Energizer USB Battery Charger




About: I like to take things apart, sometimes they go back together sometimes they end up as something entirely different then where they started.

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?

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Step 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.

Step 2: Prep the Circuit

Here is the circuit in all of its' glory. Pretty small and I am guessing similar to the minty boost circuit as it takes the available 3v from the batteries ( 1.5x 2AA ) and up converts it to 5v

Since we don't want to use the silly phono style jack we are going to desolder it from the board. This is fairly simple and easier if you have desoldering braid. If not then heating up one pin till the solder melts then rocking it out with some pliers and repeating for each of the three pins should inch its' way out of the pcb.

Use a multimeter or your eyes to figure out which connection is positive and which is negative. It will be important later when we wire it back up. It can be found easily by looking for which solder connection is grounded, which isnt used, and the remaining one is the power.

Step 3: Prep Your USB Cable

Now that you know where to solder the power and ground connections you need to prep your USB extension cable.

All we care about is the female end as we want to plug other devices into it. In the picture I have cut off all but 3-4" of cable leaving the female end.

Use your wire strippers or a knife to remove the plastic wire shielding almost all the way up to the USB connector.

Open and seperate the wires out. Inside you will typically find, Shielding, ground wires, and 4 insulated wires in standard USB colors Red(+) Black(-) and white+green for USB data

We only care about the red and black wires as we are only using the port for power so we can loose everything else.

In the second picture you can see the shielding cut away and the green and white wires shortened and bent back out of the way and away from each other to not short out.

Then some heat shrink tubing (or electrical tape etc) is added to make everything look nice and keep wires from moving around too much.


Step 4: Solder

OK good you made it so far and did not solder the nice looking USB cable you made to the circuit yet. That is because we need to fit the cable through the end cap first!

You will need to play around with the fit a little to get the length of the wires just right so they do not bend too much and everything is snug.

This is a pretty simple solder job but I would recommend some kind of "helping hands" to hold the circuit for you as you go due to not being able to set it down on a flat surface.

Once you are done the circuit board should snap back in place ( it only fits one way) and you can reassemble the charger.

Pop in the batteries and plug in your ipod/cellphone etc and try it out. Sure you can test it out first with a multimeter if you have one but its simple enough that it should just work. A charge light/indicator should come on your device and the blue led's on the top cap's sides should blink indicating it is charging.

This is a great little charger to have in your bag/car for the times that your cell/ipod dies and you are not near an outlet. It also comes with nice Lithium batteries. I have tested it with the iPod nano and my motorola Q and it works great. It does not work on my new iPhone 3G I am guessing this is due to higher amperage requirements by the new iPhone.

Motorola has a resistor in the tips of the Mini-USB cable ends for all phones they make that have a mini-usb port charger. By cutting off this special mini-USB tip infused with the special "I-am-a-legit-motorola-charger" resistor and splicing it with a standard Male USB connector (perhaps the other end of the USB cable you just cut up ;-) you can create a custom motorola USB charger which will work on any USB port and your new USB charger. The included mini-USB charging tip that came with this charger did not have the resistor and therefore did not work.

Also, remember not to set your hand down on your soldering iron like I did. It will hurt and it will take about 3 months to heal.

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    44 Discussions


    5 years ago on Introduction

    When these were available in the stores, it was hard to get different adapters without buying another whole unit. Therefore, I really appreciate how this Instructable turns the Energi-to-Go into a universal charger.

    These still turn up occasionally in the original packaging at Goodwill.


    10 years ago on Introduction

    A local store has stacks of these Energizer mobile chargers for £1.99 each so I grabbed one, neat device except it doesn't quite like being used with rechargable AAs, it'll only charge your mobile/mp3 etc. if the rechargable batteries are freshly charged, once they get too low a voltage it refuses to output any voltage. I have managed to power my Archos AV500 with one for 50 minuites though using freshly charged AAs. I also looked up the specs of the DC boost chip they use, it's designed to work with pure 3v input and has little tolerance for over/under voltage so I haven't tried hooking up 3x rechargable AAs to it yet in case I fry it. One day I'll get bored and say what the flip & see what input voltage it can actually take.

    5 replies

    Reply 8 years ago on Introduction

    Thanks so much for that explanation. I had alway wondered why, when I start charging my phone with it, if I accidentally disconnect, it will not finish off the battery. I came across this article while I was looking for a way to use D-cells or rechargable AA batteries to power my phone since the battery is shot but I don't want to pay for an exact replacement. I am one of those rare people that does not care to have a flimsy credit card sized phone and would actually prefer a heavier, more rugged phone. In any case, I realize now that I will not be able to use this DC boost chip for that. My next search will be for a wind-up dynamo. :-)


    Reply 10 years ago on Introduction

    Yes, thats also the case with the Duracell My Pocket Charger... its sucks... Running 3 rechargeable AA batteries does kill the unit, i tried it myself. The batteries were sitting there for a few days after charging, so there was some discharge. I didnt bother to test it. I was going to try out the Sanyo Eneloop Batteries, because those have low discharge maybe it may work better. But I never seen them in stores and havent got the chance to order one yet.


    Reply 9 years ago on Introduction

    It's been a year and a half just about but I have been experimenting with using three AA NIMH rechargeable batteries attached to the boost chip from the Energizer Energi to Go pack.

    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!!!


    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!!!


    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!!!)



    Reply 10 years ago on Introduction

    Hm. Sounds like crossing one of these with the Joule Thief, to let it run the batteries all the way down, might be worth considering.


    9 years ago on Step 4

    im pretty sure a usb is limited on a computer to about 2 or 3 amps, so a strong Ni-Mh AA battery should work, or else how could you charge the Iphone? Cuz i got 2.5 amp AA batteries around.

    2 replies

    Reply 9 years ago on Step 4

    you need to connect the data lines (green and white) and your iphone will think it is a charger


    9 years ago on Introduction

    I burn myself all the time and brag to people, "I am such a man. I got burnt and i survive!". Lol not really but i get burnt a lot/.

    1 reply

    9 years ago on Introduction

    I have a much easier way... go to ebay, look up: portable usb charger AA. and buy it and mod it to any way you want... you can find one for $5, i love to mod stuff but there is a cheaper way...


    9 years ago on Introduction

    Nice! I bought several of these on clearance from Target any others for under 5 bucks just for the energizer lithium batteries they included.


    10 years ago on Step 4

    i do that all the time i always burn myself with the soldering gun.


    10 years ago on Introduction

    where can you buy one of those energizer chargers, I have searched all over for one and can't find it.

    3 replies

    10 years ago on Step 2

    if the circuit board inside of the energizer is similar to a minty boost, would it be possible to use it in place of one for the solar powered iPod charger. (https://www.instructables.com/id/How-to-make-a-solar-iPodiPhone-charger-aka-Might/)