LEAD ACID BATTERY CHARGER

• Here is a lead acid battery charger circuit using IC LM 317.The IC here provides the correct charging voltage for the battery.
• A battery must be charged with 1/10 its Ah value.This charging circuit is designed based on this fact.
• The charging current for the battery is controlled by Q1 ,R1,R4 and R5.
• Potentiometer R5 can be used to set the charging current.As the battery gets charged the the current through R1 increases .
• This changes the conduction of Q1.Since collector of Q1 is connected to adjust pin of IC LM 317 the voltage at the output of of LM 317 increases.
• When battery is fully charged charger circuit reduces the charging current and this mode is called trickle charging mode.

  
  
  

  NOTES:
  

  • Connect a battery to the circuit in series with a ammeter.Now adjust R5 to get the required charging current. Charging current = (1/10)*Ah value of battery.
  • Input to the IC must be minimum 15V to get 12 V for charging the battery .Take a look at the data sheet of LM 317 for better understanding.
  • Fix LM317 with a heat sink.