# Evaluate this electrical plan. **URL:** \ **Category:** Factual Questions\ **Created:** [August 31, 2012, 1:29pm UTC](https://boards.straightdope.com/t/evaluate-this-electrical-plan/633255 "2012-08-31T13:29:34Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [August 31, 2012, 1:29pm UTC](https://boards.straightdope.com/t/evaluate-this-electrical-plan/633255/1 "2012-08-31T13:29:34Z")
I have a charger for my phone which consists of two parts: A wall-wart style object which plugs into an outlet, and on the other side has a standard A-type USB port, and a seemingly standard USB A to mini-B connector that connects the wall-wart to the phone. I also have a nice GPS watch, that charges with (and syncs my workouts to) a computer using a USB port. It does not come with a wall charger, but does come with an A to A USB “extension cord”. If I wanted to charge my GPS watch directly from the wall, could I use the wall-wart from the phone and the extension cord form the watch to construct a wall charger for my watch, or would that be a Very Bad Idea? As I understand it the voltage on a USB port is always always always going to be 5 volts, although the current a device can draw from a wall outlet can be larger, but given the 5 volts that’s determined by the resistance of the device, right? So I should be all good? Also, I am going to Europe in a week, and would like to charge things there. The notation on the wall-wart (INPUT: 100-240V ~200mA 50-60Hz ; OUTPUT: 5V 1A) leads me to believe that it will handle European voltages just fine and output the standard USB 5V. If I have a mechanical adapter for European outlets, can I use the three components to construct a European wall charger for my watch just as easily as I can this side of the pond? ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [August 31, 2012, 1:36pm UTC](https://boards.straightdope.com/t/evaluate-this-electrical-plan/633255/2 "2012-08-31T13:36:00Z")
I think you’re good to go on all fronts. But if the watch blows up don’t blame me. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [August 31, 2012, 5:06pm UTC](https://boards.straightdope.com/t/evaluate-this-electrical-plan/633255/3 "2012-08-31T17:06:47Z")
Everything sounds good to me. ---
**Author:** ![jonesj2205](https://avatars.discourse-cdn.com/v4/letter/j/ecc23a/32.png) [@jonesj2205](https://boards.straightdope.com/u/jonesj2205)\ **Post date:** [August 31, 2012, 5:17pm UTC](https://boards.straightdope.com/t/evaluate-this-electrical-plan/633255/4 "2012-08-31T17:17:39Z")
Haven’t tried it in Europe, but I have done the wall to charger thing for my Garmin GPS watch without any problem in the US. ---
**Author:** ![pcout64](https://avatars.discourse-cdn.com/v4/letter/p/4af34b/32.png) [@pcout64](https://boards.straightdope.com/u/pcout64)\ **Post date:** [August 31, 2012, 5:20pm UTC](https://boards.straightdope.com/t/evaluate-this-electrical-plan/633255/5 "2012-08-31T17:20:55Z")
For just charging purposes, you should be fine. ---
**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:** [August 31, 2012, 11:35pm UTC](https://boards.straightdope.com/t/evaluate-this-electrical-plan/633255/6 "2012-08-31T23:35:44Z")
Off the record, and absolutely not as someone who deals with, among other things, charging issues on portable consumer devices for a living, I don’t think you’ll have any problems. (wow…that’s a crappy sentence!) -D/a