Using a positive voltage regulator IC, it is easy to make a simple voltage controlled charger in solar powered devices. LM 2941 CT is the low drop positive voltage regulator with the capability of 1 Amps current output. Unlike other regulator ICs, LM2941 shows a typical voltage dropout of 500mV to 1 V in all temperature conditions. Another important feature of the IC is that a current reduction circuit is included to reduce the ground pin current when the differential between the input and output voltage exceeds 3 volts. When the input voltage exceeds the maximum rating of the IC due to transients, the IC automatically shutdown to protect both its internal circuit and the load. It also has short circuit and thermal overload protection. IC 2941 is the 5 pin IC with an Adjust pin and On/Off pin in addition to input, output and ground pins. A 12 volt 10 watts Solar panel gives around 20 volts and 1.2 Amps current in bright sunlight. To prevent excess voltage entering into the battery, this voltage adjustable charger can be used.
Adjust VR to get the desired voltage to charge 12 volt Lead Acid or tubular battery. The voltage should be 15 volts for charging the battery.