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Will a 5V 300mA USB device run safely off of 3 AA Batteries? Answered

I'm trying to make a 5V 300mA USB device portable, but I don't know how to measure/calculate milliamps for anything. What's the mA on 3AA Batteries? Pretty sure the voltage is 3.5, but please correct me if I'm wrong. Basically: if I chop the USB connector off and wire the device to 3 AA's, will the device operate safely, or will it get damaged?

2 Replies

gmxx (author)2009-09-18
Re-design (author)2009-09-18

3 x 1.5 = 4.5 volts. The mA rating is different on diff. types of batteries. The specs on usb rate the voltage from 4.5 to 5.25 approx. I don't remember exactly. So it's at the bottom of the usb spec. 4 batteries would be 6 volts and that would be over the rating and would need some regulation back down to 5 volts. Whether or not it will work depends on the device in question. Very few things would be damaged by too low a voltage so it would be okay to just try it as an experiment. The batteries probably won't last very long but it's an experiment.

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