This page contains data on the capacity of various aftermarket batteries for portable MiniDisc units.
This data is derived from user testing on small samples, and will not be 100% accurate! Battery capacity can vary from batch to batch, so your battery might not deliver the same numbers as found here!
If you have multiple batteries from the same brand, mark them in some way and write down the capacity for each battery, don't mix them. I've observed batteries from the same brand with a 50mAh difference in capacity.
The testing done by u/rcboosted and u/Snoo-34188 was done using an OPUS BT-C3100 battery-charger/tester.
If the battery is new, the capacity should increase with each cycle. Keep running the refresh-program until the discharged capacity remains more or less unchanged. My batteries were used enough to have been “exercised” to full capacity, so the measured discharge was within ~5mAh between cycles. Now we're ready to do the final test:
For increased accuracy, making 2-3 measurements of each battery and averaging for each battery should yield the best results.
You don't need an OPUS BT-C3100 to contribute, but it helps. Any other testing-unit you have that can do the same job is welcome. Please write a how-to for that unit as well. For the numbers, new measured capacity would be:
((Current measured capacity * Batteries tested) + your results) / New number of batteries tested = New measured capacity.
…and remember to update the number of batteries tested!
Example: