Q&A: Can you power a Raspberry Pi from two AAA batteries?

usbdcQ: I want to build a portable Raspberry Pi project but want to keep it small. Can I power a Raspberry Pi from just two AAA batteries?

A: Yes, but not for very long. The Raspberry Pi needs a 5VDC input at around 500-700mA. With just two AAA batteries, assuming you’re using NiMH rechargeables, you’ve only got 2.4VDC nominal, so at the very least, you’ll need a DC-DC step-up voltage converter (pic). These are cheap enough on eBay – you should be able to get a decent one for under $5 including shipping.

But that’s just half the problem. The other half is the low-capacity of AAA batteries. If you’re lucky, you’ll find AAA cells with capacities approaching 900mAh. Now assuming your DC-DC converter has a power conversion efficiency of approximately 90%, those batteries will need to deliver around 3.8-watts of power at peak performance levels. That means you’ll be draining those AAA batteries at 3.8 / 2.4 or around 1.58-amps. With their 900mAh capacity, that’s going to give you around 0.9 / 1.58 or 0.56 hrs – a bit over 33 minutes if your Raspberry Pi is running at full tilt.

If the Pi is only running at moderate levels, you might be able to stretch the battery life out to an hour at best.

Bottom line, there’s only so much power you can get into a small AAA-battery size package. With AA-size NiMH batteries hitting 2700mAh, you could achieve three times the runtime of AAA cells – that’s 90minutes worst-case or as much as three hours with the Pi running at moderate power levels.

They might be a better option to think about.

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