View Poll Results: If I was buying a Car Charger for my TouchPad:

19. You may not vote on this poll
  • A single Port supplying 2.1A is adequate

    8 42.11%
  • A Second Port is desirable but NOT at additional cost

    2 10.53%
  • A Second Port for VEER/ Pre is worth an $5 more

    9 47.37%
  • A Second Port configured for the iPhone is worth $10 more

    0 0%
  • I have suggestions - I will PM you

    0 0%
Results 1 to 7 of 7
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  • 1 Post By Wheel_nut
  1.    #1  
    The Chargers I am currently building are based on a Dual Port unit (see my Avatar) supplying 2.1 Amps which is comfortably adequate to power a TouchPad and a VEER or Pre concurrently.

    However, I am having problems sourcing the Raw unit and am considering re-designing around a different Raw unit. I would like your opinion in this poll on which functions are important relative to others.
    Last edited by Wheel_nut; 01/21/2012 at 11:37 AM.
  2. #2  
    Have you seen my post regarding this in another thread?

    It's a $5 unit (shipping is free) and is a four-port unit. Modifying two of the ports to supply 2.1A (total) means removing two resistors and making a solder bridge. The other two ports remain for other devices unless you modify them, too. Total system current draw is 2.1A max. The onboard buck switching regulator can supply max of 3.0 amps, but entire system draw is limited to 2.1A.
    Last edited by jblather; 01/22/2012 at 03:50 AM.
  3.    #3  
    Yes, I saw your post and your experience with the Four port device. I don't want to use this device because it presents an inadvertent risk that the user will leave it plugged into the car and two or more ports are used concurrently, overloading the device.

    The hazard exists because the "generic" spec for USB Charging states that if the Data Lines are bridged, a connected device can draw up to 5 Amps. Yes, this hazard also exists with a single port device but is exacerbated when a device rated at 2.1A presents four Ports. With many Smartphones, Music Players. SatNav devices etc. used in cars today, I don't think I want to offer this.

    I have not have any of my chargers fail when used with the TouchPad, VEER, Pre or even an iPhone (I have supplied this configuration). I had one user buy one because he believed that the Bridged Data lines made it suitable for his ZTE Blade. It wasn't!

    Regarding your experience that using one of the existing ~51K Potential Dividers rather than the 240K/ 300K divider used by HP, you will see in the early pages of the main thread that I initially reported that this worked for me but I later amended that post because when I tried it again with a discharged TouchPad, it didn't charge at full rate but alarmingly, the TouchPad became erratic in responding to the Touchscreen and vKeyboard. Because of this, I only make them with the HP prescribed 240K/300K Potential divider.

    Thank you for sharing your experience. The lesson is that YMMV
    jblather likes this.
  4. noseph's Avatar
    727 Posts
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    758 Global Posts
    I voted for option 3. My main use for the car charger is extended travel and web access. This is accomplished thru FreeTether on my Pre2, and if not connected to a power source drains the battery very quickly. I cannot say enough about the service you have offered this community.
    Quidquid Latine dictum sit, altum sonatur.

    Palm III -> Palm V -> Viewsonic Pocket PC V36 -> Treo 650 -> Samsung i760 ->
    Palm Pre Plus -> Palm Pre 2 > Samsung Galaxy Nexus & HP TouchPad

    Android 4.1 - Samsung Galaxy Nexus
    CM9 Alpha 2 Official Nightly w/WebCM9 0.4 - HP TouchPad

    Twitter: @noseph47
  5. #5  

    I see what you are saying. If devices' current draw is over the 2.1A limit, the 1A fuse will blow (in the adapter) and that could really frustrate the user. Worse, the user could easily replace the 1A fuse with a bigger one and this would be a fire hazard.

    Thanks for the detailed reply. I have not tried to use it with my TP's battery fully discharged. I will have to try that sometime.
  6.    #6  
    I am down to my last one (other than a Griffin I modified with one port for the TouchPad and the other for the iPhone) so I think I will stick with my current design and build another batch of the two port design shown in my Avatar.

    Thanks to all of you who gave me your opinion. Although evenly divided, it is easier for me to stick to one design rather than build two types.
  7.    #7  
    In my quest for an "easy to modify" Car Charger, I have bought a couple of units which make it easier to modify one port whilst leaving the other configured to the Apple Standard.

    PM me if you require this configuration.

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