This is a PC board I made so I can charge a 48V seal lead acid battery from any 12VDC source. This design is simple and uses an off-the-shelf audio crossover coil. It charges my battery from a 12V source that gets switched on once the sun goes down. In the morning my batteries are ready to go and it didn’t cost me anything. Energy from the sun. However I can use with and 12V source that can provide 2-3 amps of power. There is a special circuit that will stop the SMPS once the battery level low around 11 volts. Next day the sun comes up and charges the 12V battery.