3 X AA Switched Battery Box

This is a remix of...

Parametric Spring Contacts Battery Box for AA Cells

https://www.thingiverse.com/thing:1755397

by ffleurey, posted September 05, 2016

I really like the original design. The purchased spring contacts are fairly cheap in quantity, easy to use and fit perfectly into the OP's model. They are a great way to make a professional and functional battery holder. The wiring channels in the back make everything compact and easy to wire.

I've modified the 3 X AA file adding a switch, a cover and an optional rear cover.

I hope to do this for the 4-cell 6 Volt version as well and will post the files separately if and when, but will add a link here to the new post.

[EDIT - 5/20/23] - The 4-cell version is now posted here...

https://www.thingiverse.com/thing:6036477

I flipped the center battery around, providing a more conventional "nose to tail" layout of the batteries. This also shortens the internal jumper paths and eliminates a couple of crossovers where the jumpers would have to cross the center wire channel in the original layout. Electrically, it's still the same - three cells in series providing a nominal 4.5 Volts.

The original external mounting lugs are eliminated. Instead there are a pair of countersunk holes sized for M2.5 flat head screws in the bottom of a couple of the battery trays. They don't interfere with the cells.

The top cover is secured with an M3 X 16 mm Allen head cap screw engaging an M3 X 5 mm threaded brass insert pressed into the case from the bottom. The pocket in the cover where the screw head fits is sized to accept an M3 flat washer under the screw head. There's a little clearance (~ 0.5 mm) between the screw posts in cover and case so a small paper or acetate disk can be used as a screw retainer to keep the screw captive in the cover.

Unfortunately, the switch is in the negative lead but didn't seem to be worth the effort of changing.

The bottom/back/rear cover is optional. When assembled, the contacts and solder joints protrude slightly from the rear of the box. The back cover is intended to be glued in place after the wiring is done. It provides a flat back surface and protects against accidental shorting of the connections, at the cost of adding about 1.5 mm to the overall height of the box. If used, there are holes for the mounting screws to pass through the back cover.

The box and top cover files include semi-circular hold-down tabs 0.2 mm high to help prevent the corners lifting from the bed while printing. Those are easily removed after printing with a hobby knife.

All external corners and edges are radiused.

Switch: https://a.co/d/3sVIYnA

Switch Screws: M2.5 X 6 mm flat head wood screw (holes in switch posts are sized for these)

Battery Contacts: https://a.co/d/8JTwsrs

Threaded Insert: https://a.co/d/fiNKmpN

Printed in PLA without supports; 1 mm shell; 12% infill; 0.3 mm nozzle; 0.2 mm first layer; 0.15 mm layer height

I originally put heat shrink on the switch solder joints but the solder lugs and wires at the switch are so stiff after soldering that I don't believe accidental contact there is likely; in the second prototype, I eliminated the heat shrink.

If desired, the wires can be secured in the channels at the bends and where exiting the case with UV cure glue or cyanoacrylate.

Use 26 gauge solid wire for the intercell jumpers (white in images); 26 gauge stranded for the output and switch wire (red and black in images).