Dummy AA battery

thingiverse

A dummy AA-battery lets you short out one position in a battery pack so that you can get a different voltage. For example, if you have a four-cell pack and want to power a circuit with 4.5 volts rather than 6 volts, you can replace one of the cells with a dummy battery. Another use is to connect a power-supply into a battery pack with one of these. Just ensure you get your polarities right, and you probably need a few dummies for the other position(s) in your pack. Don't use an external power-supply AND a real battery together - that's a bad idea. I wasn't the first one to think of this, but I found a couple of other designs on Thingiverse for it as well, and they were all missing some nuance that I wanted in my design. And given that it's just a cylinder, it's a pretty quick thing to throw together. I made my first pass a bit better, and it works so well that I decided to share it here. You simply string a wire through it, loop through the holes like sewing a button, and you get a good contact in most battery holders. I looped through the positive (bump) end 3-times with 22-gauge wire and a 'Z' pattern on the negative (flat) end - that works for me. Need a AAA battery? You can probably scale it if you wish. Print Settings: Printer: MP Select Mini Rafts: Yes Supports: No Resolution: 0.1mm Notes: This should print well with .2mm resolution as well, if that's what your kit does. I made an arched interior so it will print without supports just fine. I used a raft with 4mm extra size to ensure I got good adhesion. Post-Printing: Wiring it up. You can use any old wire laying around - I just stripped the ends, but really insulation on the inside bits doesn't really add any value. Don't go with too small of a gauge - remember you can get a fair bit of current out of a AA battery and you don't want it to go 'open' on you. Oh here's a thought: you could use super-fine wire and it could be a fuse? A pair of tweezers or fine needle-nose pliers are useful for helping you with the threading.