Motorcycle Battery Charger with LM1458
This charger is designed for 12V motorcycle batteries and uses the LM1458 dual operational amplifier to regulate the charging process. The circuit provides a safe and automatic charge for lead-acid batteries.
Power Supply
- Transformer: 80 W, 18V AC secondary
- Rectification and filtering supply a DC voltage suitable for charging a 12V battery.
Circuit Operation
- The LM1458 amplifies and monitors the battery voltage.
- When the battery voltage is below the set threshold, the charger provides full charging current.
- Once the battery reaches the preset voltage, the circuit switches to a low-current float mode to maintain the charge safely.
Key Features
- Automatic charging for 12V motorcycle batteries
- Float charge to maintain battery without overcharging
- LM1458 dual op-amp for voltage monitoring and regulation
- Suitable for lead-acid and gel batteries
- Simple, compact, and reliable design
Construction Notes
- Use a suitable heatsink for any power transistors or regulators handling charging current.
- Ensure correct polarity when connecting the battery to prevent damage.
- Include a fuse on the supply line for safety (typically 3–5A for motorcycles).
- Monitor initial charging to confirm proper voltage adjustment before leaving the charger connected permanently.
