# those 5v usb chargers **URL:** \ **Category:** Factual Questions\ **Created:** [March 11, 2014, 1:54pm UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425 "2014-03-11T13:54:51Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [March 11, 2014, 10:40pm UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/21 "2014-03-11T22:40:00Z")
> [@Dr.Strangelove](#): > > As others have said, baseline USB provides 500 mA and is compatible with pretty much everything, and some chargers can provide more than that. In theory, yes, and maybe for most devices. I can tell you for a fact that the old cell phone I still use – a derivative of the Motorola Razr – will not charge with ANY device except a proprietary Motorola wall-plug or 12v charger. It doesn’t matter what the power capacity of the charger is; it only matters that if it doesn’t transmit the Motorola secret code words, the device lights up and works, but displays “not charging”. Like, “hey, I see lots of power, but I don’t see proof that the required extortion has been paid to purchase a proprietary charging device.” I also have a Magellan GPS that will also quite happily accept power from either of the Motorola chargers, but will not actually charge its internal battery with either of them, but only with its own. And vice-versa. “Universality” in USB chargers is undoubtedly getting better, but it sure as hell isn’t always “universal”. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [March 11, 2014, 10:48pm UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/22 "2014-03-11T22:48:00Z")
> [@wolfpup](#): > > “Universality” in USB chargers is undoubtedly getting better, but it sure as hell isn’t always “universal”. Yup. I suppose I should have said “pretty much everything produced today”. Certainly, in the early days there were all kinds of problems like what you mentioned. Also, it should be said that 500 mA just isn’t enough for a lot of devices. I’ve seen several phones that would (by default) leave their screen on while charging, as well as put the CPU in a high-power state. Unfortunately, the total draw was then over 500 mA and so “charging” it actually drained the battery overall. This has gotten a bit better as well, but it’s still not perfect. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [March 12, 2014, 12:33am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/23 "2014-03-12T00:33:30Z")
> [@bardos](#): > > Please, back to my original question: Could I basically use any 5v 1 amp charger for my IPAD and phone? That is, carry only one charger on vacation, for example and use it for both apparatuses? It’s really simple. You CAN, but it will charge slower. Better to buy a 12 watt / 2.1 amp charger and only bring THAT along. Still one charger, but it’ll charge your iPad quicker and your phone the same speed. ---
**Author:** ![jasg](https://avatars.discourse-cdn.com/v4/letter/j/f0a364/32.png) [@jasg](https://boards.straightdope.com/u/jasg)\ **Post date:** [March 12, 2014, 1:05am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/24 "2014-03-12T01:05:48Z")
I carry only my iPad charger on trips - and use it for iPad, iPhone, Android phone, Kindle, FitBit, JamBox, Garmin nav and Jabra. Sadly, way too many USB cables. No issues at all. ---
**Author:** ![urban1a](https://avatars.discourse-cdn.com/v4/letter/u/e47c2d/32.png) [@urban1a](https://boards.straightdope.com/u/urban1a)\ **Post date:** [March 12, 2014, 1:37am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/25 "2014-03-12T01:37:03Z")
I can remember a bit of controversy about this when the iPad was introduced. At the time the only computer USB ports that produced the 2amp voltage recommended were Apple desktops. Bob ---
**Author:** ![Tabby\_Cat](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@Tabby\_Cat](https://boards.straightdope.com/u/Tabby_Cat)\ **Post date:** [March 12, 2014, 1:43am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/26 "2014-03-12T01:43:37Z")
> [@Reply](#): > > It’s really simple. > > You CAN, but it will charge slower. > > Better to buy a 12 watt / 2.1 amp charger and only bring THAT along. Still one charger, but it’ll charge your iPad quicker and your phone the same speed. This. Also, if you can, bring the original iPad charger, rather than a generic. The power coming from generic USB chargers is generally very dirty, whereas the power coming from Apple charges very clean. This does have an effect on the device - one USB charger I had would cause the iPhone screen to register incorrect touches when charging. I definitely stopped using that charger after that. > **[A dozen USB chargers in the lab: Apple is very good, but not quite the best](http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html)** > > When you buy a USB charger, how do you know if you're getting a safe, high-quality charger for your money? You can't tell from the outside... Check out the oscilloscope traces! Some of those chargers are atrocious! ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [March 12, 2014, 1:45am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/27 "2014-03-12T01:45:23Z")
> [@urban1a](#): > > I can remember a bit of controversy about this when the iPad was introduced. At the time the only computer USB ports that produced the 2amp voltage recommended were Apple desktops. > > Bob It’s still generally true that an iDevice will charge faster plugged into a Mac than (most) PCs because of this, but both are way slower than a wall charger now. For modern devices (iPad 3/4/Retina/Air), the draw on the device _when being used_ may be higher than what a lesser charger can provide – I know, for example, that it’s possible to run an iPad Air out of battery while it’s plugged into a 5W charger (although it takes a long time). In a computer USB port (even a Mac one), you’ll often get a message that the devices isn’t charging – it is, but generally very slowly, and at lower than the rate of use if you have it turned on. Every now and then I’ll bump into that while developing (where the device is on and doing work for many hours). ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [March 12, 2014, 2:16am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/28 "2014-03-12T02:16:10Z")
> [@kayaker](#): > > [I recently purchased this car charger with two slots](http://www.amazon.com/dp/B00GX5ORL4/ref=pe_385040_30332190_TE_M3T1_ST1_dp_1), one delivers 5V, 2.4 amps, the other 1 amp. > > Works great. We just got the same one (a single-pack though) and are very happy with it too. > [@jasg](#): > > Sadly, way too many USB cables. There aren’t that many devices that use the mini connector anymore, but we do tote a couple. Carrying two of these cables ([one cord with a mini and micro connector](http://www.newegg.com/Product/Product.aspx?Item=N82E16812200955)) with us cut down the bulk just a bit. There are Y cables out there too, but we liked the small form factor of this one. Credit goes to the Dope, where I first heard of it. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [March 12, 2014, 5:32am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/29 "2014-03-12T05:32:13Z")
> [@Tabby\_Cat](#): > > This. Also, if you can, bring the original iPad charger, rather than a generic. The power coming from generic USB chargers is generally very dirty, whereas the power coming from Apple charges very clean. This does have an effect on the device - one USB charger I had would cause the iPhone screen to register incorrect touches when charging. I definitely stopped using that charger after that. > > [http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html](http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html) > > Check out the oscilloscope traces! Some of those chargers are atrocious! Amazing resource. Thanks for the link! ---
**Author:** ![guizot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guizot/32/3636_2.png) [@guizot](https://boards.straightdope.com/u/guizot)\ **Post date:** [March 12, 2014, 6:52am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/30 "2014-03-12T06:52:15Z")
> [@kayaker](#): > > [I recently purchased this car charger with two slots](http://www.amazon.com/dp/B00GX5ORL4/ref=pe_385040_30332190_TE_M3T1_ST1_dp_1), one delivers 5V, 2.4 amps, the other 1 amp. > > Works great. > > [And check out this detailed review!!](http://www.amazon.com/review/R1BSQFGYMS2DCH/ref=cm_cr_dp_title?ie=UTF8&ASIN=B00GX5ORL4&nodeID=2335752011&store=wireless) Yes, there are various chargers like that on the market, of equal quality and performance. You can get them on Ebay for a better price than that, too. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [March 12, 2014, 8:56am UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/31 "2014-03-12T08:56:42Z")
> [@bardos](#): > > Please, back to my original question: Could I basically use any 5v 1 amp charger for my IPAD and phone? That is, carry only one charger on vacation, for example and use it for both apparatuses? In general: no, but not because of safety/voltage. There are several USB charging specifications. The major ones are: Apple 1A, Apple 2A and DCP (Dedicated Charging Port). There’s a newer one, for USB hubs, called CDP (Charging Downstream Port). In short, if you test it and it works, you can use one charger to charge both in the future. But you can’t pick up any charger and any device and expect them to get along. If you’re curious about which ports are which, you can get a device like the PortPilot [http://boards.straightdope.com/sdmb/showthread.php?p=16482228](http://boards.straightdope.com/sdmb/showthread.php?p=16482228) Since all devices are converging to USB charging now, it’s worth investing in a good, multi-port charger to save time and space, especially while traveling. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [March 12, 2014, 2:11pm UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/32 "2014-03-12T14:11:33Z")
Slightly off topic: There are[USB charging ports for wall receptacles](http://www.homedepot.ca/product/decora-usb-charger-21a-with-tamper-resistant-receptacle-15a-125v-in-white/809958) now. Clients often choose to put them in the kitchen and bedrooms now. Gets rid of a bulky transformer by submerging it inside the electrical box. Pretty easy to install if you are a little bit handy, can be a tight fit though. Many kitchen receptacles are on two separate circuits top and bottom and that may make things a little more complicated and crowded. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [March 12, 2014, 2:58pm UTC](https://boards.straightdope.com/t/those-5v-usb-chargers/683425/33 "2014-03-12T14:58:44Z")
> [@FluffyBob](#): > > Slightly off topic: There are[USB charging ports for wall receptacles](http://www.homedepot.ca/product/decora-usb-charger-21a-with-tamper-resistant-receptacle-15a-125v-in-white/809958) now. Clients often choose to put them in the kitchen and bedrooms now. Gets rid of a bulky transformer by submerging it inside the electrical box. > > Pretty easy to install if you are a little bit handy, can be a tight fit though. Many kitchen receptacles are on two separate circuits top and bottom and that may make things a little more complicated and crowded. I’m in the process of attempting to convince a bar-owner/friend to install these along the length of the bar. [Previous page](https://boards.straightdope.com/t/those-5v-usb-chargers/683425.md?page=1)