In this instructable we will be getting a free thermistor from a dead rechargeable lithium battery. In this instructable I will be using a old iPod nano 1st gen battery. Any rechargeable lithium battery with three leads should work.
PLEASE NOT WE WILL BE TAKING APART A BATTERY. THIS COULD BE DANGEROUS. PLEASE USE APPROPRIATE SAFETY GEAR AND BE CAREFUL. AND I AM NOT RESPONSIBLE IF YOU MANGE TO DAMAGE SOMETHING WITH THIS.
Step 1: Take a Apart the Battery
What we want is small pcb where the wires go in. Mine was taped on with kapon tape and wrapped in masking tape. It was attached to the battery with two tabs that wire-cutters made short work of. You could de-solder these as well, but we will not be using these connections so there is no point. Take the pcb and dispose of the lipo cell according to local regulation (these are usually considered hazardous waste and should be taken to a battery drop off).
Step 2: The PCB
I used a multi meter to check that the thermistor is connected between black (gnd) and the white (themistor out) wire (all the batteries I have seen use the color codes) . Anyway make sure the is a impedance between the black and white wires. Mine was 10k at room temp. The red wire can be cut off as we wont need it anymore. That's about it there is your thermistor.
Step 3: Arduino Interface
Finally I hooked it up to an arduino with a 10k resistor as shown in the picture. It worked great. At some point I might figure out exactly how much the resistance changes per degree Celsius increase. If do I will add it. I hope you enjoyed my instructable.