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CHARGING METHODS - CONTINUED

  • a)

    Temperature compensation of charge voltage Charge voltage should be compensated to the ambient temperature near the battery, as shown by the figure below. Main reasons for the temperature compensation of charge voltage are to prevent the thermal runaway of the battery when it is used in high temperature conditions and to secure sufficient charging of the battery when it is used in low temperature conditions. Prolongation of service life of the battery by the above- described temperature compensation is expected as follows

    • At 30C: prolonged by approx. 5 %

    • At 35C: prolonged by approx. 10 %

    • At 40C: prolonged by approx. 15 % In low temperature zones below 20C, no substantial prolongation of the battery life can be expected by the temperature compensation of charge voltage.

Compensated voltage value

2.7

2.6

  • c)

    Charging temperature

    • (1)

      Charge the battery at an ambient temperature in the range from 0C to 40C.

    • (2)

      Optimum temperature range for charging is 5C to 35C.

    • (3)

      Charging at 0C or below and 40C or higher is not recommended: at low temperatures, the battery may not be charged adequately; at high temperatures, the battery may become deformed.

    • (4)

      For temperature compensation values, see a).

  • d)

    Reverse charging

Never charge the battery in reverse, as it may cause leakage, heating or bursting of the battery.

e) Overcharging Overcharge is an additional charge after the battery is fully charged. Continued overcharging shortens the battery life. Select a charge method which is specified or approved for each application.

Charge voltage / cell

2.5

2.4

2.3

Cycle use

Minimum voltage

Trickle use

Maximum voltage

Maximum voltage

f)

Charging before use Recharge the battery before use to compensate for capacity loss due to self-discharge during storage. (See "Refresh charge" (auxiliary charge) table on page23.)

2.2

Minimum voltage

  • -

    20

  • -

    10

0

10

20

30

40

50

Temperature

˚C

b) Charging time Time required to complete charging depends on factors such as depth of discharge of the battery, characteristics of the charger and ambient temperature. For cycle charge, charging time can be estimated as follows: (1) when charge current is 0.25 CA or greater: Tch = Cdis / I + (3 to 5) (2) when charge current is below 0.25 CA: Tch = Cdis / I + (6 to 10) ,where Tch : Charging time required (hours) Cdis : Amount of discharge before this charging (Ah) I : Initial charge current (A) Time required for trickle charge ranges from 24 to 48 hours.

Sealed Lead-Acid Handbook, Page 24

January 2000

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