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I have a Moto G 3rd Gen, and my phone charger broke. I have both the raspberry pi official 10W power supply and the raspberry pi official 13W power supply. Can I use either or both of them to charge my moto g 3rd gen?

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USB standards specify 5V plus / minus 0.25 V which is supplied by pi 10W supply whereas 13 W supply is 5.1 V which is not recommended

So you can use the 10W power supply

Thanks to Ghanima in comments , who pointed out something I overlooked

The 13W supply is listed as 5.1 V with a 2% line regulation (that would be 5.1 V plus/minus 0.1 V) which puts it well within the USB spec

So you can use both chargers safely, as pointed out in other answer giving additional reasons. Sorry for missing this detail

beeshyams
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  • Then WHY does Samsung ship 5.3V chargers? – iBug Jun 04 '17 at 10:38
  • Samsung's "labelledly" 5.3V chargers can even raise output voltage to 5.60V, which is far too higher than 5+0.25V. Well, why? – iBug Jun 04 '17 at 10:48
  • @iBug: good point. OPs device does not support fast charging and for standard chargers reply above is correct. For various fast or quick charging especially from Qualcomm quick charge 3.0 onwards, it is the power that matters and increasing the voltage level (while maintaing a lower current) delivers the required power. This 5.3 V does appear to be a violation of standards but I haven't seen any conclusive result except heated discussion. Do let me know if you are aware. Thanks – beeshyams Jun 04 '17 at 10:55
  • There are (majorly) two kinds of Fast Charging. One is low-voltage, high-current, like the DASH in OnePlus 3/3T. Another is high-voltage, high-currect, the most prevalent solution used by Qualcomm QC series (from 9V to 20V). As is clear, 5V and 5.3V don't make a gap between so it's safe to mix them up. – iBug Jun 04 '17 at 11:16
  • @iBug: I was aware of the first portion but for non fast charging it is better to be on the safer side. As pointed to Izzy in the comments below your answer, resistance drop is long known, so why not 5.3 earlier ( before fast charging came on scene ) remains unexplained- it appears to be linked with requirements of higher power to charge while maintaing safety with a wider range of voltage ( and lesser current) as required in diffrent stages of battery charging – beeshyams Jun 04 '17 at 11:23
  • If you're interested in this, you can buy a USB meter. – iBug Jun 04 '17 at 12:21
  • I am interested but you require more investment than a meter - devices too not to mention that the cost of USB Meters is too high for my liking – beeshyams Jun 04 '17 at 12:25
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    The 13W supply is listed as 5.1 V with a 2% line regulation (that would be 5.1 V plus/minus 0.1 V) which puts it well within the USB spec (though load regulation is unfortunately not listed). So I would think your answer is quite misleading. – Ghanima Jun 04 '17 at 17:32
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    @Ghanima: How did I miss that ? Stupid of me. Will amend answer. Thanks a ton for pointing it out :) – beeshyams Jun 04 '17 at 17:38
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As @beeshyams answered, the USB Standards specify that charging voltage should be 5.00V ± 0.25V, i.e. 4.75V~5.25V.

Most cables have resistance, which lowers the actual voltage that your phone receives. A typical 1-meter long 24AWG cable eats approximately 0.5V. So some good chargers have a feature called loss compensation. These chargers raise their output voltage when a load is detected. In my case a Samsung charger (shipped with S5/Note 4) can raise output V to 5.6V at a load of 2 Amperes. It's completely safe to use the 13W charger if it doesn't exceed 5.5V. It will be faster than the regular 10W one. But if it only output power at 5.1V, the speed boost isn't quite noticeable.

iBug
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  • This may be a reason but then don't you think the standards or earlier OEM devices wouldn't have taken care of it and all along had higher rated chargers ? I am not totally convinced. +1 for bringing this possibility – beeshyams Jun 04 '17 at 11:02
  • @beeshyams As so often, they might have saved a cent or two on that one resistor to boost their marge (instgead of your charging speed). Wouldn't be the first time. – Izzy Jun 04 '17 at 11:04
  • @izzy: possible but I only see 5.3V chargers after quick charging came in so I think this is related to that. See my comment below my answer – beeshyams Jun 04 '17 at 11:07
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    @beeshyams Yeah. I was just throwing in another possibility. Have no special knowledge here, so I cannot tell (but only speculate, which is OT here). Hence I better not "discuss" it :) – Izzy Jun 04 '17 at 11:08
  • @beeshyams More examples: earlier iPad's original charger is [email protected]. Some ZTE phones' original is [email protected] – iBug Jun 04 '17 at 11:18
  • Let's leave Apple out- they pretty much make their own standards. Wasn't aware of ZTE though – beeshyams Jun 04 '17 at 11:25
  • Was ZTE normal or fast charging ? – beeshyams Jun 04 '17 at 11:42
  • @beeshyams Definitely regular normal charging. As I've said, since it's neither high-current nor high-voltage, it can't be fast charging. – iBug Jun 04 '17 at 11:44
  • @beeshyams Despite Apple's making a standard of their own in many extents, this time they can't. They can't guarantee iPhone users always bring its "particular" charger, so they have to compromise and make their specifications compatible with "general" ones. – iBug Jun 04 '17 at 11:47