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How to get Full Power Charge (Mobile battery, car, ...) for HP Touchpad!
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Old 05/05/2012, 04:23 AM   #1 (permalink)
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Hi All out there!

As of the investigations of Wheel_Nut in the car charger thread, I want to show my final solution which with I am able to charge the HP Touchpads even with a mobile charger, car charger, etc...

Prerequisites:
- You ALWAYS have to assure yourself, that the chosen power source provides at least 5V @ 2A (5,1-5,3V and >2A is always fine of course)!
- Every test is done with HP Touchpad 16GB, HP Touchpad 32GB
- Every test is done with latest WebOS and Android CM7 and Android CM9

Test Equipment:
- Tested Mobile chargers: Blackfox PowerBomb 10000, Power.Guy DX.5000
- Self Made Charger cable

Now to the topic:
There are 2 possibilities to get full charging power of nearly 2Amps@5V of the power source: In the power source itself OR in the charging cable. The common goal is to show the HP Touchpad a well defined voltage and impedance level on the USB data lines, as it reads in hardware and therefore independent of the used OS which power level it should use for charging.
As I don't want to break the cases of any of my chargers, I decided to do the modification outside of the charger and therefore on the cables side.
I decided to get a HTC microUSB cable (like that one which came with my HTC Sensation), with which I have good experience in concern of quality, safety of electrical and mechanical connection, reliability, etc. I then cutted the cable around 30cm (1 ft.) after the microUSB side and assembled a new standard USB A-type male connector from eBay (these 4 pieces connectors with top shielding, bottom shielding, plastic housing and connector part).
The goal within this USB A connector is to implement a bridge between the two data lines and adding 2 additional resistors of 300kOhm between Ground and the data lines and 240kOhm between the data lines and 5V. I did this with cutting a little bit off of the white plastic of the connector part in front of the solder pads and the solder pads itself and two 1206 resistors (green in the pictures). Important is to NOT connect the USB data lines of the USB A connector part again to the white and green cables! ONLY the resistors have to be connected to the white and green cables, NEVER the USB A connector part as this could lead to wrong reading at least of the impedance from the Touchpads charging logic!

Now this looks like this:
https://skydrive.live.com/redir.aspx...HGluOYU7sXLZ_c
https://skydrive.live.com/redir.aspx...EUw7nrKEUTEry8
and finally
https://skydrive.live.com/redir.aspx...DpDm1-d-Px-X4w

Done!

Now lets have a look on the power charts. This is done within Android CM9 and the "Batter Monitor Widget" app.

Charging level:
https://skydrive.live.com/redir.aspx...KOSGCUpt-Oek50

Charging current:
https://skydrive.live.com/redir.aspx...CXg1YXsQPkHFWs

Charging voltage:
https://skydrive.live.com/redir.aspx...GXIBqa64DSTgiI

As we can see here, the complete charge from 1% or 2% to 100% is done completely within 4,5 hours of a pocket battery charger (in this case the PowerBomb 10000) with peak current of around 1,8Amps. The difference to full 2 Amps is only 10%, I think it's about the current, the Touchpad draws in general while it's powered on. This reduces the charging current slightly but this is not a big deal. I assume we would get full 2Amps if the Touchpad is completely switched off, but then I wouldn't have been able to get the diagrams... ;-)
Furthermore we can see the charging logic adjusting the charging current by itself by the means of cell voltage, temperature and time. Everything's quite fine! :-)

I used this now for 2 weeks and it works like a charm in every case. Awesome!

Once again: Thanks to Wheel_Nut for figuring out the electrical part of this. Great work!

Have Fun! :-)
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Old 05/06/2012, 09:20 PM   #2 (permalink)
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The other option is to modify your charger socket the same way, that way you can use standard micro usb cable for charging and data.

Good Work.
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Old 05/07/2012, 07:47 AM   #3 (permalink)
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Hi Firepower!

Thanks for the reply. Yes, it's a solution I can live with without problems. Looks nice and is reliable and convenient.

As to your comment: I described both ways. Solution 1: Exactly what you mean, and solution 2: what I did. I can NOT do it in the source - that's why I wrote "As I don't want to break the cases of any of my chargers..." ;-)

Solution 1 may work in car chargers which can be disassembled and reassembled, no problem. And this is of course the better way, because one cannot "overload" the power source with the modified cable. But in my case with the mobile battery chargers the cases are "single assemble / destroy by opening". Thats why I go with solution 2.

But you are right: Additionally I will modify a car charger with solution 1 when I get one! :-)
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Old 06/29/2012, 12:45 AM   #4 (permalink)
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Hi All out there!...

The goal within this USB A connector is to implement a bridge between the two data lines and adding 2 additional resistors of 300kOhm between Ground and the data lines and 240kOhm between the data lines and 5V. I did this with cutting a little bit off of the white plastic of the connector part in front of the solder pads and the solder pads itself and two 1206 resistors (green in the pictures). Important is to NOT connect the USB data lines of the USB A connector part again to the white and green cables! ONLY the resistors have to be connected to the white and green cables, NEVER the USB A connector part as this could lead to wrong reading at least of the impedance from the Touchpads charging logic!

Does the resistor watt capacity matter in this case? I've got a mess of metal film resistors laying around...

thanks!
chris
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Old 06/29/2012, 04:29 AM   #5 (permalink)
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Originally Posted by chriswillis View Post
Does the resistor watt capacity matter in this case? I've got a mess of metal film resistors laying around...

thanks!
chris
No, the power dissipation is very low so the smaller the better.
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Old 07/01/2012, 12:44 PM   #6 (permalink)
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Does the resistor watt capacity matter in this case? I've got a mess of metal film resistors laying around...

thanks!
chris
Hi Chris!

As Wheelnut says: NO - not really. The charging power is not driven over these resistors, so don't worry, if they have small power. I only took 1206 at the time of my posting, because I assembled them in the USB connector directly and the 1206 size fits directly the USB connector's pitch.
In my last project (USB-to-USB insertion adapter) I assembled 0603 size - no problem. Also 0402 would not be a serious problem. ;-)
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Old 08/04/2012, 03:22 AM   #7 (permalink)
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In addition to my last reply, here again a photo of these insertion adapters, which I created in the meanwhile for charging the HP Touchpad with full power of every capable USB power source:

http://sdrv.ms/NYsZhp

The upper one is for charging @ full power, the lower one is for explicitely NOT charging the Touchpad.

I use this regularly for the data only transmission purposes when I set the Touchpad to USB OTG mode (connecting external mouse, cardreader, USB sticks, etc., which needs external power). Because of the lack that the Touchpad cannot deliver power over USB in the USB OTG mode, one has to deliver the power externally. But if you use a external power source connected to the USB port, the TP will start trickle charging without my 2. adapter and will drain the external power source. With the 2. adapter I prevent the Touchpad draining the external power source, which I only want for powering the external USB devices. ;-)

Other tested devices in the meanwhile have been:
- MiPow Power Tube SP 5500
- Goobay NTS90W Universal power adapter 12V - 22V (selectable) with different adapters (for notebooks also) and USB 5V/2A

Of course, the MiPow cannot charge the TP completely, because it has only 5500mAh, but in general it works and can give a quick additional power, when needed to enhance the TPs lifetime for watching videos, etc.

The Goobay Universal power wall adapter is now my preferred power source for everything: Handy, Touchpad, Netbook, Notebook - it can handle all devices, most of them also at the same time. Really awesome! :-)

Last edited by BGrosse; 08/04/2012 at 03:30 AM.
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Old 08/04/2012, 06:56 AM   #8 (permalink)
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Hi BGrosse, Nice neat job!

Why do you need the second interposer for OTG use? Surely, the Powered Hub or Y Cable can plug directly into the OTG Cable. What function have you built into that second interposer?

Can you point me at a source for the raw interposers and USB A Plug that you use. I have found a rewirable USB A Plug but without the plastic shroud and all of the interposers I have found have injection moulded covers rather than the snap-on covers that yours have.
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Old 08/05/2012, 02:27 PM   #9 (permalink)
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Hi Wheelnut! Nice to read again from you! :-)

Thanks for your kind feedback. In the meanwhile I tested very much "material" together with the Touchpad and its USB capability in concern of the OTG mode. The first of all was the suggestion from here (was it you...?) with that solar powered USB hub from china. Then followed by other USB hubs with integrated power and not, then other power sources (battery and wall adapters), USB drives, USB sticks, USB mice with RF transceivers, USB Card readers (single and multi standard) and so on. And I made many cables on my own, especially USB Y cables, power cables and and and...
I think I have to start a new thread with all the stuff tested and how it behaves and so on. ;-)

But to your question:
During all the time with testing these several pieces of hardware, I found that the TP sometimes starts charging, sometimes not. Depending on the cables and the power source I used at that time. Given, that the external power source should not charge the TP but power the connected USB devices, I decided to make another interposer which simply "cuts" the 5V line into the TP. So the data lines are fed through and of course also GND. Done this way data communication is possible, but not feeding power to the TP.
In conjunction with all the tested hardware (USB hubs, USB devices and power sources) the only SAFE way of using all the USB sticks or memory cards with the several USB Card readers was with that interposer. Before I made that one, I randomly got communication problems with this card reader, that memory card or this day one setup worked, the other day not, sometimes the TP drains the external battery - sometimes not (which leads to that communication problems where current peaks while recognizing USB devices or transferring data from/to USB devices leads to randomly lost USB devices, etc.). Since I used that interposer, I never had any problems.

As a source for that interposers I also searched the net for a long time. The final solution is from china (of course) and intentionally made for charging Samsung's P1000. I just removed all the resistors inside and put in whatever resistors I needed. Actually I made one for charging the TP, then the cutted one for data transmissions only for the TP and also a third one for charging NOKIA mobile phones (Nokias need another resistor set inside than HP used for the TP to get full power charge).

Here you go: USB Power Adapter for Samsung P1000 - Free Shipping - DealExtreme

I also bought this one: USB Male to Female Data / Charging Switch Adapter Cable for Samsung Galaxy Tab P7500 + More - Black - Free Shipping - DealExtreme
and removed the PCB inside completely and engineered my own electronic to charge my R/C mini helicopters with any USB power supply (preferred the battery ones)... ;-)

YES, tell me crazy, but doing some PCBs for this or that job is not a big deal for me and I like professional results! I didn't yet take photos from that one but if you want, I can share them too. Not a big deal.

After all the testings I have done, one mobile battery for charging with one Y cable and an adapter and I can charge ANYTHING (my mobile phone, my wifes phone, the TP, the PSP, my heli, and and and...). Life is really fun when one can do his own electronis! :-)
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Old 08/06/2012, 01:21 PM   #10 (permalink)
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Hi BGrosse,

Thank you for the linky to the DealExtreme interposer.

The only time that I have managed to confuse the TouchPad between OTG mode and Charging Mode is when I was trying to make a very simple powered OTG adapter using this device: AA Battery Emergency USB Charger With Flashlight For iPhone 4G 3G 3GS ipod White | eBay

I cut the USB A Socket off an OTG Cable and soldered the cable into the USB A Socket in the device. This effectively makes a battery powered Y Cable with a USB Socket for a USB Pen Drive. When testing, I got some incidents of the TouchPad trying to charge (albeit in low power mode) from the battery converter. I put that down to the TouchPad being slow to sense the OTG bridge between pins 4 and 5 of the MicroUSB Plug and so I always plugged in the MicroUSB Plug, then waited a few seconds before switching on the Voltage converter.

I have not persevered with this because whereas it works fine with (some) USB Pen Drives, it doesnt work with MicroSD to USB adapters which is what I mainly use. For some strange reason, the MicroSD or SD cards need to be connected through a Hub for the TouchPad to recognise them as OTG devices.

Like you, I hate carrying a plethora of Chargers and prefer to carry a single Power source and adapt it to the specifications required by my portable devices. Fortunately, there seems to be a convergence in the industry around the MicroUSB plug though most of the generic MicroUSB cables sold by Amazon and eBay have too high an impedance to carry the 2 Amps required. The only cables that work for me are the ORIGINAL HP cables and the ORIGINAL Nokia cable tha came with my N900. All of the cables purporting to be "original" Nokia cables have an impedance of 2 - 3 Ohms per conductor and at 2 Amps, the volt drop produces next to nothing at the Load.

Last edited by Wheel_nut; 08/06/2012 at 02:27 PM.
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Old 08/08/2012, 03:39 PM   #11 (permalink)
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humm, I've looked for 240k and 300k at radio shack with no luck. I've got a ton of random ones but I've only got 220k, 270k 330k.

so, how close is close enough?

thanks!
Chris
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Old 08/08/2012, 04:55 PM   #12 (permalink)
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Originally Posted by chriswillis View Post
humm, I've looked for 240k and 300k at radio shack with no luck. I've got a ton of random ones but I've only got 220k, 270k 330k.

so, how close is close enough?

thanks!
Chris
220k and 270k "should" be close enough for jazz
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Old 10/14/2012, 10:42 PM   #13 (permalink)
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This sounds like a fantastic answer to the problem all of us are running into. Since I am not as sophisticated or brave enough to attempt such a cable mod, have you considered creating such cables for those of us that would be willing to purchase?

Thanks,

jax1111
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Old 10/15/2012, 01:29 PM   #14 (permalink)
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This sounds like a fantastic answer to the problem all of us are running into. Since I am not as sophisticated or brave enough to attempt such a cable mod, have you considered creating such cables for those of us that would be willing to purchase?

Thanks,

jax1111
While agreeing that this seems like an elegant solution to the problem, it comes with a serious hazard. This modified cable or interposer allows the TouchPad to draw up to 2000 mA from whatever source it is plugged into. Thus if it is plugged into a 500mA source (which is the USB 2.0 Specification), it can damage the source or overheat the source with dire consequences.

BGrosse has described these hazards in his thread and leaves it to a competent user to act responsibly.

Whereas I will modify a Car Charger or Mains Charger INTERNALLY and safely to supply the TouchPad's requirement, I would be irresponsible for me to supply such a cable or interposer so, sorry but I will not.

I trust that you understand my rationale.
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Old 11/10/2012, 11:39 AM   #15 (permalink)
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There is nothing else to say. Wheel_nut points out exactly, what's the point with all cable and adapters: the user has to know, what he is doing. Just blindly connect together what is physically possible through the USB standard connectors can - in the worst case - result in a fried Touchpad. Especially whith those power sources engineered and assembled in China! Beware of them! They mostly lack on "safety" circuits such as overvoltage, overcurrent and temperature protection.
Of course the cables and adapters work perfectly and are a perfect solution when one knows what he is doing. But I am definitely on Whell_nut's side: as a manufacturer and supplier on the "market" I would be responsibly for any errors and conformance checks every electronics manufacturer has to fulfill today. So it's also a question of actual laws, if Wheel_nut or me could supply cables and adapters to the market.

@Wheel_nut:
Beside that, I engineered a new "power supply" or better "Charger" for all my mobile devices. This includes the HP Touchpad, all Nokia mobile phones as long as standard USB devices (GPS mice, Sony PSP, HTC phones, etc.) and - just for fun - mostly of the tiny R/C Helicopters which are on the market and have a power supply of 4,3V @ 1A.
My focus was to create a "little box" which can charge all of my devices with the bonus of a very high efficiency. Why bonus? Easy: I want to be able to connect it directly to PowerTraveller's Solarmonkey for "light loads". And also to the PowerMonkey for heavy loads. And also use this charger together with my mobile batteries, where loss of energy leads to less "working time". :-)
The first shot looks like this:

Front view: http://sdrv.ms/ROSsvi

Rear view: http://sdrv.ms/Qwzm06

The layout of the PCB is specially designed for use with the housing of a D-LINK USB Hub:
DUB-H4 (the old version of course!): http://sdrv.ms/STi3oc

So I created 3 different power stages:
Port 1: HP Touchpad (5,25V @ 2,5A - with detection resistors for HP Touchpad)
Port 2: R/C Helicopters (4,3V @ 1A)
Port 3: Nokia Phones (5,00V @ 2A - with detection resistors for Nokia devices)
Port 4: Generic USB devices (shared with Port 3, but without the detection resistors)

Every channel has it's own power LED (red/green/blue) for signaling the amperage level which the connected device drains. And the main power LED can signal fails or anything else.

The USB-B port is used only for debugging/terminal purposes. With the firmware (to be developed in the near future) the input voltage (7V to 30V) is monitored as long as the output voltages and amperage levels. Also a controlling of the output current delivered on the 3 different stages is possible (0-100% of their nominal value). And just for fun, there are 3 Touch buttons integrated in the top housing, with which one could adjust the power levels of the channels without connecting a terminal through the USB-B port. Just with some finger touches ("+", "-" and "Enter").

The hardware part is finished and verified successfully. The efficiency with this first shot is 90% and higher for voltages of >12V and >500mA loads. Also in the worst case scenario with slight loads of only 50mA and 24V input voltage, the efficiency is already at 80%. Maximum temperature @ 12V input voltage (i.e. car) and 2A load at Port 1 was 56,8C on the chip's surface. A good value which results also from the high efficiency this design has and if you keep in mind that there is not much copper directly around the chips for cooling and it is only a 2 layer PCB. At least the temperature could be lowered with the help of more copper and vias directly around the chips. But for me this first shot gives excellent values under all conditions so far.

So, what do you think?

Last edited by BGrosse; 11/10/2012 at 12:09 PM.
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Old 12/09/2012, 02:57 AM   #16 (permalink)
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Hi, I have read this thread with interest. I have 4 TouchPad and two Pre3s. Ideally I need them all charging while travelling. Whilst I can charge the Pre3s via the normal vehicle sockets I cannot yet charge the Touchpads. Can your box be modified to suit? Would you be prepared to make and sell two that have TWO dedicated sockets on each?
Thanks
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Old 12/09/2012, 07:10 AM   #17 (permalink)
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Hi, I have read this thread with interest. I have 4 TouchPad and two Pre3s. Ideally I need them all charging while travelling. Whilst I can charge the Pre3s via the normal vehicle sockets I cannot yet charge the Touchpads. Can your box be modified to suit? Would you be prepared to make and sell two that have TWO dedicated sockets on each?
Thanks
I will let BGrosse reply to your query but have you considered that in order to charge FOUR TouchPads and TWO Pre Phones concurrently, you need to provide a minimum of 10 Amps.

You will see from the other thread that several users of my Dual-Port Charger are successfully charging One TouchPad and One Pre (or Veer) Phone concurrently. You could therefore as an alternative solution, use an adapter like this 3 Ways Car Cigarette Lighter Charger Adapter USB Jack | eBay to feed multiple Car Chargers.

... just a lateral thought ...
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Old 12/10/2012, 05:14 PM   #18 (permalink)
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I will let BGrosse reply to your query but have you considered that in order to charge FOUR TouchPads and TWO Pre Phones concurrently, you need to provide a minimum of 10 Amps.

You will see from the other thread that several users of my Dual-Port Charger are successfully charging One TouchPad and One Pre (or Veer) Phone concurrently. You could therefore as an alternative solution, use an adapter like this 3 Ways Car Cigarette Lighter Charger Adapter USB Jack | eBay to feed multiple Car Chargers.

... just a lateral thought ...
Thanks for your reply. Indeed, I already have two of the chargers you mention. I am now looking to charge the Touchstones whilst being used in a vehicle. Do you happen to know of an adequate solution?

My vehicle already has two factory fitted sockets.
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Old 12/10/2012, 08:08 PM   #19 (permalink)
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Thanks for your reply. Indeed, I already have two of the chargers you mention. I am now looking to charge the Touchstones whilst being used in a vehicle. Do you happen to know of an adequate solution?

My vehicle already has two factory fitted sockets.
Not clear on what you are wanting.

If your vehicle already has TWO Cigar Lighter Sockets, are you just wanting the Cigar Lighter chargers midified for charging the Touchpads? If so, see my Avatar.

Are you really wanting to use Touchstones in the car? or did you mean TouchPads?
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Old 12/11/2012, 01:06 PM   #20 (permalink)
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Hi, I have read this thread with interest. I have 4 TouchPad and two Pre3s. Ideally I need them all charging while travelling. Whilst I can charge the Pre3s via the normal vehicle sockets I cannot yet charge the Touchpads. Can your box be modified to suit? Would you be prepared to make and sell two that have TWO dedicated sockets on each?
Thanks
Hi Paul!

Sorry for my late reply. As to your question: of course, my little box can be modified to support min. 3 ports for HP Touchpads. And the 4. port can also be modified to charge the Pre's (when I knew, what resistors they need to charge @ full amperage). Technically spoken, this would be not a big deal.
But I share Wheel_Nut's thoughts about this: we are talking about 8-10 Ampere when the box is fully loaded. That's really heavy! And believe me or not: economically spoken this would be foolish. Why?

Let me explain: I built this box due to the fact, that I recognized in summer this year that Linear Technology put a new DC/DC converter chip on the market with very high efficiency and current control capability. Therefore I decided to spend some hours, engineering a new design with these new chips and a microcontroller for several purposes. After building up the hardware I found the new LT chips are performing very well, the design is rugged and very efficient. But I never cared about the costs of one of those so called "engineering samples" (which I have 3 of at the moment). Without calculating exactly I would assume, it would be around 50 bucks for every of the 3 units. And I don't think, you would pay for that, right?
Another thing is: of course I could bring them on the market, but would have to fulfill every regulation of the countries, in which I will sell the boxes. Again: technically spoken, the boxes are designed carefully in concerns of safety and electromagnetic compatibility but proving all of the tests through official laboratories (which is neccessary for bringing them to the market) would cost several thousands of $$. So I cannot sell them "officially" OR I have to invest in that and make a real big business, so the economical side of this is satisfied. But I think, for this are simply too less Touchpad users that would pay for such a box, even though they can charge everything with it which has a USB port.

Therefore I recommend using the simple china car lightning adapters with a 2 Ampere capability and modify them like Wheel_Nut does. This would be much more cheaper and does it's job normally well as long as they don't "crash" and fry everything which is connected in this moment. That's the big risk of every china electronics. I had this one time with a cheap piece of power converter - and will never use it again if I have the chance to replace it with something I trust. :-)
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