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.
Those batteries in your photo are NiMH batteries… which discharge on their own at a fairly rapid rate even if you’re not using them at all. They’re also pretty big and heavy for the amount of power they provide (which, due to the self-discharge issue, is effectively a lot lower than the official number on the battery).
I strongly recommend investing in devices that use 18650 batteries. They’re about the same size/weight as a AA, and they last much longer (both in terms of from full to flat and also the number of years (decades?) of use you’ll get from the battery.
A lot of “proprietary” batteries are in fact a bunch of 18650 cells wired together.
It’s worth investing in good ones - the quality varies significantly from brand to the next. With a good 18650 cell, you won’t be replacing it when the battery expires, you’ll be transferring it to a new gadget when the gadget is broken or so old that you decided to buy a new/better model.
They make USB rechargeable lithium ion batteries in every common form factor. I use lithium rechargeable AAA batteries in my mouse and they work great. You don’t even need a charger, they are USB-C. Highly recommend.
They can be very useful for the devices that want the full 1.5V, as they can provide that 1.5V across their whole charge cycle, unlike NiMH and Alkalines that drop down the voltage. They are also lighter than NiMH. However they are also more expensive and for most devices NiMH will work just as well, while costing less.
Another thing worth mentioning, NiMH show charge in mAh on the package, Li-Ion very often give it at mWh, which makes the Li-Ion look 20% bigger than they are.
I mean I can’t really blame them for being smaller, the USB port is a lot of value added but is also pretty huge.
Low self discharge NiMH batteries have been available for a long time now. They hold a charge for several years.
An 18650 is way bigger than a AA
But got damn does it ever put out some insane light! My flashlights turn night into day.
While all this is true, unfortunately not many devices support swappable 18650s, either they have swappable AA/AAA or have built-in 18650s that would require disassembly to replace. However, if you CAN find a device with swappable 18650s (the only ones I’ve found so far are flashlights) they’re absolutely great!
The main barrier is when you need multiple batteries.
If you install a dozen 18650’s in a device (or thousands in a car), they will work great as long as they’re all at the same charge level and can maintain the same voltage throughout the discharge cycle. If they can’t do that, then the battery could catch fire. Yikes. So any device with multiple 18650 cells will hard wire them together so the user is forced to use and charge and discard the entire set of cells as a single battery.
AA/AAA NiMH batteries won’t catch fire if they’re uneven, but being uneven will damage the batteries. You don’t need to keep them together to be safe, but you do need to keep them together if you want the batteries to last longer than six months. Keeping them together can be a logistical nightmare and it’s the main reason I’ve stopped using them… it’s just too much work to keep all the batteries together (especially if the device is shared in a household or workplace). If you get it wrong, then they don’t last much longer than disposables.
Disposable batteries have the same issue - but since they’re disposable you’re probably pulling four brand new batteries from a packet.
An 19650 cell holds about the same amount of energy as five AA batteries. So there are a lot of devices that can run well off a single battery, and those tend to be the ones that are user replaceable.
I am not aware of many devices that use swappable 18650’s either. Off the top of my head the only ones i’m aware of are vape devices.
My OWON portable oscilloscope does. The only device I know of.
There are also flashlights with 18650s. There are some powerbanks with exchangeable 18650s as well.
But that’s all I know of.
These powerbanks can set your house on fire if the chip shorts out: the wire gets very hot and melts through the plastic like this: Odysee/YT/Piped. I recommend installing a 2A (for 1A powerbanks) or 5A (for 2.1A powerbanks) automobile fuse in series with the cells or each cell individually.
I have a set of lasers powered by them as well. Love that it makes the whole thing a bit larger and durable.
Wait, do they not make AA-sized 18650 batteries?
But 18650 size is manufactured at much higher scales than other sizes, and therefore it’s the cheapest, and therefore it continues to dominate.
They do, they are called “14500” (the name is the dimensions of the battery). Though it is important to remember that, despite looking exactly the same as a regular AA, they are 3.7V, so they’ll kill your regular 1.5V electronics if you put them in there. Not sure what they are actually used in, flashlights I assume, but they seem quite rare overall.
Only place I have seen them commonly used is solar powered garden lights, though in that case they are LiFePO4 3.2V, not Li-Ion 3.7V.
Besides being the wrong size by definition, AA batteries are expected to have 0.8V to 1.5V, while Lithium Ion cells (such as 18650) have a voltage range of 2V to 4.2V. That’s completely incompatible, you couldn’t even replace two AA batteries with a single Li-Ion cell.
Couldn’t it theoretically be fixed with a voltage regulator?
Don’t they need a circuit protection to not over-discharge lithium batteries? Most AA devices would suck all the juice from the battery until it stops working.
18650 isn’t a specific type of battery, but a size. 18mm diameter, 65mm length, and 0 typically represents it being cylindrical in shape. 18+65+0
Heres a quick read