The batteries for all of these units are 10+ years old and generally even a new one (if you can find it) is "new old" stock, so folks have been experimenting with 3D printing an enclosure for a 3.7V 350mAh battery as a substitute: https://www.hallaminventions.com/projec ... -obsession or https://www.head-fi.org/threads/diy-lip ... ld.960086/
It looks like a pretty easy build (literally just soldering contacts onto trimmed wires, then gluing the contacts into place), and Adafruit sells a similar battery that I think may fit: https://www.adafruit.com/product/2750 (But, it looks like it's maybe ~1mm thicker?)
Would appreciate advice here, as I could order the battery and try if this all seems fine, but a few questions:
- Is the Adafruit battery mentioned here essentially (potentially?) to the same spec as the eBay equivalent of the build's battery and likely approximately the same physical dimensions, and is the aforementioned larger dimension on the Adafruit page potentially more of a "worst case" in this instance? Its auction lists a ~40mm height, and fit really does matter here since it's a small device. I may not know the answer to this without actually measuring the batteries themselves, though.
- The main thing I'm concerned about is charging compatibility ... luckily the original batteries for this MD player (which are charged by the player themselves) were indeed Lithium-Ion. This substitute battery has a protection circuit, so is this likely totally OK for use and charging? (Some other players of this generation used NiMH batteries, but luckily this was not one of those.)
Thanks for any thoughts!