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Solar Battery Charger with TLC339 and BUZ11

This solar battery charger is designed to charge sealed lead-acid batteries using solar panels. It provides automatic charging control and prevents battery discharge back into the solar cells.

Circuit Operation

  • The BUZ11 N-channel MOSFET acts as a switch to connect the solar panel to the battery, preventing reverse current flow when sunlight is absent.
  • The TLC339 voltage comparator monitors the battery voltage and controls the MOSFET, stopping charging when the battery reaches the preset voltage.
  • Charging automatically resumes when the battery voltage drops below the previously set threshold, maintaining proper battery charge without manual intervention.

Key Features

  • Automatic solar charging for sealed lead-acid batteries
  • BUZ11 MOSFET prevents battery discharge to solar panel
  • TLC339 comparator provides precise voltage monitoring
  • Automatic start/stop based on battery voltage thresholds
  • Safe, maintenance-free operation

Construction Notes

  • Ensure the solar panel voltage is slightly higher than the battery voltage for proper charging.
  • Use a heatsink for the BUZ11 MOSFET if charging at higher currents.
  • Keep battery and solar panel wiring short and of adequate thickness to reduce voltage drops.
  • Adjust the TLC339 voltage reference carefully to set proper charge and float thresholds.
  • Optionally, add a small fuse or polyfuse in series with the battery for extra safety.
Solar Battery Charger