> Nickel metal rechargeables are a good AA/AAA substitute for devices designed to tolerate their lower voltage.

Any device that can't is arguably broken as designed. Much of the energy (the majority, in a higher current application) in an alkaline battery is found under 1.2V.

See discharge curves: https://lygte-info.dk/review/batteries2012/Duracell%20Ultra%...

NiMH actually stays above 1.2V longer for all but the lightest loads: https://lygte-info.dk/review/batteries2012/Eneloop%20AA%20BK...

Unless the device was designed around the alkaline discharge curve! Smoke alarms rely on the lower voltage to give sufficient warning when the battery is low, and mine refuses to operate at all when powered by a rechargeable battery.

Try lithium-based AA/AAA rechargeables. These worked wonders for my finicky Instax Camera which refuses to use regular NiMH AAs because their voltage is too low.

The issue with these is the low battery warning. Once the voltage starts dropping you don’t have much time to notice. Not a problem for active devices, but things like door sensors may give you just a few days between 80% and dead.

Absolutely. Different battery manufacturers use different discharge profiles, some gradually lower voltage in a few steps, others may just die with almost no warning, so it might take a few tries before you find a brand that works for your device.

Had to use my old TI 89 one day. Haven't used it in 10 years. Took it out of storage, put in 4 AAA usb-c rechargable batteries, worked like a charm. Could you do the same with your hard to replace custom battery?

Any consumer electronic using standard format batteries is superior by default. Because 10 or 20 years from now, it still have brand new full batteries lying around.

I have an early digital video camera with a genius design. It came with a custom rechargeable cell in the battery compartment. But the compartment _also_ supports regular AA batteries.

Most petzl headlamps are setup this way for a small lipo pack or 3 aaa's. It's great

Brother label printers used to support this up until a couple of years ago at least but sadly the most recent models have stopped having the AA compatibility.

Absolutely the best of both worlds. You can find a shop selling AA everywhere in a pinch and keeping a few in the camera bag is easy too.

I‘ve done this with my HHKB. Great solution.

Point taken. What's your review of those batteries with a USB C port? I've always avoided them because of the reduced capacity, price (5 or so years ago) and that I assumed they would have a constant voltage output making it impossible for devices to give you an accurate battery level measurement.

I'm not magic; can't replace built-in batteries without a soldering iron (or at least, relatively uncommon replacement parts).

As always, engineering tradeoffs are involved. I was recently looking for a casual point-and-shoot camera from the ~2010s, but all the slimline ones used flat lithium removable batteries (as only the bulkier ones have space for AAs).

> it intrigued me that you prefer replaceable AA batteries to built-in rechargeables

I share this preference. Replacing a battery has a device back in a working state a couple orders of magnitude faster than onboard charging, and when built-in batteries wear out, replacement is often difficult to impossible.

I always use NiMH rechargeables; alkalines are wasteful and sometimes leaky.

I too was surprised by this view when I started at Oculus, where the game controller folks who had come over from Xbox were adamant that players would rather swap in a fresh pair of AAs than plug into a charging cable.

Personally I've never come around to their side of things, although I do recognise the inconvenience of charging cables while you are using a peripheral (Apple Mouse charging port location especially :D )

For me, I'll always choose a device with standard, user-replaceable batteries over a built-in battery.

1) If the device battery is dead, I can swap it out in seconds and be up and running immediately.

2) Built-in batteries fail, and replacing them ranges from difficult to near-impossible and often involves damaging the device's casing to get the built-in battery out.

When I'm spending $100 on a computer mouse, I'd really like it to last longer than the life of the battery and not have to destroy the casing to get to the battery to replace it.

Yeah. Though to be fair, the alternative in the controller space in that era was hot-swappable rechargeable battery packs - a ton of 3rd parties provided them for Xbox 360 controllers.

IMHO Sony nailed this pretty perfectly 30 years ago on devices like the Discman: Have a footprint which can support a number of standard batteri(es), but engineer it so it also accepts and detects a specially-designed NiMH pack. When the special batery is present, allow the battery to be charged anytime external power is provided.

Now you have the best of both worlds: Economical rechargable use for the 90% of the time that the user's in their normal routine, and easily ability to swap temporarily to universally-available alkalines in exceptional situations.

Note: When I had one of these, I just used my own NiMH AAs and jammed a folded-up piece of cardstock against the detection switch, which worked perfectly fine.

IMO just having the battery pack replaceable without tools is what matters more than using a standard one. As long as the device is even remotely popular there will be cheap replacements available.

Regarding #2 the fact that probably the majority of battery-powered non-toy devices now are designed not to ever have their battery serviced is indicative of a (in my opinion) diseased mindset of disposability. Each of the components including battery and other wear parts are only spec'd to last about 12-18 months. We're being conditioned (by one-year warranties and by the lack of repairability) to think that it's normal and expected that you discard and replace everything smaller than a car every 18-36 months, and a car every 7 years or so because "obviously" anything older than these milestones is "obsolete anyway."

I still use my Xbox 360 sometimes, and the only controllers that still work are the ones with AA batteries. The rechargeables have long since died completely.

I, too, prefer disposables, but for a somewhat different reason. One very commonly used surgical item is a sterile suction/irrigator. It's sealed with 8 AA's at the factory, used for 2-3 minutes during laparoscopic surgery, and disposed of. So pretty much anyone who works in a surgical suite that does laparoscopy has a personally unlimited supply of AA's that would be thrown away anyway.

Years ago when I worked in live audio we had a similar setup. Zero tolerance for a performer's mic pack dying mid show because a low battery indicator wasn't calibrated right or someone incorrectly tracked how many hours a particular set had been used, so it was fresh-from-the-package alkaline AAs installed before every set, and a virtually unlimited supply of half-charged disposables to take home afterwards. Plenty would get reused for internal equipment checks and sound checks, but there were still more than enough to go around.

At the time (well over a decade ago) there was still lots of skepticism around recharagables and the extra process involved in dealing with them... but the tech has gotten lots better since, at that time even low-self-discharge was sort of hard to find. I'm sure much of the industry has moved over by now.

When it has to be factory-sealed as sterile, there is no point in using a rechargeable.

I would love to end the senseless waste in surgery, but The Powers That Make Our Lives Suck For No Reason want everything to be single-use sterile objects.

Same but with portable infusion pumps. They were always sent out with fresh sets but worked for days on a single set often leaving a lot of life.

Isn't that a biohazard strictly speaking? I'm not sure you want to get caught stealing used surgical equipment for home use.

It’s quite literally trash; I could hardly be described as stealing it.

The batteries are in a separate container that is attached to the bag of saline used for irrigation. It’s not in the surgical field.

> It’s quite literally trash; I could hardly be described as stealing it.

Note that legally trash is still owned, usually by the person or entity which produced it, so it’s technically stealing. (Whether anyone cares is a different thing. If you picked bank letters instead of barely used batteries…)

My Logitech G603 runs quite happily on Eneloops, for the best of both worlds.

Replaceable rechargeable batteries are the best choice (assuming the weight doesn't bother you).

You can quickly swap in a new pair, and recharge the other one. Some mice can even charge the batteries themselves. You get the best of all worlds.

I always have at least a half-dozen NiMH AA batteries sitting charged in the drawer ready to go. When the mouse stops working, I grab a couple of charged batteries, slap them in, put the drained ones in the charger and then carry on with whatever I was doing. With a built-in battery, when the battery goes dead, I have to mess around with finding another mouse while this one charges.

(Yeah, the computer tells me when the mouse battery is getting low, but I do not have the discipline to remember to plug it in hours later when I'm done with the computer for the day.)

The thing with AA is that it gives you options. You can use rechargeable in it if you’d like. Avoiding proprietary batteries is a good thing because they are not always available or easy to service for the end user compared to AA.

For certain activities like hiking having AA or AAA is preferred. If they run out of charge they are trivially replaced with a light weight inventory and this is probably sufficient to last your trip.

> cable on hand vs keep some charged batteries on standby.

You don't need to keep them, you get warned many days in advance, so an overnight recharge of existing batteries works just as well

If you have a a device that does not tolerate the lower voltage, check out NiZn rechargables. They top out at ~1.7 V when full and keep their voltage quite high until they are almost flat. (At which point they should be immediately recharged, they don't take deep discharge well.)

I use them almost everywhere nowadays. Most devices tolerate the slightly higher voltage and even expensive hardware usually cheaps out on proper battery circuitry.