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Sachin Naik

join:2008-12-08
India

[Parts Check] Connecting 2 cellphones to a computer

I had connected two mobile phones to my computer via the USB ports and suddenly all the tubelights even of my other room started blinking and my UPS started switching between power & battery mode randomly. I kept them connected for about 1 minute thinking that it is an electricity glitch and then I directly turned OFF my UPS as i was scared and then none of my tubelights were blinking everything became normal.

So the question is is it hazardous to connect 2 cellphones to the PC via USB ports. Has anyone tried it?. Of course both the phones were charging through USB as you can't disable their charging.

I have to update my mobile firmware that's the reason i have to connect them together.



DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
kudos:2

Not hazardous, but not a great idea, as the two phones are drawing more current through the laptop than it can handle. That's why the UPS is going crazy. You also risk damaging the charging circuit on the phone and the laptop. Just do it one at a time. Or charge one from the wall outlet and one from the laptop and then switch them.
--
Need-based health care not greed-based health care.



Sachin Naik

join:2008-12-08
India

Not laptop it's a computer. Now i was thinking of connecting one phone at the front side USB port and the second phone at the back. Will that be okay?. Earlier i had connected both the phones on the front USB ports.

I need to connect both my phones together to update one of its android version. There is no other option actually. But if it's dangerous then I can stop and go for an alternative.

Please assist me. There is no information available on the Internet. I searched it everywhere.

Thanks in advance



Octavean
Premium,MVM
join:2001-03-31
New York, NY
kudos:1
reply to Sachin Naik

I'm sorry I guess I don't quite understand.

You cited a firmware upgrade and then cited an Android version upgrade. I take these to be two different things and I am not clear on why both phones need to be connected simultaneously. In fact, if I wanted to upgrade the firmware or OS of a phone I would prefer that there weren't any other devices connected as this would simplify maters IMO. So I would do one phone at a time in succession.


HappyFrappy

join:2000-10-04
North
reply to Sachin Naik

Every phone maker makes it clear you're supposed to firmware update one phone at a time...

Unless the PC has a rapid charge supported port(s) you'll risk frying the port/motherboard header when plugging in two smartphones as they draw more bus power than a dumb phone. My old Motorola Photon 4G(Android) usually needed to be plugged into a powered hub when syncing with Outlook/copying files/documents, if I used a front port with >50% battery remaining an error from Windows Vista would popup "Your usb mass storage device can perform faster if it is plugged into a hi-speed port". Some mobos have the safety feature to drop down to a lower speed but some don't and port failures occur.

...if you hit the power limit, use a powered hub as burning out a USB port ain't fun (had it happen on a notebook)



Octavean
Premium,MVM
join:2001-03-31
New York, NY
kudos:1
reply to Sachin Naik

I was going to suggest a powered USB hub as well but just couldn't quite get past why the OP seems to think it is necessary to connect both phones at the same time.



Sachin Naik

join:2008-12-08
India
reply to Octavean

said by Octavean:

I am not clear on why both phones need to be connected simultaneously.

It's actually a Kitkat android update for my Sony Xperia. But to do that i need to turn off 3G of my Xperia phone or else it won't communicate with my PC suite therefore i need another phone for Internet connection as i don't have ADSL line. My friends don't have Internet either.

Well I just had to post this for u to know why i wanted to connect 2 phones to my computer.

I want to know whether i will blow up something. Is it safe?. Any kind of help is appreciated.

dave
Premium,MVM
join:2000-05-04
not in ohio
kudos:8
Reviews:
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reply to HappyFrappy

said by HappyFrappy:

Unless the PC has a rapid charge supported port(s) you'll risk frying the port/motherboard header when plugging in two smartphones as they draw more bus power than a dumb phone.

I understand the distinction between ports rated for 'normal USB devices' and ports rated for charging.... but don't they build current limiters into these things?

I thought that, if nothing else, the port is supposed to indicate whether it can supply the higher current, and the device isn't supposed to ask for it unless it's supported.


DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
kudos:2
reply to Sachin Naik

said by Sachin Naik:

said by Octavean:

I am not clear on why both phones need to be connected simultaneously.

It's actually a Kitkat android update for my Sony Xperia. But to do that i need to turn off 3G of my Xperia phone or else it won't communicate with my PC suite therefore i need another phone for Internet connection as i don't have ADSL line. My friends don't have Internet either.

It's not recommended that you upgrade firmware wirelessly.
--
Need-based health care not greed-based health care.


Sachin Naik

join:2008-12-08
India

said by DKS:

It's not recommended that you upgrade firmware wirelessly.

Oh no i am sad to hear this. Now i am deciding to buy a 3G dongle. Is that ok for the update. Our cybercafes here are poor and they use outdated computers. So there's nothing i can do besides a wireless dongle. Is that ok?


DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
kudos:2

You could try running one cell phone off a regular electrical outlet through a regular power adapter and turning the personal hotspot on. Use wifi to connect the laptop to the cell phone hotspot and then connect the other phone to the laptop. Reverse the phones when one is updated. Be aware that any power interruption or signal loss can turn your cell phone you are updating into an expensive brick.
--
Need-based health care not greed-based health care.



beststoryeva

@69.118.94.x
reply to Sachin Naik

said by Sachin Naik:

I had connected two mobile phones to my computer via the USB ports and suddenly all the tubelights even of my other room started blinking and my UPS started switching between power & battery mode randomly. I kept them connected for about 1 minute thinking that it is an electricity glitch and then I directly turned OFF my UPS as i was scared and then none of my tubelights were blinking everything became normal.

So the question is is it hazardous to connect 2 cellphones to the PC via USB ports. Has anyone tried it?. Of course both the phones were charging through USB as you can't disable their charging.

I have to update my mobile firmware that's the reason i have to connect them together.

So you are trying to say here, connecting two phones to the computer caused all these weird power problems? I mean really?

Just tether one phone if you need internet access it is never recommended to have anything other than the drive you want to do critical work on (like this, format hdd, etc) connected...

I would download whatever you wanted to update... not sure how you NEED internet to do the update... download, save, update offline...

Okay, nextly, LOL @ drawing too much current.

First off, USB2 is 500ma... phone is gona draw what, ignoring the fact that usb is limited and can't draw too much power... 750ma? 1000ma (could be more idc)? So okay we got two phones @ 2000ma 5v vs 1000ma 5v

That is really going to overload the UPS? So explain please, what is happening to the laptops power brick... that thing should have no issue outputting enough power, we are talking about using dick vs running up the CPU or GPU.

Speed has nothing to do with power...

Now let's just run with this, 2 phones, 2000ma... draw

Let's bring in an Ipad.

Oh gosh, every pc everywhere would be burned out the second you plugged in one of those things... 2.1 amp draw...

Ever plug on into a PC USB... Oh rite, screen on, it won't charge (pesky usb only putting out 500ma when it wants 2.1a) and will charge SLOW when screen is off.

Exactly what is going on with the phones... they are getting 500ma...

No magical overload is occurring...


DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
kudos:2

said by beststoryeva :

Exactly what is going on with the phones... they are getting 500ma...

No magical overload is occurring...

OP is posting from India... 230V 50hz.
--
Need-based health care not greed-based health care.


Sachin Naik

join:2008-12-08
India
reply to DKS

said by DKS:

Use wifi to connect the laptop to the cell phone hotspot and then connect the other phone to the laptop.

The funny thing is that the other phone is just a basic phone which doesn't support 3G and hotspot so i was trying to update my Xperia using 2G network of my other phone. So now i have changed my decision i am thinking of getting a 3G dongle to update my Xperia phone. So both the dongle and the phone to be updated will be connected to the PC. Isn't that okay?

Also note i am using a computer not a laptop.

dave
Premium,MVM
join:2000-05-04
not in ohio
kudos:8
reply to DKS

said by DKS:

OP is posting from India... 230V 50hz.

Not out of a USB socket... !

pandora
Premium
join:2001-06-01
Outland
kudos:2
Reviews:
·ooma
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reply to Sachin Naik

This may happen once in a while, particularly during hot summer nights.

See -

»www.youtube.com/watch?v=ghFBvBmXv4E

--
Congress could mess up a one piece jigsaw puzzle.


DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
kudos:2
reply to dave

said by dave:

said by DKS:

OP is posting from India... 230V 50hz.

Not out of a USB socket... !

I suspect a poor or flaky power supply.
--
Need-based health care not greed-based health care.

HappyFrappy

join:2000-10-04
North
reply to dave

The OP hasn't said the specs of the PC or PSU rating, however if a UPS is tripped there are other odds the local power isn't stable too.

said by dave:

I understand the distinction between ports rated for 'normal USB devices' and ports rated for charging.... but don't they build current limiters into these things?

I thought that, if nothing else, the port is supposed to indicate whether it can supply the higher current, and the device isn't supposed to ask for it unless it's supported.

Many "high quality/military spec or Intel Classic boards" have limiters on the board itself which act like a circuit breaker until reboot if it gets tripped, however lower cost motherboard makers/consumer pre-built PCs expect users to use a hub/powered hub instead of risking the port itself so frying a USB port is quite common(static discharge is up there if the case maker skimped on grounding). My old PowerBook G4 had a port blow & took out the built-in bluetooth on the shared bus, thankfully I had AppleCare and it made me more careful.

Charging ports will function like a normal USB 2.0 port, if the cable & device supports "rapid charge"(Garmin/TomTom GPS, OEM cables for phones/tablets, etc) it'll output the power then drop back to normal USB power at 95-100%. Downside is sometimes the port is incompatible with a small amount of USB devices so some PC makers just call it a "charge only port"(and/or remove the data support via BIOS) and have a footnote in the user manual PDF about it.


Sachin Naik

join:2008-12-08
India
reply to Sachin Naik

Thanks everyone for the feedback finally I have upgraded. The update just now was available on my phone itself. I had to wait. The reason why I was worried is because the notification said the upgrade is available only via PC. The Sony cc also told me the same that i can't upgrade it using my phone.



printscreen

join:2003-11-01
Juana Diaz, PR
Reviews:
·Choice Cable TV
·Coqui/PRTC
reply to Sachin Naik

I don't get it how connecting two cell phones to a computer can cause anything like that. A phone cannot draw anything more than what the port puts out. The worst that can happen is slow charge (or the phone refusing to charge at all). It is a small DC load, and not like a large AC inductive device such as a motor or large transformer that WILL overload a circuit if not provided enough juice. A typical PC power supply can handle plenty of small loads like that and you would not get even close to overloading a UPS in the process. The processor, hard drives and video card are much larger loads. I suspect something else happened there.

By the way, I *have* connected to cell phones to my computer at least once and nothing happened.

Inside the PC (the DC side of the power supply), my PC here it home is not different from the OP's PC in India.



Sachin Naik

join:2008-12-08
India

1 edit

@printscreen
Thanks a lot for making me aware of this. Your answer was straightforward. I knew it but the only reason why I went blank is because of the power fluctuation which started and then ended as soon as i switched OFF my UPS. But i don't know why some people are negative to this idea (including me hehehe). Anyways I don't need to connect them right now but i may need in future.