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USB Question
 

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Andy M-S
Joined: 11 Jan 2004
Posts: 3377
Location: Hamden (greater New Haven) CT

11/6/13 8:15 AM

USB Question

I'm asking because people here like to mess about with their stuff, so...

1. I have a phone dock I like. It has one USB connector.
2. I would like to leave my phone in it to charge overnight, AND
3. Have it connected to my PC BUT
4. When the PC is sleeping, its USB port power is off
5. I can use a wall wart charger plugged into the dock BUT
6. then the phone isn't connected to the PC

I want to have it all. Is it electrically feasible to have BOTH a charger and a signal cable to my PC plugged into the same port (assume it's physically feasible) or do I risk toasting my computer and/or phone by doing so?

I could wire up the necessary cable without too much trouble. The question really is, am I putting my equipment at risk by doing so? I suppose one solution would be to have the cable going to the PC carrying data only (i.e., disconnect the power-carrying lines in that cable). Then I'd only have to worry about all the grounds floating around, but that's an issue with USB and multiple devices anyway.

Thoughts?

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

11/6/13 8:46 AM

How about making the PC non-sleeping?

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Andy M-S
Joined: 11 Jan 2004
Posts: 3377
Location: Hamden (greater New Haven) CT

11/6/13 8:53 AM

To sleep, perchance to dream

I've thought about that, but I kind of like knowing the machine is offline some of the time. Silly, really, because it doesn't use that much power and it's reasonably secured. But I suppose as long as it's not using the battery, that could be a reasonable way to proceed.

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walter
Joined: 11 Jan 2004
Posts: 4391
Location: metro-motown-area

11/6/13 11:11 AM

some laptops have a...

...continuously powered USB port that stays hot even when the machine is in sleep mode (maybe even when off). it's very motherboard/bios specific capability, though.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

11/6/13 11:23 AM

I think it is not good for the battery in the phone to be getting charged after it is charged, assuming Lithium.

Wouldn't keeping it plugged in and the port hot all the time basically make your battery in the phone have a shorter life? Unless I have mis-information...

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

11/6/13 11:58 AM


quote:
some laptops have a...
...continuously powered USB port that stays hot even when the machine is in sleep mode (maybe even when off). it's very motherboard/bios specific capability, though.


Yep! I have two laptop and one kind of of each!

My newer laptop has a fairly extensive power management option which I can set it to never sleep when plugged in but sleep after x minutes of inacitivity when on battery.

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

11/6/13 12:30 PM

You can have it all.

Is the computer hibernating or on stand-by? IOW, can you wake it up with a keystroke or do you need to press power? That one change might be enough. Hibernating writes memory to disk, stand-by leaves memory charged but the rest of the system is off.

For your idea, look for a usb cable made for an external drive if you want to attempt the multi-source approach. You can make one too. They are like you imagine: one A end is power/data the other A is power only, and the B end is... the B end. A hard-wired wall charger will not work with a cable like that, you will need one with a USB-A female.

I use one that's plugged into two 1A transformers and it charges my smartphone, a kindle and a picky Sansa Clip mp3 faster than a single 1A. 2A of 5v power. That said, a little dumbphone refused to take a charge from the setup but when I put it back on a 700mA it did just fine.

Building it yourself might work out better since the pre-made ones usually just have a short pigtail between the two A ends.

Make sure your USB charger has enough amperage to charge your phone. Take a hard look at the specs printed on the one you use and look for output volts and amps. Any charger almost certainly will be enough, but the Sansa example above is one that, for some reason, requires a full amp to charge. The device is the size of a couple of postage stamps but insists on a lot of power to charge. I also have a car charger/FM-mp3 deal that doesn't put out enough amps to charge a phone. All is does is keep it from dying as fast.

You might try a powered USB hub, but amperage can be a problem there too. The couple I tried wouldn't charge the Sansa.

As for leaving it in after it seems fully charged, I'm all for it. Sometimes those indicators are not accurate and experience indicates it's not bad for the battery. That said, I try to run the battery down until it's desperate before I recharge it.

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Andy M-S
Joined: 11 Jan 2004
Posts: 3377
Location: Hamden (greater New Haven) CT

11/6/13 12:48 PM

A collective reply, in no particular order.


quote:
You might try a powered USB hub, but amperage can be a problem there too. The couple I tried wouldn't charge the Sansa.


Yeah, tried that. Unfortunately, it turns out that the powered hub that I have ALSO switches power off to the downstream ports when the upstream port to which it is connected powers down.

Now, as it turns out, I do have a yellow "powered sleep" USB port, but I think I turned that off in the BIOS, so turning it back on would likely work and solve all of my problems. The machine is a little Lenovo Thinkpad.

Definitely using sleep mode. I installed an SSD, so hibernation would be fine, but waking up from sleep is just a little faster, and I like it.

As for charging--most phones are smart enough to handle the charging side these days; they don't rely on the charger/USB port to do that for them. In my experience, leaving a phone plugged in for long periods will do little or nothing to irritate the battery, just as is the case with modern laptops. Thank goodness.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

11/6/13 12:54 PM

My phone charges totally via USB, it just takes a long time as compared to the little AC plug box with the USB port on it I use as the main charger. Which is cold when the phone is not plugged in and warm when it is. Even when the phone is fully charged, in fact warmer then... Deduce what you may from that, but I figure warm is using more juice plain and simple, no?

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

11/6/13 1:03 PM

I think so too.

It appears keeping it topped off after a deep cycle is not as bad as consistently charging back up it when it still has some significant charge left (hard to say what the cutoff is, 50%? 35%?)

But I've had devices that read "full" but it was obvious if they were unplugged immediately and used normally that they weren't crammed full. They may meet spec, but not capacity.

Maybe you could use one of the Y cables ;-)

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Andy M-S
Joined: 11 Jan 2004
Posts: 3377
Location: Hamden (greater New Haven) CT

11/6/13 1:18 PM

Hmm.


quote:
But I've had devices that read "full" but it was obvious if they were unplugged immediately and used normally that they weren't crammed full. They may meet spec, but not capacity.


That has not been my experience with USB-charged devices (my LG and Nokia phones and my Kindle Paperwhite) but that's not to say that it couldn't happen with some.

And yeah, I expect that warm is using more juice. Again, it hasn't been my experience with my phone (or notebook). When I got the notebook a couple of years ago, it ran ~ 5 hours on a charge, and it's still pretty close to that. Way better than the 15 minutes some batteries would drop to in the old days!

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

11/6/13 1:34 PM

"notebook a couple of years ago, it ran ~ 5 hours on a charge, and it's still pretty close to that."


This Lenovo I have for a year is falling off way slower than any lap/note previously. Better Lithium tech? and definitely power mngmnt in the firmware I figure.

Elaine is using the ASUS, my previous for her main, and it might as well not have a battery in it. ;)


Last edited by Sparky on 11/6/13 1:58 PM; edited 1 time in total

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

11/6/13 1:48 PM


quote:
(my LG and Nokia phones and my Kindle Paperwhite)
That probably says something for the high quality of the devices too.

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Andy M-S
Joined: 11 Jan 2004
Posts: 3377
Location: Hamden (greater New Haven) CT

11/6/13 3:52 PM

Hardware


quote:
That probably says something for the high quality of the devices too.


Life's too short for cheap hardware. If you're willing to wait a few minutes after the latest drops, either the latest or the latest-1 will be cheap. I got my X120e for less than half the "street" price less than a year after it was released. I expect to use it for quite a while yet.

That being said, my spouse is still happily working on a 3-year-old Acer Netbook, and the battery on that machine is still doing well, too. I think that speaks to just how greatly improved technology is today. When I think of my first laptop...!

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Steve B.
Joined: 19 Jan 2004
Posts: 769
Location: Long Island, NY

11/6/13 6:00 PM

Just curious, why is the phone hard wired to the PC ?.

Could you Bluetooth pair the phone to the PC for data transfer ?, which then allows the phone to use one USB charge cable ?.

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ErikS
Joined: 19 May 2005
Posts: 8337
Location: Slowing boiling over in the steamy south, Global Warming is real

11/6/13 7:44 PM

Yeah why only to the PC.

Most current phone chargers are smart and know how to care for their paired battery. Apple chargers are very smart and the best things to charge your apple devices.

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