# Would using a 5.7V charger on a phone that officially has a 5V phone cause problems

**URL:** <https://boards.straightdope.com/t/would-using-a-5-7v-charger-on-a-phone-that-officially-has-a-5v-phone-cause-problems/647673>\
**Category:** Factual Questions\
**Created:** [January 19, 2013, 1:11am UTC](https://boards.straightdope.com/t/would-using-a-5-7v-charger-on-a-phone-that-officially-has-a-5v-phone-cause-problems/647673 "2013-01-19T01:11:06Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![Digital\_is\_the\_new\_Analog](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@Digital\_is\_the\_new\_Analog](https://boards.straightdope.com/u/Digital_is_the_new_Analog)\
**Post date:** [February 12, 2013, 2:01am UTC](https://boards.straightdope.com/t/would-using-a-5-7v-charger-on-a-phone-that-officially-has-a-5v-phone-cause-problems/647673/21 "2013-02-12T02:01:36Z")

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> [@AaronX](#):
>
> Don’t new USB (2, not 3) ports provide 1000 mA? I know MacBook Pros can provide up to 1500 mA.

> [@AaronX](#):
>
> Yes, but there are new charging standards for USB. (See the wiki article on USB, power section) Those devices with Y USB cables - especially harddisks, but also optical drives and monitors - if they work with only 1 port plugged in, that port should be supplying more than 500 mA. Also if your iPad charges, as opposed to “not charging”. Lastly, since Europe now uses micro USB to charge all phones, there must be some way of supplying \>500 mA over USB.

You can certainly use more than one port and get more current. You can also use USB 3, which allows for more charge units. But if you are using USB 2 and one port, you are only allowed 500mA by spec.

I have an external DVD drive for my laptop that requires two USB ports to operate. One of used for data and power..the other is only important for power.

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**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\
**Post date:** [February 12, 2013, 5:06am UTC](https://boards.straightdope.com/t/would-using-a-5-7v-charger-on-a-phone-that-officially-has-a-5v-phone-cause-problems/647673/22 "2013-02-12T05:06:17Z")

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And you’ve never gotten it to work with only 1 port? I’ve never needed to use 2 ports on any of those devices.

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**Author:** ![Digital\_is\_the\_new\_Analog](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@Digital\_is\_the\_new\_Analog](https://boards.straightdope.com/u/Digital_is_the_new_Analog)\
**Post date:** [February 13, 2013, 2:03am UTC](https://boards.straightdope.com/t/would-using-a-5-7v-charger-on-a-phone-that-officially-has-a-5v-phone-cause-problems/647673/23 "2013-02-13T02:03:55Z")

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Honestly, I never tried. Next time I have it out, I’ll see if it works. 🙂

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