I know these are currently out of fashion but I'm still thankful they exist.
Let's remind ourselves of devices that use(d) these standardized batteries:
- Toys
- Digital cameras
- Torches
- Gadgets like fans
- Wireless keyboards
- TV remotes
Thanks to having a standardized system of batteries,
- You can use the same battery across several devices. This is a no brainer but it's very practical.
- Batteries can charge quicker thanks to being put in a dedicated charger and not being limited by USB cables. (But yes I concede that USB has been updated for faster charging over the years)
- Devices don't have down time when their battery is charging. To charge, the battery is removed from the device and can immediately be replaced with a fresh one.
- You'll never have to trash a device due to an expired battery. Just buy a replacement. And building on this...
- Any improvements in future battery technology can be retro-fitted into your existing devices. And there is a high incentive for future improvement, because...
- An accessible (due to easy replacement) and large (due to many devices) battery market is very attractive to competition.
If you look at the pros I listed, they all happen to be things that would be very useful for electric cars. So I think it would aid the adoption of electric cars if their batteries were standardized too.
Alkalines leak a lot and they seem to be worse these days than they used to. From personal experience, there is about 1:10 chance you'll be scrubbing battery contacts after using Alkaline. And if you forget to remove the battery when the device goes into storage, there is about a 100% chance it will be a crusty mess once you look at the device again, it can take years, but it's pretty much unavoidable.
NiMH don't leak, or at least much less frequently with much less catastrophic results. Also with modern low-self-discharge ones (Eneloop, Ikea LADDA) they last years, so they are very usable in TV remotes and the like.
There are a couple of rare devices that really want 1.5V to function properly (e.g. WMR Controller), in those cases 1.5V LiPo batteries can make a good rechargable alternative, but they are substantially more expensive than plain NiMH.