GFX sealed lead acid batteries is an extensive, economical and memory free power source. In order to maximize battery service life, it is important to select a suitable charger and to charge the battery in an upright position. Overcharge will reduce electrolyte and cause quick damage to battery. The charging method depends on the battery application as follows:

• Cyclic operation
  The range of controlled voltage is 2.4V~2.5V / per cell (6V battery is 7.2V~7.5V, 12V battery is 14.4V~15V), limit initial current is 0.4CA or less. The battery is fully charged as long as the charging voltage reaches 7.5V (6V battery) or 15V (12V battery) and charging current drops to approximately 0.01CA. After that, the charger should either be disconnected or switched to float voltage.
• Float or standby operations
  The range of controlled voltage is 2.25V~2.3V/ per cell (6V battery is 6.75V~6.9V, 12V battery is 13.5V~13.8V). When battery held at above voltage, charger will fit its current level and maintain itself in a fully charged condition.
• Recharge battery during storage
  Refresh battery during long-term storage. The regulation range of controlled voltage and current as same as cyclic operation, also short time charge allowed if it is constant voltage charger.
• Rapid charge
  When the batteries are charged rapidly, a large current is required for supplying energy into the battery in a short time. Therefore the charging cut-off devices are installed to avoid overcharging and damaging the battery.
• Charging voltage relate to temperature
  The charging voltage is recommended to be adjusted to compensate for the battery temperature. That may be done by detecting of ambient temperature near the battery instead of the battery temperature.

  (a) Cycle use
  
  
  
  (b) Trickle use
  
  

• Constant voltage charging (Fig7,8)
  The constant voltage charger is the most suitable and effective method to charge sealed lead acid batteries. Its output voltage is preset to protect batteries without overcharging. This method is sufficient enough for the batteries used in general application.
  
  
     Fig.7 Constant voltage charger circuits

• Charging time
  Time is required to complete each charge that depend on the battery discharging condition, characteristics of charger, or the temperature during charge. The following shows the estimated time to charge the battery for cyclic use.
  Cyclic use
  1) Discharge current more than 0.25CA
  Charging time = Cdis / I + (3 ~ 5) h
  2) Discharge current less than 0.25CA
  Charging time = Cdis / I + (6 ~ 10) h
  *Cdis: Ampere-hour discharge before charge (Ah).
  * I : Initial charging current (A)