How to make a rechargeable USB battery (solar edition)

GET THE CIRCUIT DIAGRAM HERE:

http://neotoy.tripod.com/archive/2009/youtube/circuit-diagram.pdf

An emergency battery charger for your mobile phone comes in handy, but it's not the ultimate solution; once it's dead it's useless (what a waste). If you want to really get off the metaphorical grid, you can follow the steps in this video to construct a more robust circuit that will not only bail you out of an inconvenient situation but also recharge in between uses. The simple addition of a low voltage solar panel and rechargeable batteries makes this possible. Enjoy!

Parts:

4 x NiMH AAA Batteries
1 x 4 AAA battery holder
1 x Small PV (photovoltaic) solar cell
1 x Diode rated min 5V 500mA
1 x USB cable or cable of your choice

Tools Required:

Soldering Iron
Lead Solder (the kind with flux core is best)
Heavy Shears
Wire strippers
Electrical tape

Tips:

Solder in a well ventilated area on a non flammable surface
ALWAYS WEAR EYE PROTECTION
Check the circuit polarity before final soldering

Category:

Howto & Style

Tags:

• USB
• phone
• charger
• solar
• rechargeable
• battery
• NiMH
• DIY
• PV

[shadowthee]

I like how the diode in the beginning of the video is backwards. Later when he charges the phone it's suddenly in the other way? ... Obvious troll is obvious.

[neotoy]

@shadowthee Turn on your annotations bra...

[unknotmiguel]

what happens when you feed the solar cell, with power? does it releases electrons or radiation in some sort?

[neotoy]

@unknotmiguel An excellent question, unfortunately I don't have an answer. I had just assumed that the solar cell would behave similarly to a resistor - effectively shorting the circuit and draining the charge in the battery pack. I do not however have any experience to support this assumption.

[ledguy315]

With kind regards neotoy, please further your electronics knowledge before making a faulty how-to video. Im an electronics engineer and you have many problems with this circuit and in your terminology. Better luck next time.

[neotoy]

@ledguy315 Prove it.

[neotoy]

@mikedrz No, it's right in the video. The two 9V clips snapped together reverse the polarity. When they are removed later in the video you will notice that the diode has also been moved to reflect the changes. Lastly if you download the schematic you will notice that it is correct. If people aren't observant enough to notice such basic aspects of the design they are probably wasting time no matter what they do. You can send the $100 to neotoy@hotmail.com :)

[anupamvipul233]

r u serious one cell low voltage it wont be able to charge battery only prevent from self discharging (function of Trickle charger)

[jezikime]

what kind of diode did you used?



[SaulGoodwin]

actually with a 6v solar panel in good sun producing 6v, with the forward voltage drop of the diode of say 0.7v for a basic 4001 silicon rectifier diode, you'd get 5.3v out which equates to 1.325v per cell on 4x NiMH cells. The fully charged voltage of modern 'low self discharge' NiMH cells is slightly over 1.4v per cell.. So you'll nearly fully charge 4xAA NiMH off this if you have enough sun. Like to know how much charge this will put in a phone before output voltage drops too low.

[shadowthee]

Further more, like ledguy315 says. You have many faults in your circuit. Please learn more before posting videos on circuits that won't work. Yes, the batteries will charge the phone. But the solar panel won't charge the batteries. It's voltage is way to low. And if you want to charge batteries you also have to have a circuit that controls when to stop charge the batteries to prevent damage to them.

Try again in a few years when you know what you're talking about.

//Shadowthee

[cheatcoadmaster2000]

your diode is backwards

[Crazy1991Rocker]

hello! I want to make a solar battery charger and I found this video.I have a 5.5V 150mAh solar cell and I want to charge a 3.6Li-ion battery.I want to ask you,the diode is an 1N4007? Thx