I have a project (doorlock) with MCU / LCD / Keypad and solenoid (lock) connected together. MCU, LCD and Keypad runs at 5V while solenoid runs at 9V.
I'd like to provide the power with a battery, so I was initially thinking about getting a 9V battery to provide power to the solenoid, and use a LM7805 regulator to provide 5V to MCU, LCD and Keypad. Problem is, on idle, the 5V components draw about 100-130mA of current and the solenoid will draw about 500mA on activation (for about 5 seconds), so that's 630mA of current being drawn. I imagine the battery will get either extremely hot or limit the current.
What's a good strategy of providing a consistent 9V/5V voltage with a high current while minimizing the battery size? Something like a car battery may work here but they are way too large to fit in the box.
Edit: The components are normally powered by AC/DC wall adapter. I'm trying to make a battery backup system pretty similar to shown here (http://www.electroschematics.com/6279/battery-backup-circuit/), so that the doorlock is kept in operation if the AC power dies out for whatever reason.