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I want to purchase this power supply (battery pack) for mobile projects (I know, it isn't a lot of power), and I was wondering if, with a bit of modding, like adding a micro usb tip to the power or by placing this 5V regulator between the battery pack and the 5V GPIO pin, it could safely power the Pi.

I know that most of the Pi runs at 3.3 volts, but 5 volts is needed for the USB ports, so I went with the 6V one. They also have this 9v Snap Connector, would that be a better choice?

I'm very new to hardware and such so please bear with me.

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According to Raspberry Pi forums, you can supply 5V with a ±5% uncertainty, meaning you could supply from 4.75 to 5.25 volts. The 7805 voltage regulator should be okay for your project, for it could supply a max of 1A and it stays within that uncertainty. This leaves you with an additional 250mA for connecting a keyboard or something else that doesn't require much current. For more information on how to use the 7805, refer to this Youtube video.

To answer the original question, you should stick with 5V at all times, with the uncertainty as a means to protect itself from small spikes and dips in voltage.

  • Thanks! This answer was perfect and told me exactly what I wanted to know. – RPiAwesomeness Sep 14 '13 at 19:36
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    7805 needs minimum input of 7V. At 9V you would need a big heatsink to dissipate the 3-4W you are wasting in the regulator. – John La Rooy Sep 16 '13 at 10:56
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You have to be careful with those 7805's. If you remove power from the 6V side while a powered hub is connected for instance - the 7805 will be reversed biased. This is the archilles heal of the 78XX series. You can help it out somewhat by putting a reverse biased diode (anode to the 5V side) from the input to the output.

Additionally, the 7805 are old regulators, and need at least 2V drop, so you'd need at least 7V input.

There are linear 5V regulators that can work ok off 6V, but they tend to be more expensive. Also remember that 1V drop at 1A is 1W, so you'll probably need a heatsink.

I'd recommend searching for the LM2596 modules on ebay. More flexible and more efficient and probably cheaper. Locate the module close to the RPi, keeping the wires between the two shorter gives better stability. enter image description here

Make sure you adjust the output to 5V before you connect the RPi!

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