I just don’t understand this technology stuff

So, phone, USB to micro USB cable, phone connects to laptop. Android.

So, USB connection includes power, right? So why in buggery won’t phone charge from laptop USB?

Anyone? Bueller?

26 comments on “I just don’t understand this technology stuff

  1. I think… it’s because the setup is such that it’s the laptop expects to be /receiving/ power from the USB connection, not sending it out. Power-over-USB is a way of charging portable devices from a power source, the laptop is the “portable device” in this case so is expecting to be sucking in juice, not sending it out.

  2. Try a different port, then a different cable and finally the USB mode in settings on the phone.

    Not all ports output power, not all cables are wired for power, and occasionally Android phones default to MTP mode when connected to a laptop, and this doesn’t always charge the phone. In the USB settings menu, there is often a ‘Charge Only’ mode

  3. “So, USB connection includes power, right? So why in buggery won’t phone charge from laptop USB?”

    Um…just in case…..is your laptop plugged in to a power source?

  4. What John S says. If the phone is Android, go to settings > general > PC connection > USB connection and then tick Ask upon connecting – or perhaps there’s a ‘charge only’ option.

  5. “Bueller”? I dread to think what your Americanisms are doing to dearieme’s blood pressure…

  6. Assuming that you have a USB cable that passes power (USB is a 4 wire system, 2 power, 2 data – they may not both be in your cable):

    USB charging is very sensitive to the voltage and current supplied by the power source. It is supposed to be between 4.75v and 5.25v and in many cases there is a minimum current that the power source must be able to supply in order to make the device charge.

    Many USB sockets may limit the current supplied to less than that required by your device. Alternatively your device may be trying to draw such a high current that the internal resistance of the power supply causes the voltage output seen by your device drops below 4.75v (or whatever level your device needs).

    All this explains why many devices require particular chargers.

  7. I had the same problem with mine

    Try installing the driver for the mobile onto the laptop. Don’t know why that works, but it did for me.

    The driver will let you do all sorts of other stuff as well (manage the phone book, copy messages & pictures, etc.), but you can ignore all of that; for some reason it’s also needed to charge it up from the laptop (or at least it was with mine).

  8. (Mind you, my phone is an original Motorola Razr and my laptop runs on XP, so it might not work if you have more modern kit)

  9. You need to attach the cable to a tower during a lightning storm while shouting “live, damn you, live!”. Suck in your cheeks and try to look like Peter Cushing. Resurrection guaranteed.

  10. You can charge a phone off a laptop battery, it doesn’t need to be plugged in.

    It only won’t work for the same reasons as mentioned – if the current or voltage is insufficient

  11. Per Alex’s comment, a PC’s USB port will only pump out 0.5 amps; your Android phone might need at least 1.0 amp to charge.

    More likely, the PC doesn’t output power over USB if it isn’t plugged into the mains itself. There’ll be a BIOS option to change that; it might be accessible in Windows too, but I’ve lost track of where stuff is since Win8.

  12. Just buy a decent powerbank. Not expensive and worth it. My Ravpower has served me proud out on the road.

  13. Easier just to get a portable power pack. I wouldn’t even bother trying to charge a phone from a laptop or vice versa. With one charge I can recharge both my phone, my camera and tablet from the power pack

  14. Every USB port has to be able to supply some power (that little LED on your flash drive isn’t drawing power out of the aether!) but the amount it can or will supply may well be limited, or the phone might not be able to work out what is available and be shutting down charging at its end just to be safe. Depending on the configuration of both devices, how they implement the USB spec, the low level phone programming, and so on, it’s entirely possible you are simply shit out of luck 🙂 Playing with settings might help, but even if you can get it to work, charging will probably be really, really slow.

    Phones/tablets want to draw massive amounts of power compared to the original intent of USB, which was just to combine power and data for peripherals. A unit load (one low powered device, e.g. mouse, keyboard, flash drive) was originally set at 100mA, which really isn’t going to help what is effectively a computer with a 5″ screen very much. Devices are supposed to connect at this power then negotiate for more if it’s available. My guess is negotiations are breaking down 🙂

    USB wasn’t really designed for charging in the first place. It’s been tacked on for the usual reason – it was convenient and available, so “please sir, can I have some more?” applied. But it means that what can or can’t charge is very device dependent.

  15. I use my Sprout charger most of the time, but when using it a as a modem, I do charge my iPhone without any problems from an HP and an ASUS laptop without any issues, even when they are on battery power. Can charge iPads too. Didn’t have to change settings. In fact ASUS has a thing called ‘quick charge’ which it activates automatically when a portable device is detected.

  16. Some of those above have it, the answer is quite simple, most laptop’s won’t put out a high enough current to charge phones those this does vary by laptop and phone to some extent.

    Phones charge once there is a certain minimum current, and up to a point charge faster the higher the current. If you have a tablet charger that typically is a higher current unit and will charge your phone quicker. For example an iPad charger is larger and puts out more current than a standard iPhone charger, and thus charges an iPhone quicker. And a standard iPhone charger will barely charge an iPad at all. Nor for that matter will a laptop typically.

    Answer, use a wall plug charger, and if out of reach of one of those for a while carry a battery pack/charger – even a smallish one will provide two reasonable recharges.

  17. Tim A had it – change which USB port I was using. as to this idea, there is no “general” bit in “settings” which makes that a bit hard….

  18. Firewire was a far superior port for this sort of thing. Such a shame it didn’t take off.

  19. Isn’t this due to the wankery that is the USB micro interface? It either provides a recharge power supply or a data connection. But not both simultaneously. Connect to a laptop & it defaults to passing data.
    But the power available, too. My Windows* fone comes with a 750mA USB3 charger. It doesn’t seem to want to know a USB1 supply & complains bitterly at USB2

    *Yes I know. But the Android/Google option is such an horrendous piece of intrusive shite, if I must have one of these children’s toys… Please, please you Linux people. Get your fone distro up & working.

  20. Generally, a phone will be charged in that kind of setup. But if the laptop’s USB port is not able to supply enough current, the phone will not be charging its battery though it still could use the current for operation.

    Older laptop USB ports typically output 500 mA (required by the standard), not more, and your phone might require 1000 mA or more to actually be charged. Your laptop could have several ports which only supply 500 mA and one “charging port” that provides more. USB3 ports must be able to supply at least 900 mA but could supply up to 1500 mA which is enough for most phones and some tablets.

  21. Yeah, try a different port. The makers are not making them all the same, and you probably were not paying attention way back when.

    If it makes you feel any better, my Kindle would only charge with my new PC: no ebook management possible. After about 3 years, the front USB ports were plugged up, and I needed a quick charge for my Kindle. I plugged it in the back, and got complete functionality between Kindle and PC.

  22. There are many different sorts of USB port in power terms (Low-power, Low-power superspeed, High-power, High-power superspeed, battery charging, Type-C, Power delivery micro-format, Power delivery standard format, Power delivery Type C). Each one provides different levels of power, and low-power ports only provide minimal current (i.e. not sufficient for charging a phone). A fully powered USB port can quite happily power a monitor; a low-powered USB port will struggle to power anything more than a mouse.

    Each laptop will generally have at most one high-power USB port, and will probably be identified by some sort of orange or blue outline as the “main” USB port. The others will all be low-power USB ports.

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