Inductive Charging For The HTC Evo

[Danny] added wireless charging to his HTC Evo. The hard work was already done for him by Palm, it was just a matter of adding that hardware to his phone. A Touchstone induction charging kit for the Palm Pre will cost you just over $40 for the base station and a replacement back cover. [Danny’s] method removes the induction coil from that cover a relocates inside the case of the Evo. He routes two wires around the battery and solders them to positive and ground connections on the board. Once it’s back together the device draws power without any wires.

[Thanks Matt]

30 thoughts on “Inductive Charging For The HTC Evo

  1. I’m still a bit perplexed by inductive charging. I feel like creating these large EM fields *must* have the potential to screw up the electronics, right? At the very least, won’t HDD’s get corrupted?

  2. I don’t know really…
    wireless maybe but you still have to place the device on a base… that has a power cord.
    Sounds pretty useless for the moment.

    I’m going to stick to my usb wire for now.

  3. I have to plug in 4 devices every night for charging. Blackberry for work, backup cell phone, bluetooth headset and laptop and I personally woul love to just throw all 3 on a mat and charge them at once. But I’m too cheap right now.

  4. I’d like to see some instructions for a super cheap inductive (resonant hopefully?) charging system. I bought a 555 and some magnet wire and was hoping to do it with that, but it’s starting to seem like I’d need some more equipment and more importantly, more knowledge. The plans I have seen are either expensive, or not really well thought out. I’m working on a project where the form factor shouldn’t have a plug for direct charging.

    Has anyone seen a well-done project that uses minimal parts and a cheap oscillator such as the 555?

  5. I don’t understand this fad with wireless power technology. Sure it would be great to just throw all your portables and on a large mat, but are we really getting too lazy to just plug them in? I’d have no problem with wireless power transfer if it were 90%+ efficient, but it is nowhere close, and at this rate everything from iPods to laptops, to cars (google it) are going to wireless charging. With all those inefficient devices, we might as well just scrap CFL’s and LED’s and go back to incandescent light bulbs. :/

    Just my two cents.

    – amishx64

  6. @amishx64
    why resort to insults such as calling people “lazy”

    why do people use washing machines instead of doing laundry by hand?
    why are computers used for calculations instead of slide rules?
    why do cars have starter motors instead of cranks in the front?

    it’s called progress :)

    most mobile devices these days use standard mini usb plugs for chargin (i believe there was actually a law passed about this)
    a universal 5v charging mat would definitely be more efficient than a collection of individual 5v wall-warts.

  7. I think you are taking me the wrong way. I appreciate this hack and have plans for building one of these myself. Lazy as is unwilling to put in the effort ** to plug in your phone at the cost of energy being wasted**

    You could also get one bigger wall wart ans splice it into multiple plugs.

  8. “why do people use washing machines instead of doing laundry by hand?
    why are computers used for calculations instead of slide rules?
    why do cars have starter motors instead of cranks in the front?”

    The difference between using a washing machine and washing by hand?

    The difference between using a computer and using a slide ruler?

    The difference in functionality between a car with a starter motor and a car with a hand crank?

    The difference between plugging some wire and not plugging it in a device to charge it (when it still has to be in the same place)?
    Tiny tiny difference.

    Yes, I’m calling people lazy over this. And +1 to using a single big USB charger for all devices, USB charging needs to be standard on more things than just cellphones and similar.

  9. Although I don’t think these “wireless” chargers would impress Tesla much, having a small mat on your desk is a lot more attractive than a loose micro-USB cable, especially in an office setting. It’s convenient and fashionable, and those two factors have always played a strong role in determining popular technologies. Money will pour in and they will only get better.

  10. I think the ultimate goal with wireless charging is having a single station to charge all of your devices without worrying about what plug fits what. This hack doesn’t accomplish that, but I don’t imagine it that hard to make the induction coils yourself to make your own system. The hard part to create is the charging station that emits the energy to a sufficient distance without being wasteful. This “technology” has been shown powering an lcd tv through dry wall. It might be nice having emitters through out your home for constant wireless charging/powering of everything.

  11. And it is not f*cking wireless. It is just a local magnetic field you have to put your phone in. All circuits wil absorp the field and heat up and a lot of the power to create the field is wasted.

    Those that go on about bein able to charge all your devices just like that don’t get this is a dumb solution. Look into integrated solar cells or get a life.

    1. lolololol

      So maybe this inductive charger has a low Q factor
      but resonant inductive charging is only going to induce a current into circuits that have the same impedance. So that is nice. Not everything has direct sunlight so courses for horses must be observed.

  12. It’s not about laziness, it’s about ENGINEERING.

    If you aren’t plugging something in to charge it, then you aren’t putting wear on connectors.

    When I worked in retail I saw many a sad face behind an upheld hand.
    -in that hand was always a phone with a broken charging connector.

    “Laziness?” you REALY think that’s the motivation for having inductive charging?


  13. Someone phone Tesla’s relatives and let them know how lazy he was for not wanting to run wires and plug them in.

    Lazy, lazy man, all lazy with his lazy self, doin lazy stuff outta laziness.


  14. It’s the wasted energy that bothers me most about this sort of thing, especially as it’s for a relatively minor improvement. As for the problem of having different connectors and chargers for different devices, that is being addressed by switching to using USB as a standard charging interface (MicroUSB is being adopted as the standard phone charging socket in the EU, certainly).

    @NatureTM: For all your cheap hacking needs, see Afrotech –

  15. “Someone phone Tesla’s relatives and let them know how lazy he was for not wanting to run wires and plug them in.”

    Tesla was RESEARCHING better ways of doing it, not trying to put what he already had into every single lightbulb produced.

    ““Laziness?” you REALY think that’s the motivation for having inductive charging?”

    In a lot of cases, yes. In some cases, of course, there are valid reasons to do it, for example with electric cars there’s safety which is much a concern at those powers.

    “When I worked in retail I saw many a sad face behind an upheld hand.
    -in that hand was always a phone with a broken charging connector.”

    I’ve never seen a broken power connector, and I repair broken cables VERY often from people who keeps yanking them from their laptops and stuff, so I think it’s safe to say it’s their fault for handling their devices without proper care. People needs to learn how to handle their stuff – you don’t throw around something that’s made of glass.
    Next we should try getting rid of displays on gadgets, because some people keeps breaking them.

    “it’s about ENGINEERING”
    Bad efficiency = bad engineering. Why don’t you engineer a better connector, if connector wear/tear is the problem.

  16. I’m surprised this is such a divisive hack.

    Sure this is less efficient than other methods, but it’s also a step in an interesting direction for consumer technology. I hope lots of people buy these new devices so more money goes into R&D. I’m sure we’d all like to someday see cheap, efficient, and safe wireless energy transfer. I would love to have my cell phone charge automatically and to not have to worry about how many outlets I have near my home theater.
    I know that there has already been a much work done in the field, but consumer interest is an excellent driver.

  17. “why resort to insults such as calling people “lazy””

    I’m even proud that I’m lazy because this laziness is the ultimate motivation for lots of ideas regarding more efficient work etc. In fact, humans tend to automate things just because of that.

    Regarding the article: I’m more into good ole’ connectors. I trust them more, though *only* if they are reliable enough. Typical audio-like connectors (TS/TRS and those with a hole) are of that kind and their only problem was too much flavors of them. Even worse, somehow all my earlier phones (despite different manufacturers) had those crappy connectors with one row of contacts and a couple of hooks – and that’s for charging, too. It seems that EU is making mini-USB mandatory for phones; this is fairly good news in comparison. On the other hand, an universal charging mat could simply change the frequency, or even switch parts of the coil, to match the receiving end better.

  18. You people are way too sensitive about the word lazy. Though I have to admit that I am one lazy bastard. Being lazy has motivated me to automate and simplify a lot of the processes in my life.

    With that said I agree that using an inductive charging pad is a waste of energy. The myGrid has similar functionality without having to create a field to induce current, but I wouldn’t use anything that requires me to use a special case or attachment. I’m too lazy to deal with such an inelegant solution. If there were a standard, manufactures could easily and cheaply build contacts into the back of devices.

    And the adapter dongles are just lame.

  19. I just want to reiterate the point about broken connectors — it may not be true of everybody, but I’ve lost two PDAs, an MP3 player, and two laptops, all to broken power connectors, all in the past decade. The laptops I was able to repair myself, the MP3 player was badly outdated anyway, but the PDAs (closest thing to a smartphone…) had proprietary, fiddly connectors that I just did not have the means to fix, and a professional repair cost half as much as a new device. I don’t know if “wireless” charging is really /there/ yet, but I for one can see a really good reason for it.

  20. This sounds like a great solution. One month into my EVO and the USB power connector is broken. I have to twist the cord in all kinds of ways and cross my fingers it’ll make contact to charge. Apparently others are having the same issue and Sprint/HTC want $100 for the insurance deductible first. My friend says it happened on his other phone way back when too. Soldering must have become loose on the circuit board.

  21. Add me to the same list…my micro-USB port broke
    after two weeks, and ALL I ever used was the
    supplied USB cord that came with the phone, which
    is as heavy and thick as a hot water hose
    on a washing machine.
    Sorry HTC but micro-USB is NOT the way to
    go for something that gets this much use.
    You should have gone with mini-USB at the
    very least. The size difference is minimal
    but the durability difference is huge.
    I was happy with the phone but now I am

  22. Same deal, looking into this mob because my charging port broke sprint wants 100 bolas and htc said you’re paying for it if it’s physical damage.

    Endgadget had article about this phone doing this back in last august, however; everyone that sells this phone has never heard of this happen ever.

    It’s funny how companies dont even have to honor their warranties anymore.

  23. You know, for all the plugs that people plug in, and LEAVE plugged in, and all the manufacturing resources that go into making all of those plugs…

    What if your charging pad operated in a micro-power state when not in use. Only the tiniest of trickle, utilized for monitoring for the presence of devices. If a device is placed on the pad, a small magnet in the device could trigger the pad to power up and start an inductive coil in the area of the pad nearest the activated region. When the device is charged, the unit powers down, and occasionally comes back up to trickle charge the unit for a short burst every now and then. Using high efficiency monitoring circuitry, I think that whatever inefficiencies may exist in the inductive charging process, could easily be offset by power savings found when the pad is not in use and shuts down. There is also the savings of not needing half a dozen wall warts to be manufactured, and a new one with every new device.

    The inefficiency complaints really only can be counted against dumb devices. Smart devices are where it’s at. Power as required, when required, and never more than needed.

    The other argument is that one can’t ever forget to plug in their phone or iPod if they need only set it down each night. A busy office drone can set the phone down and pick it up and run without fumbling over which wires go where. There is of course, the aesthetic as well.

    I’ll bet that a well designed smart inductive charger can be made to waste less power with controlled inactivity, than wall warts left plugged in perpetually.

    Lastly, I’m amazed that some people here try to dismiss the durability issue, simply because they’ve never seen a broken connector. Just because you’ve never seen the problem doesn’t discredit the validity of the claims of the many who have seen it. A small connector, frequently used, WILL EVENTUALLY FAIL.

    Good engineering designs for all the possibilities that a wide variety of consumer can throw at the product. Poor engineering expects all users to adapt to it’s demands. Remember DOS. It was an amazingly efficient OS that took very little memory… but it was also quite limited, and required users to learn extensive lists of commands and modifiers. GUIs took it’s place and the world hasn’t looked back. GUIs are an example of engineering adapting to the user. Trying to get the whole world to “be careful” plugging and unplugging their phone cords, and asking them to unplug wall warts when not in use is simply not going to work. Some will get it, and do it. Some simply won’t care, and will just replace the cord when it goes bad. Others won’t even understand why it’s an issue… God, I’ve meet people like that. There is NO HOPE of changing those types. Rather than let them keep wasting resources with damaged product and a dozen wall warts persistently and constantly sucking juice, why not design the smart inductive pad that knows how to shut off, knows how to manage power draw, and eliminates a point of breakage, therefore reducing the amount of wasteful manufacturing of and endless stream of wall warts.

    Criticism of this technology does us no good. All our technologies had to take baby steps, and someday inductive charging will mature.


  24. “The inefficiency complaints really only can be counted against dumb devices. Smart devices are where it’s at. Power as required, when required, and never more than needed.”

    Unfortunatley the inefficency is in the power transfer also not just wether a device is present or not, as for the technology maturing remeber it can only mature to the point that physics and thermodynamics allow.

    Inductive charging is nothing new ,, why its such a buzz topic of late I dont know ,, its been around for many many decades. The principle is basically a simple coreless transformer they use it in electric tooth brushes.

    Ok the loops are tuned better and can be retuned on the fly but the base tech has never changed.

    Not to detract from its handyness ,it’s a nice feature just a bit greedy on energy because of its higher lossy nature.

    I have used it many times.
    When you need a fully watertight system for example inductive charging is ideal , as is indcutively coupled communications (just like RFID) you can literally pot your entire system in solid epoxy resin as long as you never need to get it back out :D

  25. Why not include a power switch on the mat or stone or whatever other device that is used to produce the EM field. If your device isn’t on the charging apparatus, then flip the small switch to the off position thus saving the “wasted electricity”. Seems like a simple solution to me. Interesting concept….yes. Useful technology….yes. Necessary accessory….not so much. But then again that’s why its called an accessory, its not necessary. Added at the users discretion.

  26. I guess people forget why they are on this site. For mods and hacks. I do believe that is what this is. Enjoy and appreciate it or get over it. I know I am. Thanks for the post Mike. I will be giving it a go!

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