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The Li chemistry produces much higher voltages and so would require step down circuitry to function as a direct replacement for AA/AAA. If you are talking about

The Li chemistry produces much higher voltages and so would require step down circuitry to function as a direct replacement for AA/AAA. If you are talking about form factor, then there are a lot of similar size or smaller cells available.

TeMPOraL 4y ago
I'm talking about having rechargeable AA/AAAs with higher power density, possibly using the same chemistry as in phones, laptops, drones, etc., so the industry could cut down on the amount of variation in sizes and connector types (which could possibly make the batteries somewhat cheaper thanks to less variation in manufacturing - though I suppose the price driver is still the chemistry). What's the minimum voltage we could get without intervention? I'm not well-versed in batteries, but I do recall that a typical Li-Ion cell has 3.7V on output, which might be tricky to fit into one AA/AAA, but isn't that far from two AA/AAAs. While there's no standard way for devices to accept multiple AA/AAAs, to a first approximation, a Li-Ion cell reformatted into a shape of two AAs with ~1-2mm "space" between them, would fit all my remotes and a third of my children's toys - so I could see a "Li-Ion double AA" working as a product, provided it could shed that 0.7V somewhere. The biggest problem would be devices accepting odd number of batteries.
- butterknife 4y ago
  There might be some market but anecdotally, AA/AAA as a widely accepted platform, and for that matter replaceable batteries in general, seem to be a thing of past. I do have devices where the 2xAAs are in a column configuration. Edit: Replaced remote with devices (it's a keyboard not a remote)
- detaro 4y ago
  There are standard formats for cells in Lithium-based chemistries, but they are different sizes then the Ni-based ones because of the entirely different voltages. How (not) commonly they are used tells you something how much industry cares about avoiding many different sizes. (part of it is probably also that round cells are space-inefficient in devices that aren't tube-shaped - most common consumer use cases where the consumer handles individual cells are flashlights and vape devices, and some markets do have proprietary designs as de-facto standards) Some manufacturers also make Li-Ion replacements for multi-AA devices, but thats then specific to manufacturer and device and the exact placement it expects.
- rjmunro 4y ago
  They sell double-AA sized rechargeable batteries for XBox controllers. https://www.xbox.com/en-GB/accessories/batteries-chargers/play-and-charge-kit https://www.xbox.com/en-GB/accessories/batteries-chargers/pl... This specific battery is unlikely to work for other devices because the controller has an extra connector, presumably to detect it and control charging (which happens over a USB cable). You'd at least need an XBox controller to charge it.
- nicoburns 4y ago
  I think the issue is that li-ion isn't that much better than NiMH as to be worth it. It's also worth noting that there are already standard sized Li-ion batteries. 18650 batteries (so called because they are 18mm diameter by 650mm long) are the most common, but there are a bunch of other standard sizes. These are commonly used in things torches (flashlights) and headlamps.

TeMPOraL 4y ago

I'm talking about having rechargeable AA/AAAs with higher power density, possibly using the same chemistry as in phones, laptops, drones, etc., so the industry could cut down on the amount of variation in sizes and connector types (which could possibly make the batteries somewhat cheaper thanks to less variation in manufacturing - though I suppose the price driver is still the chemistry). What's the minimum voltage we could get without intervention? I'm not well-versed in batteries, but I do recall that a typical Li-Ion cell has 3.7V on output, which might be tricky to fit into one AA/AAA, but isn't that far from two AA/AAAs. While there's no standard way for devices to accept multiple AA/AAAs, to a first approximation, a Li-Ion cell reformatted into a shape of two AAs with ~1-2mm "space" between them, would fit all my remotes and a third of my children's toys - so I could see a "Li-Ion double AA" working as a product, provided it could shed that 0.7V somewhere. The biggest problem would be devices accepting odd number of batteries.

butterknife 4y ago
There might be some market but anecdotally, AA/AAA as a widely accepted platform, and for that matter replaceable batteries in general, seem to be a thing of past. I do have devices where the 2xAAs are in a column configuration. Edit: Replaced remote with devices (it's a keyboard not a remote)
detaro 4y ago
There are standard formats for cells in Lithium-based chemistries, but they are different sizes then the Ni-based ones because of the entirely different voltages. How (not) commonly they are used tells you something how much industry cares about avoiding many different sizes. (part of it is probably also that round cells are space-inefficient in devices that aren't tube-shaped - most common consumer use cases where the consumer handles individual cells are flashlights and vape devices, and some markets do have proprietary designs as de-facto standards) Some manufacturers also make Li-Ion replacements for multi-AA devices, but thats then specific to manufacturer and device and the exact placement it expects.
rjmunro 4y ago
They sell double-AA sized rechargeable batteries for XBox controllers. https://www.xbox.com/en-GB/accessories/batteries-chargers/play-and-charge-kit https://www.xbox.com/en-GB/accessories/batteries-chargers/pl... This specific battery is unlikely to work for other devices because the controller has an extra connector, presumably to detect it and control charging (which happens over a USB cable). You'd at least need an XBox controller to charge it.
nicoburns 4y ago
I think the issue is that li-ion isn't that much better than NiMH as to be worth it. It's also worth noting that there are already standard sized Li-ion batteries. 18650 batteries (so called because they are 18mm diameter by 650mm long) are the most common, but there are a bunch of other standard sizes. These are commonly used in things torches (flashlights) and headlamps.