Battery Dispenser w/Integrated Voltage Meter

Finally, keeping your batteries and volt meter in the same place cannot be any simpler. This unit employs a very simple, mini, digital, volt meter. Batteries are tested by squeezing the front 3 batteries against the internal contacts by pressing the tray against the back wall. This will force the batteries to make contact with the internal contacts/wires running up to the sensor at which time the unit reports the voltage of the front battery.

The volt meter I used (https://www.amazon.com/dp/B00YALV0NG) only costs $2.50 USD and uses a 3-wire design meaning it needs to draw power from two batteries while testing the 3rd. 2-wire variants are available, but require a nominal voltage of ~3v when testing to also power the unit making it unsuitable for 1.5v batteries.

The current incarnation includes enough capacity for 24+1 AA batteries (typical amount when bought in a small volume) with plans to add extensions for up to 48 batters (typical amount for larger volume buys). I already have plans for producing additional sets for other battery sizes (AAA, C, 18350, 18650, etc).

The model is divided into three parts. The main body holds the batteries; dropping in batteries and watching them whip their way down is a little too much fun. The lid includes registration marks for gluing to the body and a small groove for the battery's button ensuring that batteries cannot be inserted backward and that they don't turn sideways as they move through the body. The tray includes/hides the battery contacts and works as the “button” to test the next battery to be removed.

What's wrong with this first draft? I didn't have enough time to print and test more than one iteration. Tolerances are too tight, I had to do some creative sanding on the LCD unit to get it the provided recess. The metal contacts inside the tray and unit are too sketchy to call this a finished product. The registration marks are too small to function properly. The width of the body is about 1mm too wide allowing you to insert batteries backward. I want to move the registration marks and battery button groove out of the lid and into the body. The tray is ½ of a battery's diameter too wide. And I didn't have time to glue the lid on.