An Engineering exploration to make Apple’s mouse charge wirelessly
A few weeks back, the popular youtube channel, Unnecessary Inventions created a video detailing their attempt to fix a well documented design aspect of Apple’s Magic Mouse®.
The mouse features a built-in chargeable battery with a lightning port — that interestingly resides under the mouse. Fans and critics of the mouse have speculated on the many potential reasons for this design, which ultimately prevent charging while in use.
Unnecessary Inventions set out to “fix” this issue by 3d printing a riser / side-car of sorts, that would prop the mouse up just high enough to allow for a low-profile lightning charger to be plugged in. After completing the project however, they discovered there is some type of hw or sw control mechanism that prevents the use of the mouse while it is charging.
Unfortunately, I could have helped save them some time and told them that.
Years ago I shelved a similar side project, with the goal of never having a dead mouse at the start of a work day. I also found that the mouse is not usable while charging and then subsequently paused taking this any further but not without a valiant half-step attempt.
My solution was to retrofit the mouse with a wireless inductance charger that would sit on a wireless charging mouse pad.
In practice this sounds easy enough — 3d print some parts, buy some others and good to go?
Not exactly. I quickly found that without the perfect tolerances on my 3d printed bumpers, the optical sensor of the mouse could not track as smoothly as Apple had designed it. After a few iterations and some work to find the right third-party parts, I had a basic working prototype comprised of:
- One Wireless Inductance charger
- One Wireless Charging Mousepad
- Two 3D printed replacement bumpers to house the wireless charger
Fortunately, there are wireless inductance chargers with lighting connections on the market. I also found a wireless charging pad that would suffice for my testing.
Below was my “solution”.
The bulk of my time to get this to work was to iterate on the tolerances of my 3d printed bumpers until the optical sensor worked as smooth as before the retrofit.
The bumpers need a bit more rounding, and post-polish sanding. If I were to do this over, I would change the design ever so slightly, and try different materials such as nylon.
While I achieved the usability I was looking for, I needed to frequently remind myself to place the mouse on the chargeable area. It’s at best a micro-optimization, which is something I tend to avoid in the development of software. Rough tests show that charging takes place at about 1% every two minutes. True to the findings of Unnecessary Inventions, when the mouse is charging the cursor cannot move. It is good to know that the presence of a lightning connector plugged in is not the control mechanism that disables the usability.
Ultimately, I decided to put the stock bumpers back on, charge when needed, (given that the battery takes a really long time to deplete) and get back to writing code.
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