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I have a cosplay project where I'm creating a "Megaman" aka Rockman type of arm cannon (it's actually based on DC's Cyborg). Anyhoo, I've been weighing options like using 3xAA alks or 4xAA nicd (or otherwise 1.2V)--inclcuding various combinations of less or more cells with a voltage regulator; boost up or step down as appropriate.

there are 4 lighted segments (15 leds of WS2812B x 4). I also of course have to power the Arduino Nano as well. I'm flexible on led brightness so I'm just going to tune it [code it] to whatever looks adequate for my purpose. I am aware of the 50ma draw of these units at full brightness

My original plan was to just keep it easy (read lazy) and use 3 AA alks per 2 segments, and another 3 so the nano can have it's own supply. So 9 cells in total (without any additional regulation). Before you judge me--weight, volume, and especially area are definitely big factors in my decision.

So that's a long way to get to my actual question. Has anyone used these new types of USB rechargeable batteries? They seem to have the best of both worlds with the power of an alkaline but the consistency and sustainability of a NiMH /NiCD as they have internal regulators that produce a steady 1.5v (until they don't--which I'm more than cool with)

Short of having a properly regulated 5v power supply, are these a good option if I want to be slightly more responsible than throwing in whatever other AAs I have lying around? They definitely check the box on my space/mass requirements. I'm sure they do fine with most consumer electronics, but as far as arduino and any other custom/hobby 4.5-5v applications how reliable are these? Even if you haven't used them before I'd be curious of your thoughts. I'm a novice at best when it comes to elec engineering.

Yes, they are expensive. Thanks all!

examples: https://www.amazon.com/Rechargeable-Batteries-Quick-Charge-Integrated-Protection/dp/B07F27PK2M/ref=sr_1_5?crid=1RTQUCZYG4KBM&dchild=1&keywords=usb+aa+batteries+1.5v&qid=1588280164&sprefix=usb+aa%2Caps%2C242&sr=8-5

https://www.amazon.com/Blackube-Rechargeable-Batteries-Lithium-1500mAh/dp/B07D9K2H9H/ref=sr_1_11?dchild=1&keywords=usb+aa+batteries+1.5v&qid=1588282813&sr=8-11

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  • 1500mAh is considerably less than what you'd get from a normal NiMH. And for the price of them you could get a pack of normal NiMH and a proper charger.
    – Majenko
    Commented Apr 30, 2020 at 22:04
  • I think you can get a good LiIon or LiPo battery and a fitting charger/voltage regulator module for less than that. And it could output directly 5V, so you wouldn't loose more power with an extra voltage regulator. Or are you somehow bind to using AA sized batteries?
    – chrisl
    Commented Apr 30, 2020 at 22:25
  • @chrisl I'm not necessarily stuck on AA, but I'm mounting them on the outer circumference of a 3" PVC pipe, aligned with the direction of the pipe openings. Imagine a small ammo bandolier around your forearm with nine 20ga shells surrounding...That's kind of what I'm thinking. So larger flatter batteries are going to have a weird footprint for my purpose. Mounting 9 or so individual AA battery holders seemed like a good way to make this look clean. The section of pipe is also on a spinning bearing, so the batteries have to be distributed somewhat evenly. A single large battery won't work.
    – Cradle2theGabe
    Commented Apr 30, 2020 at 23:44
  • If you want to fit it into PVC pipe, why not consider 18650 Li-ion rechargeable, it gives you anywhere from 2000 to 3500mAh with a single compact battery with 3.7v output. You could either add a boost converter or use 2 batteries feed into Vin of Nano.
    – hcheung
    Commented May 1, 2020 at 2:38
  • @hcheung I like this. I'm actually thinking I would do two in a series and pop in a 5v reg since I'll be saving space with 2 cells instead of 3 or 4. Also an expensive option but other than that it's a good fit.
    – Cradle2theGabe
    Commented May 1, 2020 at 6:29

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Those "batteries" are actually a 3.7V¹ ~750mAh Lithium rechargeable cell with a 1.5V switching regulator and 5V charge circuit built in.

In about the same space as one of those, if you throw away the charge circuit and switching regulator, you can get a single 18650 Lithium rechargeable cell at 3.7V¹ (nominal) and three times the capacity. Two of those plus a small 5V switching regulator² would give you more power capacity and longer run time in a smaller space than the equivalent voltage of these strange "batteries".

¹ Nominal

² Use a good one with a Li-Ion battery protection circuit and maybe a built in 2S charger too for convenience

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  • Thanks for the context on the USB AA cells! Taking your advice on the 18650's.
    – Cradle2theGabe
    Commented May 8, 2020 at 0:10

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