how to charge the W4 820 tablet while data transfer is going on with usb ?

arijitbanerjee

I have W4 820 tablet, is it possible to charge the device at the same time do the data transfer using the USB port ?

padgett

Since I don't have a W4, I don't know but a similar Bay Trail tab (that had GPS) just needed a special three head cable. Tab said "plugged in, not charging" and while it did not charge, it did not lose any charge either, if it started with 88% after 10 hours on a docking station it still had 88%.

arijitbanerjee

will you please elaborate the type & name of the three head cable ?

padgett

I use a StarTech 3-Feet USB Y Cable Dual USB A to Micro B (USB2HAUBY3)

(http://www.amazon.com/gp/product/B0047AALS0/). The red plug goes in the power source, micro in my tablet, and the black USB to my docking station.

 

Since I do not have a W4 I cannot promise it will work there but should.

 

It does not add to the charge level but keeps it at the same level as you started. I've been using one since last year.

 

Acer should be selling accessories like this.

arijitbanerjee

thanks, i shall try that.

FerryAnoid

Will you please post back on this and the W4 as I am about to buy a W4-64gb. My Lenovo Miix (sending it back) will actually charge using one ofthe 3-head cables and passing USB data. The Dell Venue Pro would do neither, nor the ASUS Vivo tab.

 

Not lowering the charge would be OK, but being able to charge with USB data use, is even better.

 

 I am using one of these with the Lenovo, not the one shown above...

 

http://www.amazon.com/gp/product/B00EJP5XR2

 

 

padgett

That is an OTG cable and I was never able to get one of those to work but then i do not have a W4 so do not know.

 

This is what I get with the one I mentioned connected to a Targus Docking station with keyboard, mouse, DVD, terabyte drive and 24" monitor.

 

Plastixx

The W4 needs the data lines tied together to initiate charging. I also believe that the tablet might check for a specific voltage level, which is why the included power supply is rated at 5.35V.

 

And completely off topic, but I justed wanted to mention I succesfully installed the latest Intel HD 4000 graphics driver (manually via device manager). It installed without any problems and CS:GO plays MUCH smoother now.

padgett

Agree, to have it charging they do. However on my tab it is possible use the Y cable I mentioned to go into a "Plugged In, Not Charging" state where the tab is running on mains power and not using the battery. If you begin with 88%, 12 hours later you will still be at 88%.

 

Then when work is done you can switch to a charging cable while the tab is not using the USB line and return to 100%.

billsey

I've been reading a bit more on the charging circuits used on these newer devices and think i understand a bit about what is happening...

 

The USB charging circuit has the two USB data pins either shorted together or bridged with a resistor (the latter is for Apple devices). When the charging circuit in your tablet or phone sees that state on the USB port it knows there's a charger connected and it can draw full current for charging.

 

The USB data circuit has actual data causing voltage fluxuations between the two data pins. When the charging circuit on your tablet or phone sees that state is minimizes the amount of draw from the power in order to not break whatever has been plugged in. Remember most USB devices you might plug in actually take power from the port rather than providing power to the port.

 

The simplest thing, design wise, for an engineer to do is charge when a charger is plugged in and not charge when a different device is plugged in. Luckily the engineers at Acer (and elsewhere) have chosen instead to provide active circuits that allow charging at minimal levels off non-charging connections. This is why we see the tablet holding a charge when connected to a charging/data device and only going into fast charge mode when a charger is connected.

 

I tested this a bit this afternoon on my Samsung Galaxy S5 phone. If I connected a charger (shorted between data pins) it went into fast charge mode and charged at the rate the charger could provide (tested with a 2A, a 800mA and a 500mA charger, they ranged from 25% to 50% increase in charge over a half hour). When I connected either a data cable from my PC or an old microUSB charger (280mA) that didn't have the data pins shorted it charged at the slow rate (doing a little better than break even, it took about a half an hour to climb 1%.

hkstiong

Hi Billsey

---

billsey wrote:

 

 

The simplest thing, design wise, for an engineer to do is charge when a charger is plugged in and not charge when a different device is plugged in. Luckily the engineers at Acer (and elsewhere) have chosen instead to provide active circuits that allow charging at minimal levels off non-charging connections. This is why we see the tablet holding a charge when connected to a charging/data device and only going into fast charge mode when a charger is connected.

 

---

Your writeup means the OTG/docking connectors sold at Amazon (mentioned earlier in the thread) will allow use of the USB while maintaining charge (if not charging). 

 

Thanks

 

 

billsey

Needless to say I can't guarantee that all of the OTG splitters on Amazon will work, but at least we know that some will, and likely most will. If you stick with the ones that have been suggested by people who have seen it work on theirs you are probably OK. And if you pick up a different one that also works, link it here!

mojojojo

I was browsing different threads when I came across this interesting post:

 

http://forums.wpcentral.com/upcoming-rumored-tablets/262359-thinkpad-8-may-not-charge-while-docked-via-usb.html#post2676148

 

According to the item descriptions from Taobao and Pabbos (poorly translated from taobao), there is a generic version for several tablets and an Acer W4-820 specfic one.

 

Just bought the Acer specific one from Pabbos. Will wait for it to arrive and update if it works.

arijitbanerjee

Thanks for your information, I already purchased one & waiting for delivery. Thanks again.

padgett

The problem is twofold:

1) The charge/data issue must be handled by the BIOS

2) No-one seems to follow the MS specification ( see http://msdn.microsoft.com/en-us/library/windows/hardware/dn481329(v=vs.85).aspx and the references.

 

As a consequence some will work one way, some will work another. Frankly I think having just one USB connector for both charging and data transfer is somewhat dim.

 

That said, my Bay Trail Tab works as I described using the Startech Y cable and that is Good Enough. Be aware that any charger ised must be capable of at least 1.5A at 5v to function properly (I use a 3.1A cigarette lighter adapter in the car and a Targus Docking station with a 6.5A supply at home).

 

SteveR1

Mojojojo and arijitbanerjee,

 

Please please write up your experiences with the cable you ordered from Pabbos. It looks good from the link in that it has a picture of the Acer W4 charging with USB hub and devices attached! The English translation doesn't make too much sense but I believe that it is talking about a specific sequence you need to plug in the ports and chargers. We should be able to figure that out and post here in clear instructions.

 

This could be a game changer for this tablet if it works reliably, even if it's a bit fussy about plug in sequence. Even a slow charge or maintain charge would be fine.

 

Anyone who hasn't clicked the Pabbos link should have a look - this cable has a built in 4 port USB hub with micro USB male at one end for tablet and full USB male at the other end for charger. Noted as working for Acer W4 (scroll further down) and also many mobile phones (eg Galaxies), so this could have multi uses for some purchasers. It has a 3 position switch to support the needs of different devices, presumably linked to shorted wires etc.

 

Thanks.

Steve.

arijitbanerjee

 

 

Today I got the Y cable, tested, but it is not working. If I put the red cable to the charging station & black cable to the USB HUB then the tablet is not showing any USB device connected to the HUB & it is not showing charging also. If I connect black end to charging station & red end to USB HUB then the tablet is showing charging but not connected to any device of the USB HUB.

hkb

Anyone try this charging and data dongle from Dell yet?

 

http://accessories.dell.com/sna/productdetail.aspx?c=us&l=en&s=dhs&cs=19&sku=470-ABES

Plastixx

I really don't think anything will work. The tablet simply wasn't designed in a way to allow charging and USB host mode at the same time. I could be wrong, but we are talking about Acer here.

billsey

What we have found is that you can *maintain* a charge with one of the splitters, you can't bring a charge up though. If you start fully or mostly charged you could potentially cycle through your entire music library in one session...

arijitbanerjee

 

The product from Pabbos I just got in my hand. It works perfectly, thanks for the help.