Instructables
Picture of Lithium Battery Solar USB/ iPhone/ Arduino Charger
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One of the most fun and useful projects on instructables is to create your very own solar USB/ iPhone charger. They're not overly difficult to make, nor are the parts overly expensive or hard to find. For the most part they do a rather good job of charging up small gadgets. Mostly.

The big flaw in the DIY solar charger world are the batteries. Nearly all the designs on instructables (including all of my designs) use standard NiMh rechargeable batteries. They're cheap, easy to find, and very safe to use. The problem is that their capacity and voltage are both low, and the gadgets we keep wanting to charge are getting bigger and better batteries.

For instance an iPhone 4 has a 2,000mAh battery inside of it. Now that isn't too tough to charge up decently with a well made solar charger using 2 or 4 AA batteries. On the other hand an iPad 2 has a 6,000mAh battery pack on it. Not so easy to charge up.

The solution for these problems is to ditch NiMh batteries and turn to Lithium batteries.

In this guide I will show you how to make your very own Lithium battery charger. One that is cheap to make, easy to build, and most importantly safe to use.

(Oh and help me win the Instructables Green Tech Contest by voting for this project! An iPad would be great for my classroom! Even better, I'll build a massive Lithium powered charger to run the iPad. It'll be 100% green in my classroom.)

 
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kamhagh1 month ago

how can i charge & use the lipo to charge my phone at same time? (solar charging Lipo -> lipo charging phone -> )? at same time while walking :) (panel installed on my bag or something, or cars front window)

kamhagh1 month ago

how can i charge & use the lipo to charge my phone at same time? (solar charging Lipo -> lipo charging phone -> )? at same time while walking :) (panel installed on my bag or something, or cars front window)

avelyn942 months ago

what if i wanted to put 2 output port how should i connect it?

colbtron2 months ago

Adafruit has some sweet Li-Poly batteries which work well. What I'd like is to be able to add a LED strip to show how charged the battery is.

gluvit2 months ago
Great project
Mr_Rep3 months ago

rather than the DC-DC USB Boosting Circuit could i just use the guts from a cigarette lighter usb charger? since it contains the 5V regulator

Mr_Rep3 months ago

rather than using the DC-DC USB Boosting Circuit, could i just use the 5V regulator from a cheap cigarette lighter usb charger?

Mr_Rep3 months ago

sssoooo.... wheres the lithium kit from the video on the website? all i see is this massive and expensive unit that has dual charging ports. where can i buy a kit that uses a simple Li-ion battery, and one usb connection fairly cheaply?

jjjacala4 months ago

where i can get a free battery charger contorler?

jdw1001 made it!5 months ago

I made this neat little charger but I need a little help. It works fine with my old Ipod but it won't charge my Iphone 5. I bought the booster from BrownDogGadgets and modified it by taking out the battery contacts. ( I may have bought the wrong booster) I am working on making another one. But anyhow I found that this circuit would charge my Iphone 5 as long as I had the circuit in line with my car battery as it charged the Lithium Battery and my phone. That tells me that everything is all right. I just need more power or current flowing. I am considering adding another battery to the circuit. Any advise is greatly appreciated.

Thanks,

Jeff

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Just wondering because I can't seem to find this directly answered anywhere. Is it ok to be charging up your batteries via usb or solar while using them to power whatever you have plugged into them?
Nothing bad will happen if you do both at the same time. It's not going to harm the battery.

Your'e just sucking power away before it even hits the battery.

Will this then confuse the charge controller?

Is it thus necessary to use another type if charger? Like this one: http://www.adafruit.com/products/259

callega11 months ago

Thanks for this great project! I'm going to try it!

I have two questions:

1. There is a problem if you have connect the USB input and the solar panel at the same time?

2. It's possible to have connected any input source and charging a device at the same time?

Thanks again

1. I believe it is no problem as long as you protect your solar panel with a diode. However, the solar panel would only be able to contribute any power if the voltage is higher than the input USB power of 5V. Onto this the threshold voltage of the diode needs to be added too.

2. That is a good question. I found a forum post where the different possible szenarios for this setting are described: http://www.societyofrobots.com/robotforum/index.ph...

Moreover, there are special charge controllers which can connect batteries AND load together with a power source for charging: http://www.adafruit.com/products/259

Unfortunately, I haven't found any cheaper alternatives. Therefore I have a question too:

Is it possible to build such a thing as DIY so that it also works for higher charge currents?

I found a cheaper way to get the items needed. I got a 12,000mAH battery and a lithium charge controller/3 to 5 volt Booster circuit and a case for $18 on Rakuten and I also got a 6 volt 320mA Solar panel on Ebay for $8.

lifeinbeats7 months ago

Hi there, not sure if you're responding to comments, but I am trying to reuse an old iphone 4 battery for this project, and the contacts are very confusing! I was wondering if you had any experience with this? Mr Google couldn't help me out this time...

JoshuaZimmerman (author)  lifeinbeats7 months ago

Not a good idea. I sent you an email about it.

pcrotts made it!7 months ago

Super fun to make. I got too big of a switch, but all is well. I taped two old phone batteries (1000 mA each) together for power.

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Cats Science Club made it!8 months ago

Joshua does an amazing job explaining everything he does. Thanks to him we found a love for instructables. Take a look at what we made with a great instructable showing us how.

THANKS JOSHUA!

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Cats Science Club,

Can I ask how you added the On/Off switch to your. What did you wire it to/from? Thank you.

Thanks for noticing the slight change! We have the positive from the lithium charge controller going to the switch and then to the positive on the usb port. In our picture the usb is covered with hot glue. We added the switch because the small red usb light being on all the time was draining the battery slowly. I believe Josh Zimmerman sells one with out a light or shows how to take it off the one he sells. Let us know if that helped and check out our site at catsscience.com!

taylorjr9 months ago

Thank you for the detailed project. I've zero interest or knowledge of electronics prior to finding this site, now i'm stoked about building this and I have all the pieces to make my first project...at least I think so, we'll see. Thanks again for peaking my interest in something I think I can really use and will benefit me to have.

But please help, Can I use double AA batteries with the lithium charging board, if I use 3 aa batteries i'll be at 4.5V, shouldn't that work? I already own many rechargeable AA's and zero lithium batteries.

My reason in wanting to try this is for the lighting indications. I'll know when fully charged and they wont be over charged, etc.

Again THANKS!

I followed your project but I am having a problem with the phone battery not charging even with phone off. I wired this as to the specs and double checked....Do I need to put another blocking diode to the USB controller?

By the way, I like this solar charger.
We have used usb circuits that worked find for everything but Apple products. Could it be your usb circuit? Like it was for us. Is the battery on the charger fully charged to start with? Good luck!
"In this guide I'm using a 5.5V 320mA solar cell which is encased in a hard plastic. Any large solar cell will do, but ideally for the Charge Controller you want your solar cell between 5-6V in power."

What if my 6.3V solar cell only has 30mAh. Will that still work?

Anyone with knowledge, feel free to answer.
bobert6101 year ago
The small black component that runs length wise along one side of the lithium charging board popped off and i lost it. Its the one that is directly in line with the negative inputs and reads "322" if i am correct....i bridged over the two spots with solder and it still charged the battery...does it need this component to function properly?
miszcz_tcz1 year ago
Can this circuit charge AA batteries as well? Can add switch that will cut off Lithium charging circuit, and than AA bateeries will be charged directly from solar cell/boosting circuit?
LazerPaul1 year ago
Hi, I recently saw your tutorials on solar usb chargers. They seem pretty straightforward and cool. I'd really like to get into it. I just had a quick question.
Is it a bad idea to not have a battery in the solar charger? Essentially just the solar panel, no case, no batteries, just plug and charger.

I'd be mainly using the charger when I go camping.

Thanks for the help!
Schmidty161 year ago
How much is this if i bought everything from scratch
Schmidty161 year ago
How much is this if i bought everything from scratch
Hi and thank you for this great tutorial, being a newbie in the electrical world I truly appreciate this. I have a few questions:
1) Can i make this charger for anything else than an iphone i.e. a cheap cellphone which I use only for texting? (can i use the same materials)
2) I bought the "single USB boost + controller " from your website instead of the 2 of them separate and i was wondering How i should solder the panel mount and lithium battery since there seem to be only 2 soldering hole on the board.
3)finally, how efficient do you think this charger would be if im using a 6v/ 50 mA solar and a 3.7V/110mAh (tiny) lithium battery. (i.e. How long would it take to charge the phone,and how long would it the charge last me for.)
Im sorry for such a long question, but i would really appreciate your help. THANK YOU AGAIN :)
built one very similar. using a 4000ma battery. experiencing phone battery draining when plugged in, even when phone is off. what type of blocking diode should i use that has the least resistance
thanks for the tutorial. I do have several questions. I appreciate any knowledge provided!

I made my charger very similar to this, Im using a 4000ma 14.8wh LIPO
I am using 2 6v 250ma and one 5.5v 320ma solar cells. Can i wire these in parallel to get an ending amperage of 820ma? I know the voltages don't exactly match up, but its close.

my real issue is that my charging circuit wont add power to my phone (android rezound) . I have tried turning it off when i charge and letting it sit for a long time. The charge light on the charge controller and my phone light up acknowledging that it is charging but when i check my phone's battery is lower than when i started. I am using a 1n4001 diode on both the solar input and the usb output to prevent back charging. am i doing this wrong?

i have been charging the lipo from micro usb
ill attach photos for help.
NightLord1 year ago
Could we replace charge controller with simple voltage regulator set to upper charging voltage 4.2V, which would prevent current flow in battery after it is fully charged?
Or is that approach simply too naive? :)
Seafarer1 year ago
I have a 2.1mm female plug. If I solder it with negative to the left and pos in the middle it wont work (negative voltage on the multimeter). Switching sides gives me a positive voltage (normal) on the multimeter and it works...
Seafarer1 year ago
Newb question - I have a 8V 310ma panel, is it ok to hook it up to this charge controller - https://www.sparkfun.com/products/11231? It says 5v input charge... Thx!
Eristeel1 year ago
or ideal size of battery for an altoids tins*?
Eristeel1 year ago
Is the tin box used in this project the same size as an altoids tin?
also what size is the lithium battery..well what would be the most appropriate size?
MyTopFan2 years ago
Does this possibly work with the iPhone 5?
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