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.
An 18650 is way bigger than a AA
Low self discharge NiMH batteries have been available for a long time now. They hold a charge for several years.
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!
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.
There are also flashlights with 18650s. There are some powerbanks with exchangeable 18650s as well.
But that’s all I know of.
Wait, do they not make AA-sized 18650 batteries?
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
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.
That can actually work. A single 14500 Li-Ion along with a dummy battery can work in many devices, as they have regulators for the voltage in the device (it might blow up other devices and won’t give any energy advantages). That said, there is very rarely any use for this these days, as you can buy 1.5V AA Li-Ion batteries with the voltage regulator build in, that will work in all devices. More expensive than NiMH however, so only really good when the device absolutely needs the 1.5V and isn’t happy with the 1.2V of NiMH.
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.
The problem with those is that the device loses the ability to sense the charge status of the battery, since the voltage remains the same until it’s empty.
Yes.
The other problem with lithium batteries like 18650s is that they need to be handled with care so manufacturers don’t want users swapping them in and out like AA/AAA. This is why they build them into devices and have you charge them through a regulated port.
Also there are numerous different versions and sizes of 18650, some come with protection circuit, some don’t, some have flat top, some have button top, and whatever type you end up with might or might not fit your device. Makes the whole situation quite confusing for the average user.
Well there aren’t really different sizes of 18650s, if you chance the size it’s no longer an 18650.
The flat vs button top issue can be annoying though
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.
18650s are in no way close to the same size as AA batteries. Your other points ring true and I generally agree with them though.
For example, basically all power tool batteries.
If they advertise ~12V, it usually means it is 3 ‘cells’ of 18650s in series. Crack open the case on such a tool battery and you’ll find just that – 3 18650 batteries for a little one. A high capacity battery might instead of 6, with 3 pairs of 2 parallel batteries, doubling the capacity. And nothing but weight and size stops them from just making them ever-larger.
18-20v tools are 6 cells (18v is the nominal voltage, 20v is the ‘max’ voltage at full charge). For higher cap, add more batteries in parallel in each series cell.
It is RARE to be able to service these unless you have some specialized skills. Typically, they are spot welded together, which can be dangerous to attempt to DIY. That said, often when a battery ‘fails’, it’s actually just one 18650 that has failed and taken the others down with it.
These days you do see other sizes. 21700s or even pouch batteries are starting to be more common when tools need more stored joules per unit volume.
There are some clever innovations from some tool manufacturers too.
DeWalt has launched batteries that work with both 18v and 54v systems, by having different pins on the output wired to different points in the battery chain.
(3 sets of 3 in series for 18v, or 9 in parallel for 54v, I’m assuming)
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.
It infuriates me that we use Wh instead of Joules for this.
It’s like measuring distances with time – “NYC is 3.4 highway hours from DC” – except doing it in a world where no one has any idea what speed people drive on the highway.
@abhibeckert I have those from Eneloop. They do not discharge that fast as the old generation of rechargeable batteries. Yes they do, but the rate is quiet slow.
Same. People used low quality Ni-Mh batteries and got what they paid for. Eneloops have worked great for me. Believe it or not, Duracell has been great too. It’s the energizers that have all been awful for me.
I second that. Have been migrating devices over to eneloop batteries successfully. (other NiMH batteries go flat after a month even if not used.)