Comment by dragontamer
8 hours ago
That's not the reason.
Alkaline batteries only have 1.5V for a short time. In practice, toys are designed to opeerate off of 1V to 1.5V, because Alkalines vary _wildly_ in voltage during use.
NiMH at 1.2V _STAYS_ at 1.2V, even when drawing 1Amp or more (under these conditions, Alkaline would have long dropped below 1V).
EDIT: This is also a problem because "nicer toys" will measure the voltage assuming an Alkaline is "full" at 1.5V and dies at 1.0V. However, NiMH starts at 1.35V, then "plateau" at 1.2V, and stays there for most of its life, before rapidly falling off to 1.0V or .8V like a cliff at the end of its life. So NiMH life "cannot be predicted" by any simple metric.
I had an issue with the original Apple Magic Mouse that would not work correctly with NiMH batteries but work fine with disposable AA. The mouse would be fine for a few days then randomly stop working; using fresh NiMH would revive it again. I assumed it was due to 1.2v vs 1.5v but perhaps that particular mouse (or all Magic Mice) was just bad.
I have an acurite 5in1 weather station running on eneloops/laddas. It whines about the batteries being low but runs for about a month in any conditions. I just rotate and recharge them at the start of the month.
Looking at the discharge curve for an alkaline, much of the energy is below 1.2V even under light load. A device that works with alkaline and not NiMH due to voltage is broken as designed.
https://lygte-info.dk/review/batteries2012/Duracell%20Ultra%...
If you need 1.5V / 3V for some reason, you could maybe insert a tiny boost converter from AliExpress (1€, less than 1 cm in all dimensions). I have done that for a string of fairy lights.