simulate this circuit – Schematic created using CircuitLab
This is my battery backup system for a laptop pc running 24/7.
So normally the Load is powered from primary supply and the battery is being charged.When the primary power is lost its sensed by the switching circuit turns on the boost converter.
I don't mind a momentary power loss when the switching happens.
Current design is using a diode (schottky?) to block the power going back so it doesn't trigger the power sense circuit or charge the battery when under battery power.
What i need to know
- Is there a way to make this system work without adding a diode so there wont be a voltage drop from primary power to load (MOSFET?)
- what type of circuit is suitable for the switching circuit?
some points to consider
- I cant change the input voltage or Load
- Boost Converter output voltage is adjustable
Also i would prefer not to use any mechanical switching such as relays.
by adding a MOSFET on the high side of the main power connection
Using MOSFET reverse polarity protection doesn't work as intended because when boost converter is active current is fed back in to the charger