Shield Tablet touchscreen lag while charging explained
Hello, I have the SHIELD Tablet, and like many of us had problems with a laggy touchscreen when certain chargers were used. It only happened by some, but not by all. Using a USB volt and current meter, I was able to identify the cause of the problem. First some technical background. USB ports and chargers always should give 5 volt. Small variances are allowed, and usually not a problem. Some chargers will drop the voltage a little under load, which also should not be a problem. The current that can be delivered is variable and depends on what the device needs and the charger can handle. Too heavy a charger does not matter, too light a charger only makes the device charge slower, but no technical problems should be caused. Now, I just yesterday received a new charger, and it has two ports, one for 1 amp of current, and one for 2.4. If the tablet is almost empty, it will try to draw about 1.7 Amps of current, and with the 2.4 amp charger, this will cause a drop from 5V to 4.7V. This also caused the touchscreen to lag. When I used the 1 amp port it could not charge as fast, but the voltage remained at 5 volt. Because of this the touchscreen did not lag. So basically, a charger that drops its voltage too much will make at least some touch screens of the nvidia SHIELD lag. the problem can be solved by taking a charger that does not drop its voltage under load, which in my experience means a less heavy charger then is needed for optimal charging. I recommend using two chargers, if you cannot find a heavy one that does not drop its voltage too much. Also, English is not my first language, so I apologize for any language issues.
Hello,

I have the SHIELD Tablet, and like many of us had problems with a laggy touchscreen when certain chargers were used. It only happened by some, but not by all.

Using a USB volt and current meter, I was able to identify the cause of the problem.

First some technical background. USB ports and chargers always should give 5 volt. Small variances are allowed, and usually not a problem. Some chargers will drop the voltage a little under load, which also should not be a problem. The current that can be delivered is variable and depends on what the device needs and the charger can handle. Too heavy a charger does not matter, too light a charger only makes the device charge slower, but no technical problems should be caused.

Now, I just yesterday received a new charger, and it has two ports, one for 1 amp of current, and one for 2.4. If the tablet is almost empty, it will try to draw about 1.7 Amps of current, and with the 2.4 amp charger, this will cause a drop from 5V to 4.7V. This also caused the touchscreen to lag.

When I used the 1 amp port it could not charge as fast, but the voltage remained at 5 volt. Because of this the touchscreen did not lag.

So basically, a charger that drops its voltage too much will make at least some touch screens of the nvidia SHIELD lag. the problem can be solved by taking a charger that does not drop its voltage under load, which in my experience means a less heavy charger then is needed for optimal charging. I recommend using two chargers, if you cannot find a heavy one that does not drop its voltage too much.

Also, English is not my first language, so I apologize for any language issues.

#1
Posted 02/26/2016 05:42 PM   
Thanks for the info. I've been having this issue when I use my phone's charger, which has quickcharge.
Thanks for the info. I've been having this issue when I use my phone's charger, which has quickcharge.

#2
Posted 02/28/2016 12:49 AM   
came here to post the issue, found the solution/cause thanks for the info!
came here to post the issue, found the solution/cause thanks for the info!

#3
Posted 02/28/2016 03:45 AM   
Wow... Second valuable post in shield tablet forum in a day, thank you rberg ( first one made par Red_Eagle_LXIX, page 30 in the official 4.0 feedback update thread ) This explains why I have no more slowdowns since my charger replacement for a new one ( AUKEY brand ).
Wow... Second valuable post in shield tablet forum in a day, thank you rberg ( first one made par Red_Eagle_LXIX, page 30 in the official 4.0 feedback update thread )

This explains why I have no more slowdowns since my charger replacement for a new one ( AUKEY brand ).

#4
Posted 02/28/2016 09:22 AM   
I get input lag with a charger that does not drop voltage under load. If I use any 500mA charger, I don't get input lag. I also don't get input lag if the tablet is plugged into a charger, but is charged. I also get less severe input lag with different cables than with others. Finally, I have the pen, and it doesn't suffer from input lag in any of the above scenarios. My guess is that the lag is actually decreased touch sensitivity, not lag. Further, since there are high current power supplies that do not cause it, and I've ruled out voltage issues, my guess is that capacitance in the charger is affecting the touch screen.
I get input lag with a charger that does not drop voltage under load.

If I use any 500mA charger, I don't get input lag.

I also don't get input lag if the tablet is plugged into a charger, but is charged.

I also get less severe input lag with different cables than with others.

Finally, I have the pen, and it doesn't suffer from input lag in any of the above scenarios.

My guess is that the lag is actually decreased touch sensitivity, not lag.

Further, since there are high current power supplies that do not cause it, and I've ruled out voltage issues, my guess is that capacitance in the charger is affecting the touch screen.

#5
Posted 02/29/2016 02:47 AM   
I get input lag with a charger that does not drop voltage under load. If I use any 500mA charger, I don't get input lag. I also don't get input lag if the tablet is plugged into a charger, but is charged. I also get less severe input lag with different cables than with others. Finally, I have the pen, and it doesn't suffer from input lag in any of the above scenarios. My guess is that the lag is actually decreased touch sensitivity, not lag. Further, since there are high current power supplies that do not cause it, and I've ruled out voltage issues, my guess is that capacitance in the charger is affecting the touch screen.
I get input lag with a charger that does not drop voltage under load.

If I use any 500mA charger, I don't get input lag.

I also don't get input lag if the tablet is plugged into a charger, but is charged.

I also get less severe input lag with different cables than with others.

Finally, I have the pen, and it doesn't suffer from input lag in any of the above scenarios.

My guess is that the lag is actually decreased touch sensitivity, not lag.

Further, since there are high current power supplies that do not cause it, and I've ruled out voltage issues, my guess is that capacitance in the charger is affecting the touch screen.

#6
Posted 02/29/2016 02:49 AM   
I´m not sure if its charger related, i had this problem, thought it was a faulty extension cable, after pulling the cables out and in the problem was gone. Then it started again some days later at another place with same type of charger which worked before, after a reboot it worked fine again. I think it´s an software issue.
I´m not sure if its charger related, i had this problem, thought it was a faulty extension cable, after pulling the cables out and in the problem was gone. Then it started again some days later at another place with same type of charger which worked before, after a reboot it worked fine again.
I think it´s an software issue.

#7
Posted 03/02/2016 12:47 PM   
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