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I know it is possible to replace a AAA battery with a power source, and that it is possible to use AAA batteries as AA batteries (these are what I find when I google this question).

My problem is that I'm building an electronic prototype that's way too big for my purposes. About 50% of its size is the battery and battery case (it uses AAA). I was wondering if it would be possible to take the specs of a AAA battery (volts, current, power) and find a similar battery that was much smaller to replace it (perhaps one of those tiny disc ones). Then all I would have to do is solder the voltage + ground lines to it?

My EE knowledge is limited but I think this should work. Has anyone else given this some thought or know the best way to approach this, such as what batteries might work or where to find them?

Edit: The project uses 1 triple A battery

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    \$\begingroup\$ Maybe N cells? en.wikipedia.org/wiki/N_battery \$\endgroup\$ – Ward Jun 7 '16 at 3:35
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    \$\begingroup\$ "It's a consumer product that I'm modifying" - what is it? \$\endgroup\$ – Bruce Abbott Jun 7 '16 at 4:24
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    \$\begingroup\$ @Kevin How about AAAA batteries? Yes they exist. \$\endgroup\$ – Bradman175 Jun 7 '16 at 4:49
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    \$\begingroup\$ @Bradman175, can I be certain that that hooking these up won't cause the battery to explode regardless of the current? Or do I need to measure the current first? Sorry that I took one ECE class like 3 years ago and am trying to re-learn all this. (Pretty sure overdrawing current would only cause it to empty quicker...?). Am I certain I would only need to use one of them and just expect it to diequicker than a AAA would? \$\endgroup\$ – Kevin Jun 7 '16 at 4:53
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    \$\begingroup\$ Duracell AAAA or Energizer . See Wikipedia \$\endgroup\$ – Russell McMahon Jun 7 '16 at 8:38
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As stated in the comments, you can use AAAA batteries (42.5mm x 8.3mm diameter instead of 44.5mm x 10.5mm).

Puting a AAAA instead of a AAA certainly won't make anything explode. Both AAA and AAAA are alkaline batteries, so they have the same voltage. If the product had originally one AAA, just use one AAAA instead. You'll be fine, except that the capacity is much lower (about half), so it will die quicker, but there is no risks involved, neither for the device nor for your health. There is no chance the consumer product you indicate exceeds the current capability of such batteries (unless it could run for only 10 minutes with an AAA battery).

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  • \$\begingroup\$ Confirming that this was a suitable replacement -- tested and checks out \$\endgroup\$ – Kevin Jun 10 '16 at 10:25
  • \$\begingroup\$ Gg. Maybe there will be AAAAA batteries in the future. \$\endgroup\$ – Bradman175 Aug 24 '16 at 23:11
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The AAA alkaline battery has 1.5V nominal voltage and 1100 mAh nominal capacity. That's 1.65 Watt Hours of power. You will have a hard time finding a smaller battery that exceeds these specs. Coin cells will have a fraction if it. Lithium coin cells like the CR2032 has 3V at 250 mAh, but a high internal esr making it less useful than the AAA for higher draws. It's roughly half the power, in theory. In practice it's much less powerful.

Smaller batteries will not have the raw power. And will be more expensive. The only reason you should go down is if space is at a premium or if you can deal with the lower capacity.

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    \$\begingroup\$ I think you say "power" when you mean "energy" \$\endgroup\$ – markrages Jun 7 '16 at 4:35
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    \$\begingroup\$ Given the absurdly high ESR of a coin cell I'm pretty sure he does mean "power" - the energy content does also suffer, but only (roughly) proportional to cell volume. \$\endgroup\$ – Brian Drummond Jun 7 '16 at 10:32
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You do not reveal either the voltage (how MANY AAA batteries?) nor the current your project draws. If you don't know how much current your project draws, then you REALLY need to measure it so you know what you are dealing with.

Since we know neither the voltage nor the current here, we have no clue whether this might be a useful suggestion: Many current gadgets use modern rechargeable polymer lithium ion batteries. They are available in smaller sizes than AAA. And in different shapes (typically quite flat) which may be helpful for your profile design.

Typically, a smaller battery might be capable of the same voltage output, but it will have a shorter practical operating time. So it is always a trade-off of requirements.

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  • \$\begingroup\$ After suggesting "rechargeable polymer lithium ion batteries" (maybe mention lithium-ion polymer batteries are also known as LiPo) you should probably mention that over-charging, over-discharging etc. can cause catastrophic failure, including fire en.wikipedia.org/wiki/Lithium_polymer_battery#Safety, and so the OP would need to consider some electronics to monitor it. AFAICT, the OP edited their question after you answered, to say it is one AAA, so a LiPo battery would also need something to reduce its nominal 3.7V to 1.5V. So your current answer has become a bit misleading. \$\endgroup\$ – gbulmer Jun 7 '16 at 10:57

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