Is it safe to charge tablet from phone via OTG cable if tablet's adapter is 5.2V (a bit above)?

  • Your question does not make sense to me. Charging one device from another only works if both devices use USB-C and the power providing device supports USB power delivery. For USB-C there is no such thing as an OTG cable, just us an USB-C to USB-C cable with USB-PD support. And why you mention the tablet (charging) adapter is totally unclear to me as it is not relevant at all.
    – Robert
    Commented Dec 18, 2019 at 18:19
  • "Charging one device from another only works if both devices use USB-C" - thanks, didn't know that. I ordered LG V20 with extended battery and I have Lenovo Tab 10. As musician, I have a lot of screen on time because I use tablet as sheet music. So I want to be able to charge my tablet from LG V20 extended battery.
    – Pranciskus
    Commented Dec 18, 2019 at 18:45
  • 2
    The LGv20 has a 3200 mAh battery and the Tab 10 one with 7000mAh. Charging the large battery using a much smaller one is not very effective. May be you should better look for a power bank.
    – Robert
    Commented Dec 18, 2019 at 18:49
  • I ordered this extended battery and I want to carry less things.
    – Pranciskus
    Commented Dec 18, 2019 at 18:51
  • 1
    The cable you have linked to is just a plain USB-C male to USB-A female cable. OTG is specific to micro USB ports (one special pin is used to identify if a cable is an regular or an OTG cable). For USB-C there are no such thing like an OTG cable. You can just use regular adapter cables and it works as you already have found out.
    – Robert
    Commented Dec 19, 2019 at 8:28

1 Answer 1


Yes, as long as it is supported by the tablet and you have compatible cables available.

USB Standards specify that charging voltage should be 5.00V ± 0.25V, i.e. 4.75V~5.25V.

Upper limit is 5.25V which is higher than tablet adapter voltage ; add to this the resistance offered by the cable and the input voltage will be well within safety limits.

How efficient it would be is upto you to verify as Robert pointed out in comments

  • Thank you for answer! Another thing: if I charge like that, will I lose almost 50% of energy. Because when energy goes from battery to cable it loses ~25% and after that when goes to another battery will I lose another ~25%?
    – Pranciskus
    Commented Dec 19, 2019 at 8:05
  • Cable losses are not so high as you suspect. You can buy a good cable. For help see this answer. How much over all loss you would have needs to be tested by you. That said, power bank is a better option as suggested by Robert
    – beeshyams
    Commented Dec 19, 2019 at 8:46
  • I don't really understand why power bank is better option if I will have 10500mAh battery for my phone. Anyway, is loss by charging using phone will be higher than using powerbank?
    – Pranciskus
    Commented Dec 19, 2019 at 11:00
  • From your answer I understand that cable thickness matters.
    – Pranciskus
    Commented Dec 19, 2019 at 11:14
  • yes............
    – beeshyams
    Commented Dec 19, 2019 at 11:17

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .