This Over-Engineered Battery Charger Automatically Loads Up Dead NiMH AAs
If you still use NiMH rechargeable AA batteries, then you absolutely must check out Max.K’s automatic battery charger called SPINC.
Most of the world’s consumer electronics manufacturers followed the blueprint set by Apple and now put internal rechargeable lithium batteries in their devices. But there is a still a market for good ol’ fashioned rechargeable NiMH AA batteries. Whether for vintage electronics or modern devices that don’t have a cost justification for internal batteries, rechargeable AA batteries can come in handy. But keeping them charged up and ready to go is a big inconvenience, which is why Max.K built this completely over-engineered automatic battery charger for NiMH AA batteries.
Max.K designed this device, called SPINC, to be as effortless as possible for the user to operate. Just drop a handful of batteries into the hopper at the top (orientation doesn’t matter) and it will take care of the rest. It will grab a battery, push it down between the charging contacts, detect the polarity, and start the charging process. Once the battery is full, the device drops the battery into a chute with its friends, where the user can grab fresh batteries whenever they need them. There is even a nice display on the front for status information and it also shows the date and time, so the device can double as a desk clock.
Aside from the very useful polarity-correction circuit, SPINC uses pretty conventional charging hardware. It can fast-charge NiMH AA batteries at up to 1A and Max.K created a custom PCB to keep everything tidy. The stand-out features are the lovely design, the motorized feeding mechanism, and the display.
There is no substitute for good design and Max.K did a fantastic job with SPINC. The enclosure and mechanical components were 3D-printed, but the device still has a premium appearance. Inside the enclosure is a servo-actuated, 3D-printed mechanism that grabs batteries from the hopper and holds them between the contacts. After charging finishes, that same mechanism drops the batteries down the chute. The display is a 2.7” 400×240 LCD from Sharp with a touchscreen, so users can set the time and change settings. A Raspberry Pi RP2040 microcontroller handles that and controlling the servo motor.
If you’re interested in making your own SPINC device, Max.K uploaded all of the necessary files to GitHub. You will need to order the custom PCB and that requires a lot of small SMD components, but the results seem to be worth it.
