# Can electricity from outlets be somehow "stronger" from city to city in the US?

Asked by Mariah (23276) October 1st, 2011

I know voltage is standardized, but is there any other property of electricity that could vary its “strength” from place to place? I’m just noticing that my phone charges much more slowly in this hotel room than it does at home and I’m wondering what could account for that?

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Watts = Volts times Amps
The overall “power” is measured in watts. If the voltage is the same, but there are fewer watts, then there must be fewer amps.

I don’t think that there would be any differences in either volts or amps between cities. It may be possible that the hotel itself has set its electrical outlets to use less power to save money.

Another (probably more likely) possibility is that since electrical lines come with different voltages, from massive transmission cables to small power lines, that the hotel’s power line may have less power than the line to your house.

PhiNotPi (12611)

Could it be that your phone battery discharged to a lower level than usual?

Mine is fully charged at 4 bars, and I usually recharge it when it gets down to 2.

Brian1946 (22260)

Your phone charger operates on FAR less voltage than a standard outlet. Nominally, any city outlet in the US is going to be 120V. Your charger drops that AC input into like 5, 10 or 12V DC. So your charger is just a little transformer. If your phone is charging more slowly, it is not going to be because the input voltage from the wall has dropped to a tiny voltage.

cockswain (15233)

Actually, I need to think about that more. My understanding of electronics is fairly basic, so I’m now wondering if the output of the transformer is always just proportional to the input voltage. So if it’s designed to be an output of, say, 12V when 120V are applied, if the applied voltage was reduced by 10%, would it also reduce the output voltage by the same percent?

I need to read up on it more, but at a glance at the equation on the wiki page it looks like they are proportional. So, if for some reason, some outlet in that room is faulty and only outputs like half the volts, it may take your charger twice as long to charge.

Probably all the outlets in that room are just on a couple circuits. Maybe you could plug the TV into the outlet you’re using and see if it works.

cockswain (15233)

I’d be more inclined to the view that it’s a subjective observation. Unless you’ve actually timed the process at home (and who does things like that?) my hypothesis would be that “you don’t notice the passage of time so much at home”, so what takes the same objective length of time “seems longer” at the hotel, where you are more aware of the passage of time. “Things to do, places to go, people to see” and all that.

An hour at home passes in the blink of an eye. An hour spent “waiting for my phone to charge so I can get out of this room and do something…” is going to be a long hour.

CWOTUS (24386)

@cockswain Transformers come in different “ratios”. A transformer can be set to multiply the voltage by a given number and divide the current by the same number, which maintains the same wattage. The number by which a transformer multiplies volts is hard-wired into the transformer in the form of wire-wraps. If there are less volts to begin with, there are going to less volts coming out of it.

PhiNotPi (12611)

@Brian1946 and @CWOTUS, I don’t think it is perception. At home I can plug my phone in when it’s at 20%, go to the bathroom, come out and it’s at 60%. I did that at the hotel and it was still at 20%. This isn’t the first time I’ve noticed it charging slowly away from home.

I think there is something “special” about our electricity at home. How it’s provided, or something. It’s ridicously cheap compared to other cities, for one thing. I built a theramin a few years back and it was working great at home, then I took it to my boyfriend’s house to show him, plugged it in, and it hardly worked at all. I’m just trying to quantify what that “specialness” is at home. I can’t figure it out.

Mariah (23276)

Perhaps you have larger than standard-gauge wiring at your house, which would allow for greater current flow.

How about a multimeter to quantify your investigation?

I used to occasionally use a Fluke multimeter when I worked for AT&T.
As an aside, we used the ohm meter to verify that distilled water does NOT conduct electricity.

Brian1946 (22260)

Lithium batteries determine the rate at which they get charged, depending on a couple things like their temperature. Is the spot where you charge stuff at your place cooler relative to his place ?

HOLY COW YOU BUILT A THEREMIN ??? Wow, do you still play ?

An AC voltmeter is definitely in order.
If jabbing probes into the wall socket to check the voltage is an issue, I see there is a voltmeter built into “Kill A Watt” power consumption meter that would make it pretty easy.
( Plug KAW into the wall socket, and push the ‘volt’ button.)

I wonder if the low voltage places are victims of neighborhood electric usage expansion, without appropriate expansion of the local power grid capacity. If you can demonstrate that the voltage is below spec they might have to upgrade the neighborhood.

dabbler (15408)

Wait, I’m with @dabbler. You built a theramin? That’s…totally awesomely geekily cool!

Rarebear (23451)

Yes they can actually… *You ask such great questions.

GabrielsLamb (6171)

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