This article explores how an Wall Adapter to Battery Changeover Circuit works, how it is designed and how it is built using the LTC4412 integrated circuit.
How can I use a line-powered switching power supply instead of a battery?
simulate this circuit – Schematic created using CircuitLab If you always want to use the line-powered switching power supply in preference to the solar-charged battery, then arrange that power supply to put out a little higher voltage than the battery. It doesn't need to be much, even just a few 100 mV would do it.
In this switching circuit, the source of power supply to a load circuit is changed between the battery and DC power. The main components that play important roles in the functioning of this circuit are the relay, switching transistors, and zener diode. In this circuit,three relays are used.
What is the power output of the automatic switching circuit?
The final power output of this automatic switching circuits will be used to power 12v devices (30 Ampere maximum). It is important that the circuit provides uninterruptible power during switching and that it works in 11-14v range. P.S.: please provide a detailed list of the scheme and electrical components to be used. @Arsenal Why not?
Can a portable equipment operate from a battery pack or external power source?
Portable equipment that can operate from a battery pack or an external power source (such as a wall-adapter or external supply) needs to be able to smoothly switch between the two power sources. This application note describes a circuit (Figure 1) that switches power sources with good efficiency and without switching noise. Figure 1.
Take a look at the PowerPath Controller LTC4412 or the Prioritized PowerPath Controller LTC4417 from Linear Technology. They have some more of these PowerPath devices. Or you can take a relay. The wall adapter controls the relay to open/close the line to the battery. AC wall adapter plugged in, relay on and battery line disconnected, vice versa.
When the adapter is plugged in, V1 will be 11 volts (ish). When the adapter is removed, your circuit will have 8 volts at V1 from the battery. There is no risk of the battery being charged by the adapter as the battery diode will block all current in the reverse direction. The diode part numbers are not critical.