batt chrger with ptc as curent limiter
Find something usefull:
a)
This high-performance charger quickly charges lead-acid batteries, and turns off at full charge. At first, the charge current is held at 2 A, but as battery voltage rises, current decreases. When current falls to 150 mA, the charger automatically switches to a lower float voltage to keep from overcharging. When you hit full charge, transistor Ql lights the LED to indicate that status.
b)
Adjust by setting the 500 ohm resistor while attached to a fully charged battery.
c)
An LM317HV regulator is used as a current-limited charger. If current through R4 exceeds 0.6, Ql is biased on, which pulls the ADJ terminal of the LM317 HV to ground and reduces the battery- charging current. This one is for 6V, but you can adjust resistors for 12V.