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touchpad charger with ipad usb
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Old 07/05/2011, 10:03 PM   #1 (permalink)
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Can I use the I pad USB charger with the touchpad since it is 10w and will it charge faster?
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Old 07/05/2011, 11:05 PM   #2 (permalink)
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Originally Posted by Mmoran27 View Post
Can I use the I pad USB charger with the touchpad since it is 10w and will it charge faster?
I don't think you quite understand electronics. The 10W power supply means the unit can draw up to 10 watts, not that 10 watts will be forced into the unit. The unit will only take in as much power as it pulls. If the TouchPad only draws 8W (for example), then with a 10W power supply it will still only draw 8 watts. It won't charge any faster.

The plug is a simple AC/DC conterter. It has a throughput of only 10W. This is mainly due to it's size. It takes the 110VAC and converts it to a VDC that the TouchPad can use. (I have yet to receive mine, so I cannot say what the output voltage is but I have a feeling it is 5VDC).

That being said, be sure the voltage levels are the same. A higher voltage could damage your TouchPad. But USB is pretty standard so the voltage levels should be the same.
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Old 07/05/2011, 11:46 PM   #3 (permalink)
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Look at the plug itself. You will see something along the lines of (these are the numbers off my Veer's plug):
Input: 100-240V~ 50/60Hz 0.2A
Output: 5V= 1.0A

What this says is the plug will work on almost every power system in the world. But the plug itself only pulls UP TO 0.2 amps. So the input would be somewhere between 20W and 48W, though I'm betting closer to 20W. The output is in DC voltage and is set at 5W.

Why only 5W when the input is 20W? Unfortunately, converting from VAC to VDC is not a very efficient process especially when dealing with two different voltage levels.

Watts = Volts * Amps. So as the voltage goes down, so does the available power (watts). Despite a five fold increase in Amps, the voltage drops over 95%.

So a 10W plug at 5VDC will have a current of 2A. These are the numbers you need to look at. If the output voltage on the iPad differs than that on the TouchPad, DO NOT USE IT! If the iPad output Amps is LOWER than that of the TouchPad, it just won't work.

I'll be getting my TouchPad in a couple days. When I do, I'll look at the numbers and get back on here (assuming no one else jumps in first).
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Old 07/05/2011, 11:56 PM   #4 (permalink)
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Originally Posted by bobsentell View Post
Look at the plug itself. You will see something along the lines of (these are the numbers off my Veer's plug):
Input: 100-240V~ 50/60Hz 0.2A
Output: 5V= 1.0A
...
Mine says:

Input: 100-240v 50-60Hz 0.4A
Output 5.3v = 2.0A
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Old 07/06/2011, 12:01 AM   #5 (permalink)
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Originally Posted by hparsons View Post
Mine says:

Input: 100-240v 50-60Hz 0.4A
Output 5.3v = 2.0A
The plug I'm using to charge my iPad1 say 5V = 1.0A and it charges the iPad just fine.

That being said, the TouchPad may indeed be pulling more power than the iPad plug can dish out. The 5.3V shouldn't be a concern. That is usually well within the voltage range of most 5V chips (unless HP got proactive and is using milspec chips).

But worst case, the TouchPad gives you a charge error.

The 5.3V actually equates to 10.6W. But I guess they are accounting for the resistance in the USB cable.
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Old 07/06/2011, 12:12 AM   #6 (permalink)
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I picked up a Griffin wall charger for iPad- listed specs are 5v 2.1A, it gives a charging error on the touchPad. I didn't keep it since the hP charger is ~$20 on Amazon.
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Old 07/06/2011, 12:21 AM   #7 (permalink)
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That's interesting. I'll break out my O-scope when my TouchPad arrives.

-- Sent from my Palm Veer using Forums
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Old 07/06/2011, 05:07 PM   #8 (permalink)
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The Touchpad is very fussy about using other chargers. It will give often give this message...

To reliably charge, use the cable and power adapter that came with your device and plug it into an outlet.

In my very limited experience. Wall chargers from the iPad and Pre seem to charge the touchpad. A simple USB connection into a PC, either charges slowly or not at all.
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Old 08/22/2011, 11:55 PM   #9 (permalink)
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Both tablets are busy being fussy. The iPad uses a particular resistor between the data lines at the charger to communicate that it is the genuine high current power source. I bet HP does something similar, only with a different resistor value. They both mutually see the other's charger as a big fat unknown, and only safe to pull .5 amps (though you're really supposed to ask for >.1 first).

How well does the HP handle trickle charging, once it knows that there is no genuine HP charger at the other end? The iPad can get by fine at 1:1 ratio - it can either stand still while in use (the Not Charging prompt), or take an hour to charge an hour of battery (while asleep). In the two days I've had the TouchPad, I haven't put it down long enough to check slow charging.
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Old 08/23/2011, 11:49 AM   #10 (permalink)
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Originally Posted by rotopenguin View Post
Both tablets are busy being fussy. The iPad uses a particular resistor between the data lines at the charger to communicate that it is the genuine high current power source. I bet HP does something similar, only with a different resistor value. They both mutually see the other's charger as a big fat unknown, and only safe to pull .5 amps (though you're really supposed to ask for >.1 first).

How well does the HP handle trickle charging, once it knows that there is no genuine HP charger at the other end? The iPad can get by fine at 1:1 ratio - it can either stand still while in use (the Not Charging prompt), or take an hour to charge an hour of battery (while asleep). In the two days I've had the TouchPad, I haven't put it down long enough to check slow charging.
Mine has completely died and it's been ONE hour already connected to my iPad 2's 10w Wall Charger and everytime I try to turn the TP on, it keeps saying the "to reliably charge this device, use the included charger..." message and it won't turn on at all.
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