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How can I wire a usb port to a preexisting battery pack and make it charge? Answered

I have a speaker with a battery pack already connected and giving power to the speaker, but I want it to also give power to a connected USB device so that it can charge from batteries while it plays.

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mpilchfamily

Best Answer 5 years ago

It won't be as simple as putting a regulator between the batteries and a USB connector. You will need a boost circuit to take the 3V from the batteries and boost it to the 5V 500mA needed for a USB charging port. But using such a converter will pull a lot of power from those little batteries and drastically reduce the run time of the batteries.

Your best option would be to buy a MintyBoost kit.

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sailorondatea

4 years ago

sth like this should do
http://www.aliexpress.com/item/Free-Shipping-DC-DC-Converter-Step-Up-Boost-Module-3V-To-5V-1A-USB-Charger-For/809914052.html

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verence

5 years ago

Not enough information. Is the USB device connected to the speaker device by USB? I.e. is the speaker actually a USB sound card or is the USB device normally not connected to the speaker / battery pack? What is the voltage of the battery pack? Do you have any experience with linear and/or switching regulators. How much current does the USB device need to be charged?

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metalshifletverence

Answer 5 years ago

The speaker does not have a USB built in. It puts out through a normal audio jack. The battery pack is using 2 AA batteries. I don't have experience with regulators, but I comprehend easily.

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verencemetalshiflet

Answer 5 years ago

See mpilchfamily'sanswer. 3V from 2AA (actually more like 3.4V when full, 2.4 when almost empty) are not enough to charge via USB. You need a step up converter. And the batteries wont last long. The energy stored in alkaline AAs is nothing compared to the energy stored in LiPo accumulators of cell phones. The facts that the step up converter and the process of loading itself both lose energy don't help either.