I just soldered some wires to my 1.5v motors and stuck them into a breadboard being powered by four double A batteries, but they aren't working. I did a pretty sloppy job soldering them, but when I checked the connections using my multimeter, it clearly said they were receiving 3.25 volts. Any ideas why this could be happening?
Still could be bad solder joints, bad batterys (four good batterys should produce ~6v total when in series), bad wiring, etc..
Have you measured the resistance between the motor terminals when unpowered?
Dead motors ? You say you are providing power from 4 x AA batteries (6 volts) yet you say the motor terminals reads 3.25 volts. This suggests you motor shaft is seized causing the motor to draw excessive current and overloading the batteries. Even if you had dry solder joints, the motors should still run IF they have >1.5 volts on them
You could measure the current (only if your multimeter has an amps range - milliamps is not enough). A stalled motor may draw a fair bit of current, 0.3 to 2A perhaps? Normal values perhaps 0.1A.
Putting 6V onto a 1.5V motor will rapidly burn out the commutator in my experience.