100+ half-spent AA batteries, what do?
November 17, 2020 8:35 AM   Subscribe

I maintain battery-operated sensors far from my main work site. These get fresh alkaline AA batteries every 5-6 weeks to ensure they're always working, leaving me with way more partially-used batteries than I can use in stuff like computer peripherals. They're still putting out 1.5V, but I know that doesn't tell me much about how much life they have left. What can I do with these? (I'm working on retrofitting the sensors to solar, but I still have a pile of batteries I'm trying to avoid just recycling. Rechargeable AAs are not a good option because the batteries are exposed to freezing weather.)
posted by momus_window to Technology (15 answers total)
I think this would be a great thing to put out on a local free site (Buy Nothing, Freecycle, local marketplaces, etc.). Just give full disclosure that they've been used, but still work.
posted by hydra77 at 8:47 AM on November 17 [5 favorites]

Scout troops or summer camps would use these for flashlights. Half a battery is a lot for an LED.
posted by thenormshow at 9:09 AM on November 17 [4 favorites]

Yeah, if nearly-empty bottles of dog shampoo get snapped up on my Buy Nothing group, people will go nuts for these batteries. Maybe break them up into bags of 20 if you can? That might make them move faster.
posted by corey flood at 9:11 AM on November 17

If there's a local organization that's collecting Christmas gifts for kids, I'm sure they could use a whole bunch of AA batteries to hand out with the electronic gifts.
posted by jabes at 9:17 AM on November 17 [7 favorites]

My employer’s policies mean a community donation is not allowed (although unlikely to be noticed...). Please share other options if you’ve got them.
posted by momus_window at 9:50 AM on November 17

I have been using generator bike ligghts for years, so I am not sure whether bike lights take AA batteries any more, but definitely ask your local community bike shop. If they need them, they can probably keep up with you.
posted by aniola at 9:59 AM on November 17

If you can't do a community donation, can you still freecycle? Otherwise, maybe ask around among your co-workers and see if there are others who could also use them at home. (Easier to do when we still met in offices.)

Another option for personal use is lighting - we had a lantern style flashlight that provided a nice ambiance but burned though batteries pretty quickly. Maybe electric candles for the windows? Although buying something to use up free batteries doesn't make sense unless it is something you will keep and use over the years.
posted by metahawk at 10:15 AM on November 17 [1 favorite]

Are you artistically minded? Use the batteries to create public art. Perhaps some kind of memorial using electric candles as metahawk mentioned.
posted by oxisos at 10:32 AM on November 17

Can you, like, put them in the break room at work in sacks of two dozen?

At work we apparently accumulate a 5-gallon bucket of "retired" but not-yet-drained AA batteries (from card-readers on equipment closet door lock readers) once or twice a year.

I just found out about this, and I desperately want to bring it home: even if I only get a few months out of them, it's better than land-filling them, and also I don't have to buy batteries!
posted by wenestvedt at 10:36 AM on November 17 [3 favorites]

Consider buying a USB backup power charger that uses AA batteries, such as this one.

You could also purchase a large portable battery bank, such as this one, and use it to recharge your phone or work peripherals. When the large portable battery bank gets low, power it up again with your ever-growing, partially-used stock of AA batteries.
posted by cursed at 11:14 AM on November 17

Not to XY-problem you, but is there a particular reason you're not using lithium primary cells for this (e.g. Energizer Ultimate Lithium)? They last basically forever, operate in low temperatures, and they even keep their voltage better than alkalines.
posted by neckro23 at 12:58 PM on November 17 [1 favorite]

The break room solution maintains the appearance that the batteries are being used for work, and enough people have reasons to come in that they should disappear.

Not to XY-problem you, but is there a particular reason you're not using lithium primary cells for this (e.g. Energizer Ultimate Lithium)?
I have to check these periodically anyhow to download data and make sure they're still working, should have made that clear. And if I'm spending that kind of money on batteries, we should just buy solar panels.
posted by momus_window at 1:54 PM on November 17 [1 favorite]

These should be great around the office for mice and possibly wireless keyboards.

When I was helping a friend doing semi-pro wedding photography back in the 70s, he would use batteries in a Vivitar flash. When they got too weak to work well, he’d pull them out and give them to kids to take to their parents; he said there was plenty of juice for battery-powered toys (at least of that era).
posted by lhauser at 7:12 PM on November 17

8 AA batteries in series will give you the 12v you need ttyl power a CPU fan, which could
Be nice for cooling the people in your office who want that.

Here's an 8-AA battery holder for cheap.
posted by amtho at 9:26 PM on November 17

It sounds like these would be perfect for small LED headlamps/flashlights/lanterns or (infrared) remote controls. They last so long to begin with that even if the cells are half drained they'll still last for many hours of use.

Without testing them under load, you can't really tell how much capacity is actually left since an alkaline cell's voltage will recover after sitting for a bit unless they are nearly dead. If you test the voltage while drawing a couple of milliamps instead, you'll have a better idea of how much energy they really have left to give. The major manufacturers all have data sheets with discharge curves that you can use to get a reasonably accurate idea of where they really stand.

Where it would get annoying is trying to use them for things that have a relatively high current draw like camera flashes or MP3 players or game controllers since alkaline cells provide much less total energy when they are pushed hard than they will in a lower power device. IOW, trying to draw twice the current will result in less than half the life you'd get with a device drawing half the current. In terms of office equipment, you'll have much better luck with a wireless keyboard than a wireless mouse, for example.
posted by wierdo at 3:54 AM on November 18

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