Technology

Lithium-ion batteries are being used in lots of modest gadgets in which they don’t belong, such as flashlights and TV remotes. There is a class of gadgets that you should never have to charge—ones that tend to be needed right away, at specific moments. A flashlight, for example, serves its most essential purpose during a blackout, when juicing up its battery would be impossible. Yet some flashlights are now designed with batteries that cannot simply be swapped out—as if having lithium-ion cells somehow made them better instead of worse.

The guys at [email protected] really like flashlights with removable lithium-ion 18650 cells.

goes looking

https://en.wikipedia.org/wiki/Self-discharge

That has 2–3% per month self-discharge rate for lithium-ion.

It has low-self-discharge NiMH batteries -- Eneloop is a popular example -- as having the lowest self-discharge rate of the rechargeable types, at 0.25% per month. That's higher than alkaline, but for a lot of things, that's fine (and alkaline does have self-discharge too).

Recently, I had to go into my attic to investigate a roof leak. It’s dark up there, so I pulled out a nifty headlamp that I’d purchased on a lark a while back, on the premise that sometimes you need a headlamp. That time had come! But then I realized that my headlamp needed to be charged, which meant digging up the right cable and AC adapter, and waiting hours until its battery was full. All that waiting turned out to be in vain, because the recharged light went out minutes into my task, just when I had reached the deepest darkness of my attic. Somehow, I got out again.

I have a headlamp that takes AA batteries, a battery charger, and a bunch of NiMH Eneloops. They don't have the energy density of lithium-ion batteries, but I can do what the author wants with it, charge and let them sit for a reasonably long period of time, and still have them pretty usable.

But I generally don't even bother these days, because I also have a cell phone always with me with a rechargeable lithium ion battery that gets charged every day and has a built-in flashlight, and is good enough for most small flashlight stuff. I have a couple of flashlights floating around (as well as one of those fancy 18650-lithium-ion ones with fancy firmware and all kinds of crazy stuff that the [email protected] crowd likes), but I just don't use them any more, because the cell phone is good enough for most stuff, and it's always with me. And the cell phone can charge extremely quickly relative to its discharge rate and has a decent battery.

And for most of these devices, they can charge and be used at the same time. That is, part of what makes them viable is that they're USB-charged, not that they have a lithium-ion battery. The author could have just grabbed a lithium-ion USB powerstation, put it in his shirt pocket, run a USB cable up to his headlamp, and it'd have probably run for ages, even if the thing has -- and I'd believe it -- a completely garbage lithium ion battery. Hell, his cell phone would probably also run it. I keep a 100Wh power station in my backpack -- plus a few other devices with batteries that store a fair amount of juice and can put out USB-C PD power, and a ~400Wh power station and a few other batteries in my car. Even if the car batteries go dead, I have a 12V cigarette-lighter-to-USB-PD adapter that can put out IIRC 65W, and a second that can do straight 12V at 100W, which the 400Wh power station can simultaneously charge off of. As long as I can carry one of those, any device that can charge and function simultaneously works immediately.

I've got an AC-DC adapter that does 100W USB-C PD. That's capable of slurping up power at a pretty good rate, and as long as a device can intake that power quickly -- which I understand is becoming more-widespread due to GaN power-control circuitry -- it takes a lot less time to charge than it did back when USB provided a few watts. You can't get any devices (well, that I can find) that can provide 240W over USB-C PD yet, but the standard is now up to that point. I believe I read that the Framework laptop is particularly notable here today, comes with a charger that can spit out 180W over USB-C PD. Yes, it sucked to charge a lot of small electronic devices if it's off a USB-A connection putting out a few watts, but unless the device's battery is dead, the waiting issue just isn't such a big deal if you're talking about those much-larger numbers.

None of this is to say that there isn't a role for removable batteries. But I don't think that the story today is as simple as "lithium-ion non-removable batteries versus alkaline removables", which I kind of feel like the article is kinda focused on.

EDIT: I will add that one particular pet peeve is that there isn't a USB "battery" device class for USB powerstations to have their BMS report remaining voltage and charge to the host, which is part of why I'm annoyed at how hard it is to find 100Wh batteries in laptops today. If the USB guys would get on that, that'd really make USB power a lot nicer (especially since an intelligent laptop could have software that does a better job of estimating time remaining than the BMS in the powerstation). Maybe need to make it some special protocol that can also run over the USB power lines, as it'd also be nice to keep those charge-only cables to permit isolating devices informationally from devices that they're charging off of.