The intro will just explain one thing: why I decided to make this.
When I go on long trips, I like to be prepared. I also like to listen to music (when awake on that trip.).
Recently, I got a Android smartphone, and like all smartphones; the battery won't last more than eight hours.

This summer (2013) I am going on a 14 hour bus ride. So there's my problem: Too little power, no job,  and real external battery packs cost upwards of $50. 

So, I made my own; with a bit of help from the fellow evil scientists of the internet.

Step 1: Parts.

To build this pack, you will need:
-A brain, some logic, and common sense.

- A "size D" four-battery case.

-A pack of Diodes.

- A USB cable to your device.

- A multimeter.

- Extra wiring (just in case).

- Electrical tape.

-And of course, size D batteries.

All of these things (besides the first) can be found at a hobby store (such as Radioshack).
If you feel a little uncomfortable jumping into this, check out this Instructable on some basics.
some phones need these wires connected with resisters to indicate to the phone it is pluged into a charger
Hmmm...I didn't know that. Point taken, although this setup works for my relatively new phone.
lucky break then
<p>Why not just try to <a href="http://www.techsive.com/2015/10/how-to-make-your-smartphone-battery-last-longer.html" rel="nofollow">make the smartphone battery last longer?</a></p>
What about using a usb dc charge booster they can step up 1v to the 5v u need there about a dollar a piece on ebay. You could eliminate the need for a wire. Good project overall, keep on chugging.
you should use a power source closer to 5 volts
<p>4 D cells @ 1.5 volts each in series = 6.0 volts - 0.7 volts from the diode = 5.3 volts. Voltage should be acceptable.</p><p>Typical alkaline D cell capacity is around 10,000 mAh. My cell phone battery capacity is 1540 mAh. 10000/1540 = 6.49. Theoretically, I could recharge about 6.5 times, but in real usage it won't recharge that much.</p>
I should, it would be ideal; but this was the best I could find in Radioshack. I didn't have the time to buy online either.
<p>great proj. i'll make something like this soon.</p><p>please tell me how much charges usually take to dry the batteries.</p>
They have 50,000 mah external batteries on eBay for $20. I'm going on a school trip to DC in the spring and am going to charge peoples phones for money, I don't expect to make much but hopefully I can make some extra cash.
<p>How did that business venture work out for you, anyway?</p>
Nice instructable! which app do you use for the notification of battery charging?
Sorry for the late response, but to answer your question; <br>&quot;Battery Widget Reborn&quot;.
ah you need the resistors on the usb data lines most new phones do now
This charger was made for the sole purpose of charging the phone. The wires for data transfer inside my USB cable are completely ignored and cut away.
why do you have the diodes
My phone won't recognize it's charging without them; most likely because it wasn't without them. <br>I only had it plugged in for less than 30 seconds, but I didn't want to to risk a $500 phone over a simple experiment (turned instructable).

About This Instructable


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Bio: Supercalifragilisticexpialidocious.
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