Galaxy Nexus inductive charging mod

Fenris_Ulf

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I know this isn't the traditional computer case mod, but modern smartphones are just small, mobile computers and this is a case mod of one, so...

I really like my new Galaxy Nexus, but one of the big problems I had with my original Droid was the micro USB plug had started to wear out after a year and become unreliable. Looking for a solution, I came across a fairly impressive mod on an Evo here:
http://doesitpew.blogspot.com/2011/03/htc-evo-4g-mods-beyond-stock-and-one-of.html
I decided that when I got my Nexus I would try to add an inductive charger. Fast forward to two weeks ago and I had a shiny new Nexus in my hands. First thing was to order the extended battery and cover, a few Palm Touchstones, and a Palm Pixi touchstone cover. The Touchstones were about $8 each and the Pixi cover was $7. I like the extended cover, it feels like a more natural shape for the phone. A big resource was the teardown at Tech Republic which gave me good insight into planning this.
http://www.techrepublic.com/photos/cracking-open-the-samsung-galaxy-nexus/6334013
Based on the internals, it looked nearly impossible to tap into the USB plug - it's just too integrated and there's nothing exposed to tap into. The pogo pins looked like a much better place to tap, but there is no information that I could find about the pinout. Some "experts" claimed they had been disabled in the Verizon version due to the Verizon car dock lacking the corresponding pins. I played a bit with my multimeter and figured out that the two pins closest to the power button are ground. The third pin has about 83K ohms of resistance to ground. Attaching 5v across the pins caused the phone to indicate it was charging, so it looks like it wasn't nerfed by Verizon.

After coming up with a plan, I used a plastic spudger to open up the case as seen in the ifixit teardown:
http://www.ifixit.com/Device/Samsung_Galaxy_Nexus
I peeled the inductive charging circuitry out of the Pixi - it's all on one big sticker, and used a little spray adhesive to stick it on the inside of the extended battery cover. Here's the phone case, internals, and extended battery cover with the Pixi inductive unit installed. The two wires are from an old sacrificial USB cord will be used to connect everything. Sorry for the crappy pics, but all I had available was a six year old cheap camera.
nexusopen.jpg


The only decent place to connect the wires on the pogo pin connector was the top, so I carefully soldered them on. There isn't enough space to run them over the pins so one goes off to the side.
wireonpins.jpg


The wires were then threaded through a conviently placed hole and the main cover was re-attached.
throughhole.jpg


Testing the inductive charger on the Touchstone showed that the "top" contact was the positive and the lower was the negative. Then the wires were shortened and soldered to the contacts on the Pixi cover:
connectedf.jpg


All that was left was to put the battery back in, close it up, and test on the Touchstone. Here's the Nexus on the Touchstone:
onpuck.jpg


And here's a front view:
chargingr.jpg


You can see that it shows that it's charging both in the notification tray and the lockout screen. It seems to charge about as fast as the regular plug in charger, but I haven't done any real testing on it yet. One complaint is that the back of the Nexus is fairly slick and doesn't grab onto the surface Touchstone. There are four magnets on the Touchstone that align it, but it definitely needs more friction to keep it from sliding off when bumped.
 

T4rd

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Nice, is there any way to bump the Amperage up to 1 Amp (AC speed). USB Speed (550 mAh?) seems to barely charge it.

Awesome mod though ;).
 

Fenris_Ulf

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Not sure. I'll have to test out charging time and see what the actual rate is. I know the Touchstone doesn't like power plugs with less than an amp, so it should be capable of a fair amount of current. I don't think anyone but Samsung knows what the charging capabilities of the pogo pins are. I've read that the contact resistance is comparable to micro USB. This mod is nice to charge at night, the Touchstone makes a nice stand to put the phone in clock mode. Not sure how it will work in the car, 4G and navigation may drain faster than any charger can keep up. But at least it's convenient and easy to just drop it on and then pick it up.
 

hhairplane

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Jan 4, 2012
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Do you have any idea if NFC works? Do you know if this still works with a case? Thanks and good work.
 

collegeboy69us

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wow - that's awesome. I don't own the 4G Nexus yet, but if I do wind up getting one once my contract is up with sprint (in April) this looks like a totally worthwhile mod. And for whatever reason if you had to return it to stock, it would take no time at all with no damage!
 

Gorilla

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That's definitely pretty cool. I don't really have the guts to take apart my brand new G-nex, but I'll definitely bookmark this page in case I want to try this out some time.
 

Fenris_Ulf

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Do you have any idea if NFC works? Do you know if this still works with a case? Thanks and good work.

Haven't tried NFC yet, there's nowhere that I know of around here that takes it. It should still work, while the coil might block a bit, it shouldn't be enough to totally block the NFC. A case would have to be as thin as possible, probably a silicone skin. Too thick and the magnets won't contact and hold it to the puck. Anything thicker than about 3-4 business cards would be too much I think.
 

yang901

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Jan 9, 2012
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Thanks it works charmingly. One question is I clone your mod and find out the charging state shows (indication) almost 10sec delay after the 5V power/ground being plug into pogo pins. Is this only me or you'r in same condition? :(

Thanks in advance.
 

Khadgar

Weaksauce
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Feb 18, 2006
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If anyone does this mod and is able to try NFC, let us know. I'm definitely interested in trying this out, but I don't want to lose NFC.

Thanks OP for the guide!!
 

Fenris_Ulf

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Thanks it works charmingly. One question is I clone your mod and find out the charging state shows (indication) almost 10sec delay after the 5V power/ground being plug into pogo pins. Is this only me or you'r in same condition? :(

Thanks in advance.

I get about a 2-3 second delay, but that's pretty normal with most phones when you plug in the USB connector.

Khadgar -
The discs are rare earth magnets as far as I can tell. If you can, I'd use slightly bigger/stronger magnets to hold it more firmly - the GNEX plastic is quite slippery compared to the rubberized Pixi backing.
 

mikexilva

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Jan 11, 2012
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If it's possible to do what you show here, why don't we see an acessory case from samsung or Powermat that have the induction receiver coil embeeded in the back and also make the proper contacts in Galay Nexus pogo pins ?

Don't you agree it would be a very good extra for protecting and dock charging, and offcourse it would save the phone's micro-usb plug for other usage...

I'm sure it would be a success case. And some people that don't buy cases because it adds a bit of bulk to the phone, wouldn't mind buying this one because it adds features and simplicity... for instance charging the phone in Samsung original 3 pin pogo contact desktop dock with a protective case on the phone it's not possible...

It could use a bigger coil if needed, because there is such space in the back of Galaxy Nexus.. I'm using i9250 (European HSPA+ Galaxy Nexus) and it has a smaller internal battery and a bit recessed back cover, so the coil would fit there perfectly without adding much bulkiness to the phone with the case...
 
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mikexilva

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Jan 11, 2012
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Won't the magnets impact your compass functionality?

I suppose it should interfere, but I wouldn't mind removing the magnets, and draw the outline of the phone in a pad so it could be manually aligned, or have a pad with some sort of nails to to keep the phone in place.
 

Fenris_Ulf

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If it's possible to do what you show here, why don't we see an acessory case from samsung or Powermat that have the induction receiver coil embeeded in the back and also make the proper contacts in Galay Nexus pogo pins ?

Don't you agree it would be a very good extra for protecting and dock charging, and offcourse it would save the phone's micro-usb plug for other usage...

I'm sure it would be a success case. And some people that don't buy cases because it adds a bit of bulk to the phone, wouldn't mind buying this one because it adds features and simplicity... for instance charging the phone in Samsung original 3 pin pogo contact desktop dock with a protective case on the phone it's not possible...

It could use a bigger coil if needed, because there is such space in the back of Galaxy Nexus.. I'm using i9250 (European HSPA+ Galaxy Nexus) and it has a smaller internal battery and a bit recessed back cover, so the coil would fit there perfectly without adding much bulkiness to the phone with the case...

Because the powermat and the specialty backs are expensive. There aren't as many GNex handsets as there are, say, Iphones, so the market is somewhat more limited and it would take longer to recoup investment on manufacturing dies, testing, etc. And to get good contact on the pogo pins, you're going to need a decently stiff case, which might ruin the sleek lines of the Gnex. If you think there's a market for this, why don't you make a Gnex case with these features?
 

Fenris_Ulf

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Last night I tested out the NFC at a PayPass reader at Whole Foods. It works just fine, absoloutely no problems.

I'm thinking about version 2 of this mod by turning the stock Verizon silicone skin into an inductive charging case.
 

mavalpha

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I was considering doing something similar with one of my old phones, but my biggest fear was that the phone wouldn't be able to stop charging when the battery was full. I guess yours doesn't have this problem since you're soldering directly to an intended charging circuit anyway?
 

Fenris_Ulf

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You have to go through the charging circuit to be safe. I'm not sure if the batteries have a built in protection circuit. I know most laptop packs have protective circuitry, but I don't think there's much space in cell phone batteries for the circuitry. Plus, it's really not any more difficult to attach to the charging circuitry (pogo pins or USB port) than directly to the battery.
 

Fenris_Ulf

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Yes. I'm very slowly working on it. I plan to make a thin pogo plug piece that fits on the side and install it and the inductive charger in a silicone skin. Works the same, removable, doesn't modify the handset itself. I just need time and some spare bucks to get all the pieces.
 
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Any idea where to get the piece that can interact with the pogo pins? I found some on mouser.com but they seem too large to fit on my case.
 
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I am using this idea and trying to make a inductive sleeve, using a silcon sleeve i have. i have everything hooked up, when I test I get power. But, when I touch the wires to the correct pogo pins I get a quick response from the nexus saying "not charging" then nothing. I am trying to do this without taking apart the phone. The only thing I notice is I am using the charging piece from a pre instead of a pixi. Does anyone have any ideas?

I will continue to work on it and update with any progress.
 

collegeboy69us

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I Got my palm pixi back and base today in the mail -- this is a pretty straightforward mod.

Using nothing but a razor and my fingernails I was able to get he charging coil positioned and installed on the Nexus back cover with ease. Just take your time and peel slowly/surely and it comes off clean from the pixi back.

It lines up and fits perfect on the Nexus back -- the magnets are strong enough to hold the nexus with ease. The back cover on the nexus requires no modification to fit snugly and securely to the phone itself. No real bulging that I can see either.

Now the hard part for me which I can't finish today is connecting the internal pogo pin connectors to the pins on the charge coil.

I plan to use a combination of copper tape and clear tape to route a circuit. I know the OP used small wires, I want it to be super compact/clean though :)

I hope home depot or some local place has it, I'd hate to have to wait a week for 5 dollars worth of copper tape to arrive via amazon. Might give this a shot too: http://www.homedepot.com/h_d1/N-5yc...3&langId=-1&keyword=copper+tape&storeId=10051
 

jakubp12

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Any of you guys that did this mod in the North Jersey Area? I would love to do this mod, but don't wanna screw up my new phone I just ordered lol.
 

Headcase_Fargone

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Mar 25, 2010
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So for those of you here that have done this mod, how easy or difficult was it prying the backing away from the screen? That's the only part of this process that really scares me...
 

cpw7922

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Nov 7, 2012
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Has anyone found a good way to connect to the pogo pins without opening up the case?
 

Fenris_Ulf

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I tried using a case with the Palm inductive unit mounted on the inside of the case. Unfortunately, I couldn't get good enough pressure on the pins and the wires were too bulky, so I went back to the original mod. A custom hard case could be made, but there's probably not enough demand.
 
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So it's been confirmed that NFC works fine off the dock, but what about on the dock? The reason I ask is that I have NFC tags at the spots where I charge my phone (Desk, nightstand, car dock) that activate certain location related functions. Will the electric field generated by the inductive charger interfere with NFC? I assume it would, but if someone who's done this mod could test NFC out on the dock, I'd appreciate it. At any rate, this mod is pretty genius, and props to the OP. I might go ahead and do this mod, and if it ends up interfering with NFC, I may have to investigate some Tasker trickery.
 

dieseldog49

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Dang, thats sweet. I have a G Nexus 32gb myself and love it. I may try this down the road.
 

Fenris_Ulf

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So it's been confirmed that NFC works fine off the dock, but what about on the dock? The reason I ask is that I have NFC tags at the spots where I charge my phone (Desk, nightstand, car dock) that activate certain location related functions. Will the electric field generated by the inductive charger interfere with NFC? I assume it would, but if someone who's done this mod could test NFC out on the dock, I'd appreciate it. At any rate, this mod is pretty genius, and props to the OP. I might go ahead and do this mod, and if it ends up interfering with NFC, I may have to investigate some Tasker trickery.

I don't really know. I've never tried NFC while on the dock. I think I'll try connecting to my wife's SG III while charging. I'll let you know how it goes.
 
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