery stored at 30°C / 86°F would self-discharge at around 1% of remaining capacity every
day. Self-discharge increases with increase in temperature. Self-discharge of the battery under long term storage
will create condition equivalent to under charging and consequently, lead to sulfation as explained at Sections
1.4.4.1 above. To prevent this, the battery should be “Float Charged” as explained in Section 1.4.3.3.
1.4.6.2 Float Charging of Batteries under Long Term Storage: In order to prevent sulfation due to under
charging as a result of self-discharge, Lead Acid Battery under long term storage should be rst fully charged and
then left under continuous charge using a suitable “Float Charger” that will Float Charge the battery and provide
low value of “Float Charge Current” of around 0.1% of the Ah capacity of the battery to compensate for self
discharge. Samlex Model SC-05 and SC-10 SunCharger Solar Panels may be used. These are designed to provide
this “Float Charge Current" and thus, prevent sulfation.
1.4.7 Rated Capacity Specied in Ampere-hour (Ah)
Battery capacity “C” is specied in Ampere-hours (Ah). An Ampere is the unit of measurement for electrical current
and is dened as a Coulomb of charge passing through an electrical conductor in one second. The Capacity “C”
in Ah relates to the ability of the battery to provide a constant specied value of discharge current (also called
“C-rate” - see Section 1.4.10) over a specied time in hours before the battery reaches a specied discharged
terminal voltage (Also called “End Point Voltage”) at a specied temperature of the electrolyte. As a benchmark,
the automotive battery industry rates batteries at a discharge current or C-rate of C/20 Amperes corresponding to
20 Hour discharge period. The rated capacity “C” in Ah in this case will be the number of Amperes of current the
SECTION 1.4 | General Information – Battery Related
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