Page 5 of 20 FirstFirst 1234567891015 ... LastLast
Results 81 to 100 of 391
Like Tree71Likes
  1. #81  
    This might be a good solution if you go the inverter route:



    80 Watt Continuous/200 Watt Peak Slim Power Inverter

    Only $17 in the Harbor Freight Store (add $6 for S&H if you order online)
  2. #82  
    Quote Originally Posted by tweak42 View Post
    2.1A is what the iPad is speced for thus many of the manufactures use that as a baseline. Unfortunately there seems to be something proprietary or at least different in the way iPad & Touchpads identify the max output of an adapter. It looks like the only guaranteed way to charge at 2.0A is use an AC inverter.
    or the TP registers any amperage -/+ 2.0A and throws out that alert.
    Has anyone tested if it charges anyway? I thought I read somewhere that the TP will still charge from a computer's USB port, at a slow rate if the screen is off.
  3.    #83  
    Quote Originally Posted by Bockscar View Post
    by using the Battery Monitor app I came up with these results, YMMV
    Touchpad wall charger 1800 mA
    Touchstone 1500 mA
    Pre wall charger 1200 mA
    Palm car charger 1000 mA
    Technocell car charger 700 mA
    USB 2.0 port on my laptop 500 mA

    These are approximate because the app doesn't give live data, I set it to the shortest poll interval of 15 seconds and calculated charge based on change in draw. Since the TP uses apx 1000 mA the Palm car charger should be enough to keep if from dying, however I did not see how much the draw increases when playing a video....
    Quote Originally Posted by tweak42 View Post
    Contrary to all the speculation in this thread, I can confirm a Bravo View Micro2.1B (2.1-amp Compact USB Car Charger) only outputted about 600mA charging to my Touchpad. Purchased in store at FRYS for $10. I'm considering returning it and trying the $20 SCOSCHE.

    To get real numbers I used Govnah to chart "Battery Current", positive (charging) or negative (discharging). Turn off the screen with Govnah running for about 15 sec then quickly unlock and check the current. My Touchpad drains around 600-800mA idle at 50% brightness.

    I don't have one, but has anyone tried using a Dual USB A to Micro B cable? I'm curious if the amperage will stack.
    Quote Originally Posted by gergev View Post
    or the TP registers any amperage -/+ 2.0A and throws out that alert.
    Has anyone tested if it charges anyway? I thought I read somewhere that the TP will still charge from a computer's USB port, at a slow rate if the screen is off.
    yes the TP does still charge, but while in use most forms of charging are not enough to keep up with the drain and will only slow down the rate of discharge. The battery is good enough that I haven't had the need for anything more than my Palm car charger but I do plan on buying an inverter.
  4. #84  
    Quote Originally Posted by shanpalm61 View Post
    reVIVE II - Dual USB Car Charger for iPad
    Walmart has this listed al well.
    Comments please!
    Thanks..
    buy com claims it works with touchpad (even though the scosche website does not)
    Buy.com - Scosche reVIVE II Dual USB Car Charger for HP TouchPad 9.7-inch Tablet Computer

    but there are no reviews.
    Amazon sells for same price, but none of the reviewers mention the TP
  5. #85  
    Quote Originally Posted by gergev View Post
    buy com claims it works with touchpad (even though the scosche website does not)
    Buy.com - Scosche reVIVE II Dual USB Car Charger for HP TouchPad 9.7-inch Tablet Computer

    but there are no reviews.
    Amazon sells for same price, but none of the reviewers mention the TP
    You won't find mention of Touchpad in most of those reviews, but you will find mention of Android tablets. If a given charger doesn't deliver 2amps of charging to an Android tablet, it will be hugely unlikely to deliver those amps to the Touchpad.

    If I recall correctly, some Android tablet owners have tried that specific charger - like so many other 2amp chargers, it provided merely a trickle charge.

    As others have posted, seemingly all of these 3rd party 2amp + charges (yes, every single one so far) seem to be designed specifically to charge the iPad. Because the iPad seems to use different wiring pattern for the high amperage charging than do Android tablets and the Touchpad, these chargers will do nothing more than deliver a trickle charge. Why spend $20 on a 2amp charger when it will only provide 350ma to 500ma trickle charge - sometimes less? Especially when 500ma USB car chargers can be had for less than $2.

    My guess is that until someone rewires a cable or adapter to a compatible wiring pattern, the only way to get a full 2amp car charge will be with the use of an inverter paired with the HP wall charger.
    shanpalm61 likes this.
  6. #86  
    I've sent an email to Champtek tech support about the following to see if it'll send 2.1A to anything:

    CC-210

    Since it ships with a microUSB cable, I'm hoping it isn't as iPad-specific as other products. It is sold at Fry's, but my nearest store is a fairly long drive away.
    shanpalm61 likes this.
  7. #87  
    FYI, I bought a original (wall) palm pre charger $ 3.71 or so on Amazon. It charged the touchpad fine, although it was turned off. Having a background in electronics, there may be a special chip or wiring that indicates if it's an original charger, however in general any charger (car or wall) with 2amp at 5 V should be sufficient to charge the touchpad.
  8. #89  
    Quote Originally Posted by bdbr View Post
    Has anyone tried the "GTMax Black USB Car Charger Vehicle Power Adapter for HP TouchPad"?

    Amazon.com: GTMax Black USB Car Charger Vehicle Power Adapter for HP TouchPad: BlueMall
    Quote Originally Posted by pTeronaut View Post
    I'll tell you next week, Have ordered one today.

    ------- EDIT-------

    Crap, since ordering, a review has appeared stating that it doesn't work as advertised.
    The TP doesn't recognize it as a charger but it trickle charges.

    I have bought the 75W Enercell inverter & USB port from Radio Shack. for $29.99 which as an AC source provides enough power to the HP power adapter.
  9. #90  
    Frys -Lenmar DC to Dual USB (2.1 amp)
    FRYS.com | Lenmar
  10. #91  
    A couple of things to think about here:

    (1) Most of these cheap inverters only have modified sine wive AC output. That is fine for lights and motors, but generally, you want a pure sine wave for electronics. Pure sine wave inverters do exist (they mimic what actually comes out of your wall) but they are much more expensive. While you could use a modified sine wave inverter here and it may be ok, there is some risk of damaging your device with a cheap inverter.

    (2) If you somehow end up cooking your touchpad with a bad inverter, chances are you can't get another one for anything like $99/$149.

    If it were me, I would stay away from a cheap inverter solution on a product where you get no second chances. It may work fine and you'll get away with it, but how much is watching some movie in the car really worth to you?
  11. #92  
    Quote Originally Posted by teamw23 View Post
    A couple of things to think about here:

    (1) Most of these cheap inverters only have modified sine wive AC output. That is fine for lights and motors, but generally, you want a pure sine wave for electronics. Pure sine wave inverters do exist (they mimic what actually comes out of your wall) but they are much more expensive. While you could use a modified sine wave inverter here and it may be ok, there is some risk of damaging your device with a cheap inverter.

    (2) If you somehow end up cooking your touchpad with a bad inverter, chances are you can't get another one for anything like $99/$149.

    If it were me, I would stay away from a cheap inverter solution on a product where you get no second chances. It may work fine and you'll get away with it, but how much is watching some movie in the car really worth to you?
    Wouldn't that apply to most car chargers for mp3 devices, iphones/ipods, cell phones, video players, etc?
  12. #93  
    Quote Originally Posted by rwstarke View Post
    Frys -Lenmar DC to Dual USB (2.1 amp)
    FRYS.com*|*Lenmar
    Please let us know if this works and charges the Touchpad efficiently.

    Thanks!
  13. #94  
    Quote Originally Posted by fljoemon View Post
    Please let us know if this works and charges the Touchpad efficiently.

    Thanks!
    The Lenmar charger is charging the Touchpad. Govnah displays the battery current of about +200 mA when the CPU 1 Freq is 192 MHz . Govnah shows about -650mA when not connected to a charger & about +500mA when connected to AC charger.
  14. #95  
    Quote Originally Posted by gergev View Post
    Wouldn't that apply to most car chargers for mp3 devices, iphones/ipods, cell phones, video players, etc?
    Nope. It is completely different. Electronics run on DC current, just like your car does. So a regular car charger for a cell phone is pulling DC current from the car's electrical system and sending DC current into your phone. That's perfectly safe. But if you use an inverter, you are effectively going DC current, over to AC like what you find in your house, then using an AC adapter like the one plugged into your wall, to go back to DC for the Touchpad. It's the quality of that AC power in the middle of the process which can cause problems. There is lots of info on this out on the web, just do a search for pure sine wave inverters, which are the ones which are safe to use with electronics. Modified sine wave inverters are the cheap kind and they really shouldn't be used with sensitive electronics that can be easily damaged by small variances in power. You'd be much better off finding a DC adapter that will pull enough current to charge the TouchPad, if there is such a thing out there.
  15. #96  
    After reading into issues that android (phone and tablet) users had with charging, I've come to the conclusion that there is something that signals the Touchpad that it's safe to go into "AC" charging mode. As to what the signal is, or if it could be manually engaged by OS I don't know.

    For iPads theres mention of 2 volts on the usb data pins that triggers the 2.1 amp charge. For at least one instance of Android it seems to be connecting the data pins together inside the charger (disassembly required) by soldering a direct bridge or a diode.

    For any electrical engineers out there, it might be possible to analyze and compare the output of a Touchpad AC adapter to any 2000mA usb auto adapter to see what the differences are. Once that's known it maybe possible to modify an auto adapter to fool the Touchpad into switching to "AC" charging mode.
  16. #97  
    Quote Originally Posted by bdbr View Post
    I've sent an email to Champtek tech support about the following to see if it'll send 2.1A to anything:

    CC-210

    Since it ships with a microUSB cable, I'm hoping it isn't as iPad-specific as other products. It is sold at Fry's, but my nearest store is a fairly long drive away.
    I got a reply back from Champtek, but the engineer didn't really seem to know:

    "The charging function starts when the charge voltage (output from CC-210) is higher than the charged device. In this case, it is slightly over 5V.

    As I can not allocate any HP Touchpad near by and the product spec. from HP website is not clear enough. Your question can not be answered properly with getting more information or actual trying. Sorry for that!"

    If I get down to Fry's I'll give this a try. Since it is 2.1A and comes with a mini-USB, it doesn't appear to be iPad-specific at all.
  17. #98  
    Hi, everyone. Just registered to post my findings on the Touchpad's charging circuit.

    It's a relatively basic resistor divider. The Data pins in the middle are shorted out and there's a 250K pull-up resistor to the 5V power supplied as well as a 300K pull-down to Ground.
    The schematic is attached, and on the actual circuit board, the resistors are marked 304 (meaning 30 plus 4 0s) and 39D(? very small, couldn't figure out with a magnifying glass, so just used a multimeter.), respectively.
    Unfortunately, there is no way I can think of to modify other chargers without breaking them open and putting in the resistors in yourself. This may render apple chargers incompatible with the iDevices they were designed for.

    A little bit of playing around with another USB source (my computer) tells that the data pins are used for nothing more than signaling in the first second or so that the touchpad is connected to the official AC adapter.
    It does not initially appear that the voltage on the data pins affects the charging speed, but I need to mess around more with other chargers and the setup and see if I'm wrong.
    Right now, I think the touchpad sucks in power until the load forces the power on the 5V pin to hit some threshold, which appears to be ~4.5V.

    [Of course, nothing is free, and my AC charger had to be disassembled and sacrificed at the altar for this knowledge. ]

    I'll be sure to post any later findings, but right now I'm happy having my touchpad take 1.5A from my solar panel setup . If anyone else on here is of the EE inclination and can confirm, please post!
    Attached Images Attached Images
  18. #99  
    Quote Originally Posted by wilywyrm View Post
    Hi, everyone. Just registered to post my findings on the Touchpad's charging circuit.

    It's a relatively basic resistor divider. The Data pins in the middle are shorted out and there's a 250K pull-up resistor to the 5V power supplied as well as a 300K pull-down to Ground.
    The schematic is attached, and on the actual circuit board, the resistors are marked 304 (meaning 30 plus 4 0s) and 39D(? very small, couldn't figure out with a magnifying glass, so just used a multimeter.), respectively.
    Unfortunately, there is no way I can think of to modify other chargers without breaking them open and putting in the resistors in yourself. This may render apple chargers incompatible with the iDevices they were designed for.

    A little bit of playing around with another USB source (my computer) tells that the data pins are used for nothing more than signaling in the first second or so that the touchpad is connected to the official AC adapter.
    It does not initially appear that the voltage on the data pins affects the charging speed, but I need to mess around more with other chargers and the setup and see if I'm wrong.
    Right now, I think the touchpad sucks in power until the load forces the power on the 5V pin to hit some threshold, which appears to be ~4.5V.

    [Of course, nothing is free, and my AC charger had to be disassembled and sacrificed at the altar for this knowledge. ]

    I'll be sure to post any later findings, but right now I'm happy having my touchpad take 1.5A from my solar panel setup . If anyone else on here is of the EE inclination and can confirm, please post!
    Thanks! And welcome aboard!
  19. #100  
    I experimented some more with the touchpad, and yes, it discriminates based on the presence of the voltage divider. (Wall of text, sorry.)

    The setup was just my computer, in three different configurations. Everything besides what was on the data lines was kept exactly the same to see if it affects anything.
    The first was simply plugging in the cable. On a power saving configuration, the touchpad sucked in a net total of 360mA after turning off the screen. Didn't check voltage under load this time, but I remember it being 4.6-4.8V last night.
    For the second, to simulate a dumb charger that does nothing to data lines, I split a cable I had lying around and cut the green and white data lines. This time around, it only took in enough current to prevent battery drain, so the current hovered around 0 mA, sometimes going up a little, sometimes down a little. Voltage was 4.96V. The touchpad probably does this to avoid damage to itself and the charger from drawing too much current.
    Lastly, I mimicked the AC charger and measured the current with the voltage divider on the data lines, and it was a little over 650mA, with a voltage of 4.46V.

    Normally with the AC charger, the touchpad will draw in somewhere from 1400mA to 1800mA with the screen turned off, so it appears to me that the touchpad's thought process is to be cautious with computers and non-HP chargers, and to suck in as much current (up to ~1800mA) without causing the voltage to drop too far.

    Whether or not any given charger will work depends, but odds are little to none that any given generic charger will have this specific necessary circuit for the touchpad. You can try to charge with them, but the touchpad will only draw about enough to match what it would take from the battery otherwise, or at the very most, not anywhere near the official charger.

    Also, for those who are looking for compatible chargers, please note that some are simply transformers in a plastic shell. These cheap chargers will have voltages lower than what it says on the label at full load (power draw), so they may not even supply a high enough voltage for the touchpad to draw in at that full advertised load. You can still most likely slow down the battery drain while in use, however.
    A charger rated at anywhere from 4.75V to 5.3V should work. The amperage(A) rating should not matter, and the more, the better. The extra current will not force its way through, and as long as the charger pumps out power, it should at least slow the draining compared to leaving it on stand-by.

    For everyone, if you are charging while using, it might speed things up a bit if you changed the CPU governor from "ondemand" to "conservative" or even underclocked the CPU from within govnah so that the CPU doesn't ratch up straight to full and suck up power when you turn the screen back on to check the charge process.

    That's all well and good, but if that's not good enough for you, you can always drive on down to radioshack and pick up some supplies to go modify your own.

    All this, however, may not matter if you decide to put Android on your touchpad. The check for official chargers could either be something programmed into the tablet to check the data pins when power is applied through the port or something wired into the hardware (e.g., a chip that checks for this under the same circumstances.). The former is more likely, but may not be patchable, and the latter would require the same setup under Android.
    Last edited by wilywyrm; 10/14/2011 at 09:10 PM. Reason: Wanted to clear up misconceptions about electricity.
Page 5 of 20 FirstFirst 1234567891015 ... LastLast

Posting Permissions