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Today's messenger bag has become the urban pickup truck. Crammed with gadgets, gizmos, and paperwork; just open up the flap and toss in more electronic ephemera. Now it's time for your message bag to pay back for its wanton stuff gluttony and recharge your stashed goodies as you lug your battery-powered electronics around town.

Get your messenger bag up to speed and equip it with a photovoltaic-powered charging circuit. Not just any photovoltaic panel will do, however. It needs to be lightweight, flexible, weatherproof, and powerful. Likewise, the connector for this solar-powered recharging system needs to simple, foolproof, and compatible with the largest number of your electronic gadgets. The thin film plastic solar modules from PowerFilm (formerly Iowa Thin Film Technologies) coupled with a USB female connector are the perfect combination for transforming your overloaded dolt messenger bag into a messenger bag loaded with volts.

Step 1: How to Make Your Own Juice Pouch

2 hoursCost: $45.03Very Easy

Parts List


  • A Messenger Bag (FREE)
  • Iowa Thin Film Technologies PowerFilm WeatherPro Series P7.2-75 (Jameco #228161; $39.89)
  • USB 6' Cable w/Female Connector (Jameco #222068; $1.65)
  • 78M05 Voltage Regulator (Jameco #192233; .19)
  • 0.47mF 50V Electrolytic Capacitor (Jameco #330464; .04; substitutes are OK)
  • 0.1mF 50V Tantalum Capacitor (Jameco #545570; .31)
  • Salvaged Plastic Project Box (FREE)
  • Clear Vinyl Sheet (craft store; .50)
  • Large Eyelet Kit (craft store; $2.45)
  • Alligator Clips
  • Wire

NOTE: There are four distinct subassemblies which constitute our Juice Pouch: (1) modified messenger bag, (2) photovoltaic panel, (3) voltage regulator, and (4) USB connector.

Step 2: Mod Your Bag

Depending upon the style of your messenger bag, you may or may not have to perform any or all of these modifications. Generally, the outside flap of the messenger bag should be equipped with a clear pocket for holding the photovoltaic panel. You can make your own clear pocket from vinyl sheet. Likewise, you will need several grommets or eyelets for routing your cables through the messenger bag. Add as many eyelets as necessary for connecting your charging "dock" with the voltage regulator and the photovoltaic panel.

Step 3: Fun in the Sun

Preparing the photovoltaic panel has been simplified by the manufacturer-attached solder tabs. These tabs are pre-wired as positive (+) and negative (-) terminals. Either solder directly to these tabs or use removable clips for greater flexibility in moving the panel in and out of the bag.

Determine the positive and negative terminals on the photovoltaic panel with a multimeter. Mark the positive terminal for easy identification.

Step 4: Voltage Regulator

Mount the 78M05 voltage regulator inside your salvaged plastic project box.

Step 5: Getting EVolts

The two capacitors must be soldered to the 78M05 voltage regulator. The positive lead of the 0.47mF electrolytic capacitor is soldered directly to the input lead of the 78M05 voltage regulator. Conversely, the positive lead of the 0.1mF Tantalum capacitor is soldered to the voltage regulator's output lead. Finally, the negative leads of both capacitors are soldered to the ground (GND) lead of the 78M05 voltage regulator.

Step 6: Get Connected

Snip off and discard the male connector from the USB cable. Open this newly exposed cable end and separate the four wires: red, black, green, and white. The green and white wires are USB data lines and they are not used. The red wire is connected to the output lead of the 78M05 voltage regulator. The black wire is connected to the voltage regulator's ground lead.

Step 7: Wire It

Connect the photovoltaic panel's positive terminal to the input lead of the 78M05 voltage regulator and the panel's negative terminal to the voltage regulator's ground lead.

Step 8: Test It

Place the photovoltaic panel in direct sunlight and test the voltage readings with a multimeter at these four points: photovoltaic panel terminals (you did this test in Step 2), voltage regulator input, voltage regulator output, and USB pin 1 + 4. The readings at the first two points should both be approximately 7 - 8 volts. The readings at the last two points should be exactly 5.15 Volts. If you obtain valid voltage readings, try connecting one of your USB-chargeable devices to the Juice Pouch's output USB female connector. During testing we found that iPod nano (first generation) and Sony PSP charged reliably with this setup. Unfortunately, we were not able to charge a Motorola RAZR V3 phone or an iPod shuffle (first generation).

Step 9: Charge!

If everything checks out, assemble the photovoltaic panel, voltage regulator, and wiring inside your messenger bag, hook up a suitable device and charge out there.
Ohhh.... I thought that you filled a messenger bag with Apple Juice.... Good instructable none the less!!
me too...or something like that i thought he meant a pouch...for juice. Good idea though!
Haha aparently I'm not the only one who thought this refered to "juice" the beverage instead of electricity.. : )
maybe aquarium tubing hooked up to a juice bag in the bag?
Very true. <br>I feel like there is a lot of interest in this idea... <br><br>Super compilation?
Just came up with a great idea.<br /> Lets figures out a way to fill the messenger bag with juice, and then you can hang with your friends and be like, &quot;Juice PARTY!!!&quot; :D<br /> -L<br />
We have unlimited juice? This party is gonna be off the hook!<br><br>-Buster, Arrested Development
&nbsp;I was thinking the Exact same thing!!<br /> <br /> We should get on this.<br />
Sorry, I'm kind of missing the humorous reference here :&nbsp;/
&nbsp;Well, &quot;Juice&quot; &nbsp;was&nbsp;initially&nbsp;meant as battery power, but we misinterpreted it as the fruity drink.
I understand the fruity drink part, as that's what I thought from the title too, I&nbsp;just don't get the &quot;juice party!&quot; reference.&nbsp; At least, I thought that was in reference to a movie, so I&nbsp;didn't get it..
I thought he meant juice too :(
Teamwork! *High Five*
same, i was really hoping for something to drink.. oh well, water it is.
&nbsp;It's as if everything you have can be modded to generate electricity these days...
i can mod a piece of wire to gemerate electricity...<br>you just need lots of wire and magnet (you know what it is)
i clicked thinking it would be literally a juice pocket. a poket for a juice box or something :D haha! but still very interesting
&nbsp;Thats what I thought too!
Nice job! This beats buying a pre-made bag for 3 times the amount this was made for! 5*'s!<br />
Dang! At first glance, I thought this was going to be about koolaid. I'm all thirsty now and haven't any pouches to fill with juice because this instructables is misleading. <br /> <br /> But is very awesome. I might build one myself so I can Juice my Gadgets.<br />
If you upped the complexity a notch, I think you could get the other items to charge reliably even in dark conditions!<br /> <br /> Basically, you'ld need a charging circuit for a super or ultra capacitor, and a joule theif/ DC to DC&nbsp;upconverter to keep consistent juice flowing in &quot;waves&quot;<br /> <br /> Should work, and may only add about $10 to the project if you source your supplies correctly.<br /> <br /> <br /> Pretty neat!&nbsp;&nbsp; Even if I&nbsp;did wonder &quot;why would you make your messenger bag into a juice box? do you have any idea how hard that would be to clean???&quot; ;)<br />
everything about this is awesome, even the cello!<br />
They might give you some funny looks at airport security if you sent this thing through the xray... but great idea.
I thought you were moding a mail bag to hold liquids. huh! (scratching head) i wuz waaaaaaayyyyyyyyy off.
I have a panel that outputs 15.4v at 50ma... would that be overvoltage for this regulator? It's the same dimensions, and I could get a second one to up it to 100ma. I thought that this might help with some of the charging issues, as the panel will not get up to 7.4 volts unless its in perfect conditions, while a 15.4 volt panel will get up there rather easily. Any ideas? If this isn't a good regulator for this, is there a 1A regulator that would do the same thing? I am looking to build this into the lid of my cross-country backpack, with some really solid waterproofing. Awesome Instructable!
where did you get the 15.4v panel?
15.4V should be okay for a 78M05. Maximum input voltage is around 20..25V, depending on the manufacturer, check data sheet. But 10.4V will be regulated away (i.e. lost as heat). So you will get only 33% of the input power on the output. The 7.4V/100mA panel is the better option, as only 2.4V will be lost, so you will get around 60% efficiency. On the other hand, 2.4V difference might be not enough. You might have to look for a Low-Drop-Regulator. The 7805 is kind of the working horse for voltage regulation, although not always a good choice when efficiency is the prime issue. Sorry, I have no part numbers available, just check some data sheets. For best efficiency (though you probably won't get much better than 90% if at all), you might want to use a switching voltage regulator. But these normally doesn't come as a single part.
This Link is to a schematic of this exact circuit, but with the addition of 4 Rechargeable AA batteries. I'm fairly confident it would work, any thoughts?<br/><a rel="nofollow" href="http://i305.photobucket.com/albums/nn202/derektmartin/Batteryphotusb.jpg">http://i305.photobucket.com/albums/nn202/derektmartin/Batteryphotusb.jpg</a><br/>
could you make it simpler im only 13 and geting into electronics and soldering
what's a "project box"?
i'm sorry I can't stop laughing because your question matches your profile picture right now. A project box is a little black box that has a screw-on lid that you put your electronics projects in. You can get them at radioshack or the source or really cheap online.
ohhhhh, ok. thank you........ im so dumb..
ok I didn't mean too insult you or anything, I was just telling what a project box was...
and thank you for telling me what it is.
Is it possible to trickle charge a notebook with solar panel (or is this more for charging small electronic devices)? Something else would probably have to be done because I don't think you can charge a laptop by usb, unless the panel charged an inverter (I think there are a few usb chargeable laptop batteries/inverters). Is there any other way this can be done (such as components that would allow the laptop battery to be trickle charged directly from the panel?
thanks .
it is "0.47UF 50V electrolytic Capacitor Jameco #610589" 0.47mF 50V Electrolytic Capacitor is a HUGE capacitor the size of a little car standing up.
Great Instructable! I am very keen to start this project myself. I have been looking at some commercial solar bags, like Noon's, which incorporates a small battery into the solar panel wiring. Would this be hard to do? Would it allow the same size solar panel to charge larger electronics? another instructable? :) thanks heaps
hay are you able to put the unused electricty into a battery if it is not in use so you can use the power for latterz
:( i wanted it to be drinkey juce not cpu juce :(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(:(
This is an excellent instructable. I am however very new to working with electronics. Can anyone explain why we need these specific capacitors? Can they be substituted with something else to incorporate a larger solar panel (Like one with a higher volt rating or a higher mA rating)? Thanks for helping the newbie.
You don't need those specific ones. The point of them is to "smooth" the current/voltage. They can be any value or type, but I would stay away from polarized caps (ones that have a positive side and a negative side). Finally, the size of the solar cell does not change the value of the caps. You could easily use a bigger panel with the same caps.
This instructable takes longer than it seems!!!!!!!! Mebbe some1 could make a clearer one?
hope you can add a video step by step instructables :)
the solar panel is available cheaper at these places:<br/><br/><a rel="nofollow" href="http://scientificsonline.com/product.asp?pn=3026810&mr:trackingCode=84C1EB55-C803-DC11-8462-001422107090&mr:referralID=NA&bhcd2=1179434921">edmonds</a><br/><br/>and here:<br/><br/><a rel="nofollow" href="http://www.outsidesupply.com/index.asp?PageAction=VIEWPROD&ProdID=87">outside supply</a><br/>
Do you have any idea what the charging time for any of the tested devices is? Or how many mA it puts out?
It uses a 5V 500mA voltage regulator which is USB standard for output as well.
But that's just 500mA max, right? I didn't do too well in circuits class... I was wondering what it usually puts out w/ average sunlight, if that's different from 500mA.
Yeah it's output current is 500mA (or slightly greater) and according to the spec sheet as long as the input/output voltage differential is greater than 2v you should be getting the full 500mA +. So with the solar panel rated a 7.2v you should be set.
The large cap is just to ensure a more constant power for the regulator to do it's job. That's why substitutions are ok. A large variety of capacitors will work fine in this situation.<br/><br/><a rel="nofollow" href="http://www.southwest.com.au/~jfuller/electronics/regulators.htm">http://www.southwest.com.au/~jfuller/electronics/regulators.htm</a><br/>

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