General Knowledge of Batteries

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The Terminology of the Lead-Acid Battery

  • (Electromotive Force) Electromotive Force
    Electromotive force is the power that generates electricity and pushes it through the electric circuit. The battery generates it by charging and discharging (chemical energy ↔ electric energy). Units are marked V for voltage.
  • Voltage
    Voltage is the difference between two electrical energy points in the conductor. It is called an electric potential difference (Voltage/V).
  • Nominal Voltage
    Standard voltage specified on the battery → 2V per Cell
    * The official voltage of car batteries is 12V(2V X 6 Cell)
  • Open Circuit Voltage
    This is the voltage when the battery is not electrically connected to the external circuit. It is a stable, open-circuit state created after an hour or more of charging or discharging.
  • Cut-Off Voltage Of Discharge
    This is the voltage where the battery discharge must be halted. In usual cases, the voltage plummets after a certain degree of battery discharge. If discharged below a certain point, it over-discharges and damage the battery. Therefore, this is a voltage designated to prevent overdischarge. Please note that the standards for cut-off voltage of discharge differ according to product characteristics and usage. Car battery cut-off voltage of discharge is 10.5V(1.75V Per Cell X 6 Cell) but differs according to pole plate type.
  • Capacity
    Capacity refers to the performance of the battery. This is the depleted electricity (discharged electricity X discharged time) when discharging a fully charged battery at a set current to battery cut-off voltage. Units are Ampere Hours (AH). The capacity shows the power of a battery. It is the standard that shows the working capacity of a battery after it is charged.
    • 20 Hour Rate Capacity (20AH)
      It is commonly used for showing battery capacity. It is when a fully charged battery is kept at 25 and continued discharging to battery cut-off voltage(10.5V) at a 20-hour rate current.
      E.g.) When XP80’s 20 hour rate capacity is 20-hour rate current X time = shown as 80AH
      →20 hour rate current : 80AH / 20H = 4A → Time for cut-off voltage: 20 hours
      -5 Hour Rate Capacity (5AH)
      It is commonly used to regulate ignition capacity. It is when a fully charged battery is kept at 25 and continued discharging to battery cut-off voltage(10.5V) at a 5-hour rate current.
      E.g.) XP80’s 5 hour rate capacity : 5-hour rate current X time = shown as 64AH
      → 5 hour rate current : 64AH / 5H = 12.8A→ Time for cut-off voltage: 5 hours
  • (Reserve Capacity : Reserve Capacity: R.C) R.C
    When the generator breaks down during driving, the minimum electricity required for the vehicle to stay in motion (considering night and harsh weather conditions) is assumed to be 25A. The reserve capacity shows the time in minutes when the battery is discharged down to 25A and continues to battery cut-off voltage(10.5V).
    E.g.) XP80 has a reserve capacity of 135 minutes
  • (Cold Cranking Ampere : Cold Cranking Ampere: C.C.A) C.C.A
    When the battery is kept for 16 hours at -18 (by KS specification regulations), discharged at C.C.A., and the voltage after 30 seconds can be kept at over 7.2V.
    E.g.) In the case of XP80, it is 630A
  • CCA
    • - Actual CCA
      The number measured when discharged according to actual regulated current
      Higher in larger pole plates. (Large>JIS, EN L>EN LB>N )
      - CCA Measured by Digital Device
      A theoretical number calculated on a program according to voltage and resistance.
      Same regardless of size (Large=JIS, EN L=EN LB>N )