# 2500mAh power babk for usb otg enough?



## yeahman45 (Oct 16, 2011)

2500mAh power babk for usb otg will last for how long .. say by connecting a usb sd card reader? (and you must take into account that it will charge the touchpad at the same time unfortunately).


----------



## Colchiro (Aug 26, 2011)

http://rootzwiki.com/topic/39111-recommend-me-an-external-battery-backupcharger/


----------



## yeahman45 (Oct 16, 2011)

thx how long would it last powering a usb pendrive while also charging (i guess this can't be stopped)?


----------



## jcsullins (Sep 27, 2011)

To disable charging, you can run this AFTER connecting the USB cable/device:


```
echo "off" > /sys/devices/platform/max8903b_chg.0/currentlimit
```


----------



## nevertells (Oct 29, 2011)

jcsullins said:


> To disable charging, you can run this AFTER connecting the USB cable/device:
> 
> 
> ```
> ...


from ADB or terminal emulator?


----------



## Colchiro (Aug 26, 2011)

I would try terminal.


----------



## yeahman45 (Oct 16, 2011)

jcsullins said:


> To disable charging, you can run this AFTER connecting the USB cable/device:
> 
> 
> ```
> ...


thx man i will try! can you create .bat equivalent file on android?


----------



## yeahman45 (Oct 16, 2011)

check this power bank with *an sd card reader* : http://www.pandawill.com/multifunctional-cager-b0301-portable-power-bank-with-double-led-lights-sd-card-slot-card-reader-p69381.html

would this mean no need to use a y-cable? just connect the powerbank to the touchpad and you can use the sd card reader directly


----------



## yeahman45 (Oct 16, 2011)

yeahman45 said:


> thx man i will try! can you create .bat equivalent file on android?


jus tred in terminal emulator, does not seem to work, it is still charging


----------



## jcsullins (Sep 27, 2011)

yeahman45 said:


> jus tred in terminal emulator, does not seem to work, it is still charging


Hmm, try this instead: (remember, must run it AFTER (wait at least a few seconds) you have plugged in USB cable)


```
<br />
echo "current0ma" > /sys/devices/platform/max8903b_chg.0/currentlimit<br />
```


----------



## nevertells (Oct 29, 2011)

jcsullins said:


> check this power bank with *an sd card reader* : http://www.pandawill...der-p69381.html
> 
> would this mean no need to use a y-cable? just connect the powerbank to the touchpad and you can use the sd card reader directly


Looking at the specs, it looks like this device uses an external power supply, so don't see how they can call it portable, unless they mean in your pocket. What most folks have been looking for is a usb hub that is powered by an internal battery and they will not work for long because the TouchPad pulls almost 2 amps when charging. J.C. Sullins is suggesting a temporary patch that would turn off charging so a battery powered usb hub should work.


----------



## yeahman45 (Oct 16, 2011)

nevertells said:


> Guess this means that one must do this via ADB not terminal emulator.
> 
> Looking at the specs, it looks like this device uses an external power supply, so don't see how they can call it portable, unless they mean in your pocket. What most folks have been looking for is a usb hub that is powered by an internal battery and they will not work for long because the TouchPad pulls almost 2 amps when charging. J.C. Sullins is suggesting a temporary patch that would turn off charging so a battery powered usb hub should work.


where does it say it need external power supply? it looks like a power bank with sd card reader! i have the usb battery powered hub and it last for a very short time.

thx for the commands Jcsullins, i will try it tonight. thx


----------



## nevertells (Oct 29, 2011)

yeahman45 said:


> where does it say it need external power supply? it looks like a power bank with sd card reader! i have the usb battery powered hub and it last for a very short time.
> 
> thx for the commands Jcsullins, i will try it tonight. thx


Look at the specifications:

*Specifications:*
Input voltage: DC5V--1A

That tells me that it needs to be plugged into a power source. And where else on the whole page does it say it has a battery in it? And if it does have one, it's not going to be much for $20

Here is a external backup battery one can use to charge usb chargeable devices and it's $85 bucks just for the battery.

http://www.bestbuy.com/site/Lenmar+-+PowerPort+Wave+6600+Lithium-Polymer+Battery+and+Charger/3386191.p?id=1218397307007&skuId=3386191&st=powerport&cp=1&lp=1&ci_src=11138&AID=10474050&PID=6146855&SID=m33amzsaxis&URL=http%3A%2F%2Fwww.bestbuy.com%2Fsite%2FLenmar%2B-%2BPowerPort%2BWave%2B6600%2BLithium-Polymer%2BBattery%2Band%2BCharger%2F3386191.p%3Fid%3D1218397307007%26skuId%3D3386191%26st%3Dpowerport%26cp%3D1%26lp%3D1%26ci_src%3D11138&ref=39&CJPID=6146855&loc=01#tab=overview


----------



## yeahman45 (Oct 16, 2011)

it says it's a portable power bank.... i assumed a power bank has a battery to charge your phone right? maybe i am misunderstanding it?

thought "Input voltage: DC5V--1A" is for charging the powerbank?


----------



## ndinfla (Aug 28, 2011)

yeahman45 said:


> it says it's a portable power bank.... i assumed a power bank has a battery to charge your phone right? maybe i am misunderstanding it?
> 
> thought "Input voltage: DC5V--1A" is for charging the powerbank?


From what i am reading it looks like it charges from a USB "Please charge the power bank with micro USB cable
Comes with 5 adapters, meet your needs" My reasoning for this is there is no other input on the box to use an external power source. 2500Mah is printed on the unit it self so i would assume it is a self powered unit.

Input voltage: DC5V--1A
Output voltage (1): DC5V--1A
Output voltage (2): DC5V--2.1A

Just looked at some of there other products seems they have one that is 12500Mah and supports up to 32 gb SD. Model B030.


----------



## yeahman45 (Oct 16, 2011)

ndinfla said:


> From what i am reading it looks like it charges from a USB "Please charge the power bank with micro USB cable
> Comes with 5 adapters, meet your needs" My reasoning for this is there is no other input on the box to use an external power source. 2500Mah is printed on the unit it self so i would assume it is a self powered unit.
> 
> Input voltage: DC5V--1A
> ...


yup but more expensive.. this one is the cheapest... maybe i will buy try this one to see if it works fine or if anyone already buying it can post a feedback.. i like the idea that having a builtin sd card reader... so maybe no need for an additional cable and external sd card reader; the card reader is probably powered by the builtin power bank right?


----------



## nevertells (Oct 29, 2011)

yeahman45 said:


> yup but more expensive.. this one is the cheapest... maybe i will buy try this one to see if it works fine or if anyone already buying it can post a feedback.. i like the idea that having a builtin sd card reader... so maybe no need for an additional cable and external sd card reader; the card reader is probably powered by the builtin power bank right?


Well, maybe it does have some kind of a battery in it. But common sense would tell one that for $20 it's not going to be much of one. I think that old saying of " You get what you pay for" applies.


----------



## Colchiro (Aug 26, 2011)

I ordered a two-pack of specialty hang-nail clippers shipped from China for $3.99.


----------



## nevertells (Oct 29, 2011)

Colchiro said:


> I ordered a two-pack of specialty hang-nail clippers shipped from China for $3.99.


You old kidder you!









I got mine last year for $.99 and it only took 6 months for drop ship.


----------



## Colchiro (Aug 26, 2011)

So dreams DO come true....









Hang in there yeahman45!


----------



## yeahman45 (Oct 16, 2011)

seems too big







i am searching for a more compact solution so that my touchpad remains portable with usb otg

check this one : http://www.ebay.com/itm/Technocel-UV9BB-Battery-Boost-Portable-Battery-Pack-with-USB-MicroSD-Card-Reader-/380442464161?pt=US_Memory_Card_Readers_Adapters&hash=item5894234fa1

how long do you think it will last as a self battery powered sd card reader once fully charged?


----------



## nevertells (Oct 29, 2011)

yeahman45 said:


> seems too big
> 
> 
> 
> ...


It has a 600mA battery in it. Unless you can turn off the charging circuits in the TouchPad, it will be drained in a couple of minutes.

Did anyone ever verify the code J.C. Sullins posted to shut off the charging in the TouchPad?

Just using it to power a micro SD card, it should last for a while. Anyone know how much current a micro SD card pulls?


----------



## Gradular (Feb 1, 2012)

nevertells said:


> Look at the specifications:
> 
> *Specifications:*
> Input voltage: DC5V--1A
> ...


 i recommend this one. I've been using it for portable org and charging for all my devices, including my Touchpad.

Sent from my SPH-M930BST using RootzWiki


----------



## Colchiro (Aug 26, 2011)

I like thi


Gradular said:


> i recommend this one. I've been using it for portable org and charging for all my devices, including my Touchpad.
> 
> Sent from my SPH-M930BST using RootzWiki


Not a fan of the overpriced Best Buy. You can buy it on Amazon for half the price: http://www.amazon.com/gp/product/B005DTJI7Y?linkCode=xm2&tag=invihand-20


----------



## yeahman45 (Oct 16, 2011)

jcsullins said:


> Hmm, try this instead: (remember, must run it AFTER (wait at least a few seconds) you have plugged in USB cable)
> 
> 
> ```
> ...


unfortunately this does not work







anyway got it working?


----------



## jcsullins (Sep 27, 2011)

yeahman45 said:


> unfortunately this does not work
> 
> 
> 
> ...


Could you elaborate? More details?


----------



## yeahman45 (Oct 16, 2011)

jcsullins said:


> Could you elaborate? More details?


i executed the command in terminal emulator with su permissions .. got no error/message but the touchpad was still charging


----------



## jcsullins (Sep 27, 2011)

yeahman45 said:


> i executed the command in terminal emulator with su permissions .. got no error/message but the touchpad was still charging


OK, I have a simple app that you can use to help diagnose:

http://goo.im/devs/jcsullins/cmtouchpad/apps/TPChargeTest-v1.0.apk

Connect your USB battery pack thing and run TPChargeTest -- what are the CurrentLimit and CurrentNow readings?

Then run the 'magic command' from above and wait 1 min -- what are the CurrentLimit and CurrentNow readings now?


----------



## yeahman45 (Oct 16, 2011)

thx for replying and helping... i tried yesterday but it seems that the touchpad does not charge when battery level is green lol... it was not charging when connected to be battery powered usb host... will try to discharge the touchpad a bit more before trying it ... anyway, without running the command, the currentlimit was none and currentnow varied a lot...


----------



## yeahman45 (Oct 16, 2011)

ok here are the results of my test:

*before applying command:*

CurrentLimit : None
CurrentNow: -530000 to - 640000 (it varies)
Capacity : 70

*after applying command after 1min:*
CurrentLimit : current0ma
CurrentNow: -381406 to -539218 (varies also)
Capacity : 70

still having battery icon in charging mode


----------

