Using an LM317 voltage regulator can be made very simple charger, very useful for charging lead acid batteries. Unlike NiCd batteries, they must be recharged by connecting to a constant voltage (proper size). In this case, load current will provide a good indication of the state of charge.
This charger is composed of IC1 voltage regulator, and a variable current limiter consisting of T1, R1 and R4. Once the current through R1 is too large, T1 opens and the output voltage decreases. The output voltage (in volts) is given by: 1.2 (P1 + R2 + R3) / R3
Current limiter is operating under a current of 0.6 / R1 [amp].
To recharge the batteries of 12 V, the value required for P1 + R2 should be about
Input voltage must be at least 3 V higher than the output.
LM317 integrative heat radiator needs, not only because it can be easily destroyed, but also because, at high temperatures, it can provide maximum output current