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This might be a stupid question. But how much current can you safely draw from a AAA battery.

I am currently powering my project from a worktop power supply and it draws at 5V 0.45A during normal operations and peaks to 0.7A. Now I need to make it portable and looking for the right battery. I need to keep my project as compact and light weight as possible. I was thinking of using four AAA batteries or suitable Li-ions to power it on the go. The max duration I expect is 1hr but I will be satisfied with 45 mins.

If you have any other suggestion of powering the project please help me out.

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  • \$\begingroup\$ I wouldn't try to pull 700mA from an alkaline. NiMH or even NiCd maybe. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Dec 1, 2014 at 0:34
  • \$\begingroup\$ @IgnacioVazquez-Abrams Do you think Li-Po may be a suitable? maplin.co.uk/p/crp2-lithium-camera-6v-battery-1-pack-n02bx \$\endgroup\$
    – Flood Gravemind
    Dec 1, 2014 at 0:37
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    \$\begingroup\$ LiPo would definitely be suitable, provided it's at least 800mAh. But that's not LiPo, that's LiMnO2, and would probably perform worse. Look at Li-ion 18650s instead. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Dec 1, 2014 at 0:38

1 Answer 1

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The maximum current depends very much on the chemistry of the battery.

The capacity of the three main (no Lithium) batteries is approximately:

  • Zinc-Carbon: 540mAh
  • Alkaline: ~1000mAh
  • NiMH: ~900mAh

The current limit and capacity of any specific battery can be found in its datasheet. For instance, the Duracell MN2400 has the following nice graph:

enter image description here

So you can see from that, 500mA would start to drop off significantly in voltage after around 1 hours. 1A would last about 30 minutes, if that. So 700mA would be somewhere between there.

Also, from the datasheet, you can find the impedance. 250mΩ in this case. At 1.5V full charge you should be able to draw up to (I=V/R) around 6A from it. It'll probably not like it, and get rather warm, or explode, but 500mA - 1A should be no problem.

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  • \$\begingroup\$ I need 6Vs from the chart I can see that its 1.5V so 4 alkalines would be pumping between 100mA to 150mA each and that should keep me safe from mythbuster type explosion am I right? \$\endgroup\$
    – Flood Gravemind
    Dec 1, 2014 at 0:43
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    \$\begingroup\$ @FloodGravemind: KCL says that all cells need to supply the same amount of current when placed in series. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Dec 1, 2014 at 0:48
  • \$\begingroup\$ Note the battery voltage in that chart. If you need six volts, then for any reasonable battery life you will need more than four batteries in series. In this case, designing for 1.0V end of life voltage would be appropriate, and then you would need six batteries. \$\endgroup\$
    – Paul Elliott
    Jan 26, 2017 at 18:18

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