So, are your batteries always draining so fast in your air-mattress pump? Well, there's an easy fix.
Step 1: Items Needed
1: Battery powered air mattress pump
2: Wall wart
3: Soldering iron
5: Hobby knife
The pump I used runs on four D cells. That's six volts, and I had just gotten a wall wart from an old cell phone that had an output of 4.9 volts. Since the voltage of the batteries the pump was running on had dropped below that voltage and the pump was still working, I decided the wall wart I had was good enough.
Step 2: Connecting the Wall Wart
This is really simple.
By looking into the battery compartment, you can see the battery terminals. Just follow the ones leading to the motor to determine the + and - of the motor.
Then, cut off whatever connector is at the other end of the wall wart, leaving as much wire on the wall wart as possible, and then strip the wires. Mine were colored black and red, so that was easy, but otherwise you can test the wires with a multimeter. Then, just solder the wires onto the motor + to + and - to -.
I was able to just run the wire out in the crack between the pump and the lid of the battery compartment, but depending on the type of pump you have, you may need to make a small notch for the wire.
Step 3: Finish
It is that easy! Just plug it in and it will* start.
*A little note though -- the output of my wall wart was only 450mA, and that doesn't run the motor on its own, so I still need to put batteries in it, but adding the wall wart does boost the performance. If you used a wall wart with a higher amp output, it would probably run the pump on its own. I might change my own if I find a better wall wart.