A simple modification will allow you to use a $20 AA Energizer cell phone charger with any USB device to charge your cell phone, iPod etc. *(note in testing it does not have enough juice to charge an iPhone 3G)
It cost about the same as the minty boost ($20) and is about the same size. Almost no assembly is required by compairson. I completed this project with parts I had lying around. Not sold yet? Did I mention it has flashing blue LED's?
It cost about the same as the minty boost ($20) and is about the same size. Almost no assembly is required by compairson. I completed this project with parts I had lying around. Not sold yet? Did I mention it has flashing blue LED's?
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Signing UpStep 1: Parts
Here are some of the parts and tools you will need.
- The energizer AA battery charger for cell phones (found at many drug stores)
- USB extension cable ( Comes with many different USB devices/dongles, you or your friends probably have some in a drawer somewhere)
- Soldering Iron and Solder ( I like the radio shack butane powered ones because they heat up fast and have no power cable to catch on things, also highly portable)
- Wire strippers ( these came from the dollar store and they are 3+ years old! )
Disassemble the usb charger. It is pretty strait forward. The cap with the springs pops off easily to remove the batteries. The remaining cap can be pried off with a screw driver or by pulling the two halves of the casing apart. What we want is to get at the circuit inside the cap.
- The energizer AA battery charger for cell phones (found at many drug stores)
- USB extension cable ( Comes with many different USB devices/dongles, you or your friends probably have some in a drawer somewhere)
- Soldering Iron and Solder ( I like the radio shack butane powered ones because they heat up fast and have no power cable to catch on things, also highly portable)
- Wire strippers ( these came from the dollar store and they are 3+ years old! )
Disassemble the usb charger. It is pretty strait forward. The cap with the springs pops off easily to remove the batteries. The remaining cap can be pried off with a screw driver or by pulling the two halves of the casing apart. What we want is to get at the circuit inside the cap.
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The boost chip from this pack is set to operate in a voltage range from the low of 2.7 volts to the high of 3.6 volts, although it will only utilize 3 volts on the input. It is designed to work specifically with Disposable Lithium batteries, which start with a battery post voltage of 1.8 volts each, then down to 1.5 nominal.
So at first glance, it would seem that three AA Nimh batteries could blow it, as they would run 3.6 volts nominal from the three batteries, and would start with a post voltage of nearly 4.3 volts. But hold on there!!!
The chip that Energizer uses will take a voltage all the way down to .7 volts, or all the way up to 6.5 volts, so three batteries won't blow it, however Energizer programmed the chip to be set specifically for Lithium's, so it won't operate if you try three Lithiums, or four Nimh batteries. That being said, when the three Nimh batteries start out, is shouldn't work... BUT HOLD ON THERE!!!
Now the next part is the fun part. The chip documentation from the manufacturer states that it has over voltage circuitry that gives it an extra 1.44 volts on top of the programmed operating current. Since Energizer set this to operate at 3.0 volts, it will safely operate at 4.44 volts! Divide 4.44 by three and you have 1.48 volts per battery, which is more than the max post voltage of a nimh battery!!!
YEAH!!!
The real big positive here is that three nimh batteries will drain about 94% capacity before they shut off when put into this three battery configuration. That's about four hours of play time.
The chip gives you up to 630 milliamps, which is 130 more than the mintyboost. You can now get the Energy to Go unit shipped from Ebay for under $5 dollars. With any large Altoids tin, a few extra parts (need resistors to set up charging for Ipods, Zunes, etc...) you can have your own boost supply for under $15!!!
Now here is the fun part... connect more than one of these together in parallel, and you increase your current! I have done this, giving me a kit with six batteries and 1.26 Amps of current power! I can power my Kodak Zi8 camera for two and a half hours straight in HD recording without having to worry about running out of power!!!
AWESOME!!!
If you ran three of these in parallel, which I have done, you can charge a Zune or an Ipod in about two hours flat.. and do it three times!!! (but the battery pack weighs more than your head!!!
So there you go! With the Energi to Go, they have such a great intelligent circuit, and you can get them dirt cheap, it is pretty darned easy to put together a cheap alternative to the Mintyboost, and get more life out of it as it uses three batteries instead of two! (plus, if you do it right, you have space left over for actual Altoids in the tin, great if you have terrible death breath!!!)
Ciao!!!