Evo 4G wireless Induction charging modification.

I was really pretty content with my wireless device. It could do no wrong, did everything i wanted and then some, and was customisable with so many great Roms released at a rate that i for one, definitely could not keep up with.

Then came the HP Touchpad firesale, a world wind of an event that put a relatively unknown device that was given the ax within the reach of many who had before its sale price point of 99$ never had the need or want for a device similar to one of the worlds most overpriced and overhyped devices, the ipad. I’m pretty sure that made Apples marketing division sit up and notice. It was a frenzy fueled by the various deal sites.. servers crashed, babies went hungry and kittens perished as the frenzied masses F5-ed the weekend away. Some were lucky, most were not. HP oversold them selves on a product they themselves didnt think was very good. But heck, for 99$, a 10 inch internet connected touchscreen tablet computer sporting a gorgeous IPS panel capable of browsing the web and then some is a bargain thats simply to good to pass up. The myriad of uses for a device like this for 99$ is only left to the imagination. I too got into the fray and managed to snag one complete with charging dock and keyboard. After a couple of weeks of using it, i can definitely say its $99 well spent. Its not particularly impressive but from Angry birds to email to the web, it gets the job done. What impressed me most wasnt the Touchpad itself though. That, would be the Touchstone charging dock.

The Touchstone charging dock uses a mechanism called Induction charging to get power across from the dock to the Touchpad without wires. Actually, that last sentence to me, deserves an exclamation mark. Thats simply brilliant. Place the Touchpad on the dock and it automatically starts charging. the Touchpad is aware of proximity of the dock and can be set to do a number of different things while charging such as pretend to be a 10 inch photo frame pulling images from its internal memory or facebook. This is genuinely novel innovation that has been largely overlooked if its available in only one, now defunct, tablet of all that are currently available. This wireless charging thing really impressed the heck out of me. I looked into it and found out that HP also had it built into their Palm Pixi and Pre wireless devices… again which many would not have heard of thanks to some of the more popular devices on the market overshadowing them. Yes,  i’ve heard of 3rd party companies coming up with wireless charging solutions but they’ve been less than stellar in working right. Further investigation uncovered that an ingenious chap figured out how to shoe horn the Palm Pixis induction charging unit into the venerable Evo 4g. And that made the bells ring. It was a racket in my head!! I could just imagine having a whole bunch of charging pucks and never have to ever plug in my Evo ever again to charge it. I just had to have it, just so i could free myself from that dastardly charging umbilicus!

Taking my cue from the chap who pulled this off, this is my take on installing a Palm Pixis induction charging unit into an Evo 4g. Be forewarned, I take no responsibility, provide no support, answer no questions beyond whats been written here. The risk is all yours. Now thats been said… heres the single most useful mod one can do to the Evo 4g. Its become indispensable.

What you will need:

  1. – Palm Pixi or Pre back cover, Touchstone charging puck and power supply. Google Palm Pixi Touchstone charging kit.
  2. – Torx t5 screw driver.
  3. – Soldering station with a fine tip, suitable solder, rosin and related accessories. If you dont know what they are, i would suggest reading up and practicing on soldering or to simply give it to some one competent to do it for you. Its a 5 minute job if done right, The wrong tools will only lead to frustration and most probably a damaged device.
  4. – Tools to pry The Evo case open.
  5. – electrical tape.
  6. – 30 awg stranded wire.

Pictures paint a thousand words:

Evo 4G disassembled.

Right then, theres plenty of tutorials on how to dissasemble and void any warranty you may have left on your Evo. You may want to start there, but honestly, this image says it all. Pop the back, remove the battery, remove the micro sd card and use a Torx T5 screw driver to remove the six screws. Warranty, if there was any, becomes void the minute you remove the screw with the tamper proof sticker on in. Pry the two half of the case apart gently. They’re snapped together with latches and dont take much force to separate. I used a DIY pry tool. Dont knock the frog, it works.

Common ground/ Negative. Solder this as flat as possible as it gets sandwiched pretty tight and will casue problems in reassembling the case. Look at the back case and see how they come together to see what i mean.

Use thin wire. 30 awg stranded wire is what i used. Its flexible and thin enough to route through the case without difficulty. Do use an iron with an appropriate tip, i used a Weller ST6 tip. Tin both ends before soldering. That shiny gold pad will fight you if you dont use solder with a rosin core or dont have flux on hand. Solder it down as flat as possible as the case sandwiches the pad and wont fit right during reassembly. Look at the back case to see how they come together to see what i mean.

And here comes the hard part. See that little circular gold pad. Thats where the positive lead needs to go. This pad fought me and took some doing. Be very careful in not damaging the components on either side of it. Practice on something else first if in doubt.  Orient the wire to run to the left before soldering. See the image below to get an idea on where the wires will run. Use a multimeter to confirm continuity before closing everything up. Plug in the Evo charging cable and test the newly soldered leads. Its should show 5v or there abouts if everything was done right.

Replace the rubber boot over the vibration motor once done with the positive lead and use tape to keep the wires down and to provide strain relief. Run the wires out of the back case just next to the battery spring contacts and reassemble the two halves of the case. It exits neatly with 30 awg wire. See picture below on how it exits.

Remove the inductive charging unit from the back of the Palm Pre. Its stuck on with glue. Slide a razor underneath and it will come off neatly.

Stick the charging unit into the back of the Evo 4g. Its an eerily good fit.

Note how the negative and positive leads exit from the Evo 4g. Solder them to the pads of the Induction charging unit. Refer to the image above for polarity. Use some electrical tape to cover the solder joint. and hold the excess wire down to act as a strain relief and put it all back together. Align the cover with the back to see how best to avoid crimping the wire and to provide the least bulge before snapping it shut.

Palm Touchstone charging puck.

Turn the Evo on and place it on the Touchstone charging puck and the red charging led will light up. Magnets in the puck and 4 steel discs in the induction charging unit make it easy to align the two every time. Look Ma.. no wires!!  Charging time is roughly the same as using the cable except infinitely more convenient. 🙂

Every mobile device should have this integrated into it. It just so convenient. Im not going to miss the charging cable except when i need to move huge amounts of data. Life was good with my Evo, now its better.


16 Responses to “Evo 4G wireless Induction charging modification.”
  1. Ben says:

    Will this work with a phone that has a metal back eg leo? probly not I’d think..

  2. Pete says:

    Won’t work with metal 😦

    • asmd says:

      it probably wont in the traditional sense, but it may work if the induction charging unit is placed outside the metal back cover and behind the soft silicone case. I had a HD2 and used it exclusively with the silicone case that came with it.

  3. erwin says:

    would it work with a galaxy s ?

  4. Sam says:

    This… this is pure awesomness!!!!

    Thanks. I may have to find a dead Palm off eBay, JUST for this!!!

  5. fmcfm says:

    Nice. The Palm Pixiu must have shipped with this cover. The newer Palm Pixi Plus doesn’t have it, and it must be purchased separately. It’s available from Amazon for about 7 bucks.

  6. fmcfm says:

    On second look, that seems to be a Palm Pre cover, not a Pixi. This cover shipped standard on the Pre. It’s an option on the Pixi.

    • asmd says:

      You’re right, my mistake. Its the palm pre cover that i got the induction charging unit from.
      Works just fine. 🙂
      Thanks for pointing that out, have amended it to avoid any confusion.

  7. Nathan says:

    Can i do this with the PowerMat for the HTC evo? i kno its a strang question but i do use backup power bricks alot.

  8. steven says:

    Could you please tell me how you determined that was the best place to hook your positive lead? I am trying to do this mod on a few older phones and there are no tutorials that I can find for them. Since they all look very different inside I will probably have to break out a multimeter but I’m not sure what to look for. Any help would be great

    • asmd says:

      Hi, somebody else had already figured that bit out. Using a multimeter and tracing from the microUSB 5V in, look for a spot to solder. It would be very difficult to solder to the microUSB connection itself (simplest solution actually) although i have seen it done with older miniUSB connections.

  9. dan says:

    hi, wondering if anyone could help me out: im about to do this with the palm pixi back for my evo 4g…….. i’m trying to figure out the polarity for the contacts on the pixi coil…….which is contact is the positive and which one is the negative?


    • asmd says:

      Use a multimeter to test for polarity.

      • dan says:

        yes, that is the best way to do it…….i don’t have one handy, but i guess i really should have one by now, just ordered one……..

        thanks for the write up! the phone is really old now so it’ll be nice to do something new with it………

        i want to have it not bulge at all so i’m going to try a few things:

        – paste the coil onto my use my thin phone case and not use the oem back cover
        (case-mate – barely there : http://www.amazon.com/Case-Mate-Barely-There-Case-HTC/dp/B0044YEE1O)

        – keep the back case and see if i can use copper tape in some fashion to minimize thickness

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