I've been messing about with some electronics stuff and want to be able to charge phones, tablets and similar stuff from AA batteries, just in case I have a use for doing so one day, such as if I'm camping for some bizarre reason, or just to see how long the batteries last to get a good idea on how good a power source they may be for other stuff. It should also be able to provide more power than most emergency chargers (regulator can take up to 3A). In case you're wondering, the batteries are just hooked up to a 5v regulator and then that's connected to a barrel connector that goes into a barrel to USB port thing.
Measuring it with a multimeter, slightly more than 5v comes out the regulator (still within the +5%/-5% range) and it charges an emergency phone charger and camera, but a phone and tablet will not react to being plugged in. I heard in the past that doing something with the data pins is required but I'm not sure what and the port doesn't look like it's easy to open up or anything. On top of that, there will only be a positive and negative going into the port itself.
So, if possible, please state why it may not be working with those devices but works with some other stuff. If it matters, the phone is a Samsung Galaxy GT-S5830 and the tablet is a Kindle Fire HD [First Generation].
Added (1). It is also capable of powering a Pi. Of course, that all makes sense as the Pi will ignore any data pins, just like the emergency phone charger.
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