Fez: I've invested in a p-touch labelmaker such as:
https://www.brother-usa.com/Ptouch/Ptouch_HandHeld/#.VIS3u5H0Fok
I got one that has electrical symbols on it and can do "wire labels". i.e. Flags etc. It has a number of label types. The labels are very durable. Every wall wart gets marked: what it's for. The voltage, the polarity, the current and the size of the plug, e.g. 5.5/2.1 gets marked at the plug end with a wire label. If it's missing on the device itself, it gets added.
I use it for so many things. So, yea, if i replaced something, I might put a label in the case as to what was replaced and when and the original part number etc.
I do the same for battery packs, The purchase month/year and website and the OEM part number and the part number I used.
I do it for labtop batteries too.
When I can, I use a Statler Lumocolor fine marker. You can erase the "permanent" ink with methanol and methanol doesn't harm plastics.
So, a smoke detector battery gets marked when it was replaced last with a Stadler pen.
The last time, I used the labelmaker was yesterday. I bought 3 "German engineered" cobalt step drills (Unibits) in a case and one of the bits won't stay in if inverted. So, after thinking for awhile, I got a 1/4" plumbing tubing to 1/8 NPT adapter and attached it with a plastic thread forming screw. Now, it doesn't fall out. Cobalt can break easily.