12v battery charger using TIP3055
A very simple 12v battery charger circuit can be designed using a TIP3055 power transistor to limit the current to the battery by turning off when the battery voltage reaches approx 14v or if the current rises above 2 amp.
This battery charger electronic circuit is very simple and require few external electronic parts . Signal to turn off the TIP3055 transistor comes from two other transistors , the BC557 and BC 547. Firstly, the circuit turns on fully via the BD139 and TIP3055. The BC557 and BC 547 do not come into operation at the moment.
As the battery voltage rises, the voltage divider made up of the 1k8 and 39k creates a 0.65v between base and emitter of the BC557 and it starts to turn on at approx 14v.
The input voltage required by this charger electronic circuit project must be around 15 volts DC.