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In the UK electric toothbrushes and razors are usually supplied with BS 4573 plugs.

shaver plug uk

What's the easiest way to charge a UK electric toothbrush in the USA? Using a BS 4573 to regular British rectangular 3 pin (BS 1363) and then a further BS 1363 to US adaptor?

Specifically, my toothbrush is the Oral-B Vitality Precision Clean Electric Rechargeable Toothbrush Powered by Braun. Here's a photo of the base of the charger:

base of charger

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    @pnuts My experience with EE is that they're not very happy with such questions from end users. I think there should probably be competent people to answer it here on TSE. – Revetahw says Reinstate Monica Sep 5 '16 at 17:13
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    Can you get us a photo of the nameplate label on the toothbrush? (I suspect it's on the bottom of the charger.) Also, are you in a house, an apartment, a hotel room, a guest room, or...? – UnrecognizedFallingObject Sep 5 '16 at 18:07
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    Can I recommend... a regular toothbrush? – Malvolio Sep 5 '16 at 18:58
  • I use a converter in the UK as I don't have a shaver socket, so I convert it to a 3 pin. When i go abroad i basically plug my brush charger into my 3 pin converter then my 3 pin into a converter to the country I'm going to. I have done this numerous times in the States and Europe. – BritishSam Oct 10 '18 at 9:43
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+100

Leave the charger at home.

Your charger will not work in the USA, even with a plug-adapter that allows you to plug a BS4573 plug into a normal US "NEMA 1-15" outlet.

How to tell

The base of the charger says

220-240 V AC ~  50-60 Hz 0.9W

UK vs USA

You are using this in the UK on a nominally 230 V AC supply at 50 Hz

Normal† outlets in the USA are nominally 120 V AC at 60 Hz

So you are OK on frequency but the US voltage is way outside the range for which this charger was designed. If the charger could be relied on to do anything useful at 120 V AC it would say so on the base. It is unlikely to even charge the toothbrush at a slower rate. Most likely, it will do nothing at all‡.

It is unlikely the charger would be harmed or catch fire. However any charger you buy in the USA is likely to be dangerous to use in the UK unless the markings on the charger explicitly say it is usable with up to at least 240 V AC.

Choices

As others have said, you can do any of the following:

  • Buy, in the UK, a toothbrush with a charger that accepts 100-240 V AC
  • Buy, in the US, a toothbrush with a charger that accepts 120 V AC
  • Take a manual toothbrush (probably a good idea as a backup)

Notes

† US homes also often have a 240 V AC split-phase supply for high-power appliances such as laundry machines. However these use a completely different type of outlet and plug. You will most likely not have access to these outlets and will not be able to buy an adapter that will allow you to connect a BS4573 plug to any of the multitude of different types of 240 V outlets.

‡ The reasons I expect a 240 V charger to do nothing useful on a 120 V outlet are as follows:

The charger and toothbrush-base are two halves of a transformer. The charging relies on inductive coupling between coils in each part. The effect is to reduce the mains voltage by the ratio of the number of turns in the two coils. The toothbrush then probably has a voltage regulator IC (and some passive components) that expect to receive say 7 V AC and turn it into say 5 V DC - or whatever is needed to charge the rechargeable battery in the toothbrush.

A ratio of coils that turn 240 V AC into 7 V AC will turn 120 V AC into 3.5 V AC inside the toothbrush. It is likely that this will be too low for the regulator to produce 5 V DC from. You would need a more expensive boost-regulator for that and manufacturers generally don't waste money that way.

7

Look at the underside of the charger to see if the voltage range includes 110 Volts. If it is 220-240V only it is very unlikely to work in the USA with just plug adapters. Unfortunately, Oral-B chargers only come with limited voltage ranges, see pictures below.

You could buy a 110->230V voltage converter, but it might be cheaper and/or easier to go to a US drugstore, buy the cheapest Oral-B toothbrush having a charger that looks like yours and use that charger in the USA. I did this for travel with an older Philips toothbrush (the newer models have a wide-voltage travel charger).

As promised, here's the 3757 charger from Mexico (North America) and Germany (Europe) -- especially take note how both are Type: 3757 and yet have different power needs.

US Oral B

EU Oral B

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    An even cheaper solution is to go to a U.S. drug store (or department store) and just by a normal toothbrush. :) Or use the one from the airline amenity kit or hotel, if provided. If you use a charger from a different toothbrush (even from the same manufacturer,) make sure to check the output voltage and amperage ratings to make sure they match the output of your British model. It's ok if the amperage rating is higher on the new charger, but the output voltage needs to be at least pretty close to the same. – reirab Sep 5 '16 at 19:47
  • @reirab, They are wireless RF chargers which have no output ratings. With Philips the handles were the same everywhere, only the input to the chargers was different. I'm assuming Braun is no less sensible. – Dennis Sep 5 '16 at 19:52
  • It makes sense, alas: it works by using a coil and those are voltage sensitive unlike most vaguely IC based designs. I also burnt out a travel kettle previously by forgetting to slide its switch. Moral of the story: think before plug. If it's a coil, beware. – chx Sep 5 '16 at 20:53
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    I actually noticed a third version of the charger on Ebay that is likely for Japan. – Dennis Sep 5 '16 at 22:18
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Yes, your European charger is likely to work with a simple plug adapter.

Experimentation beats calculation:

Right now I am in Japan, with 100 V and 60 Hz, so even lower voltage than the 120 V in the US. I have the same charger, marked type 3757, 220-240 V, and it seems to work perfectly. The toothbrush charged from one to two lights overnight, which is about the same (slow) speed as back home in Sweden (230 V, 50 Hz), and the house didn't burn down. The charger is not warm, and I am fairly confident the house will keep not burning down.

(Trust me. I am an engineer, with lots of vague memories from courses about electricity thirty years ago.)

4

@RedGrittyBrick's insightful answer has made it clear that even with a plug-converter, your toothbrush won't charge. Therefore:

You can buy this voltage converter from Amazon. It will convert the 110V to 220V. I found it on US Amazon, so you can order it there and have it shipped to whatever adress you'll be staying at in the US, so that it arrives roughly at the same time as you.

It costs 9 USD, but that's cheaper than a new toothbrush or charger. And you can use it for other devices as well.

You may have to use it in conjunction with a plug-converter.

enter image description here

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The easiest solution, by far, is to forget the charging sockets and the power socket converters, and just take a normal toothbrush. You can pick one up at your local supermarket for less than £1, and it will take up substantially less room in your luggage to boot.

If you can't find a regular toothbrush with the same level of special magic contours that you're used to (though you should be able to; they're commonplace) then remember, you're not going away forever!

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    @pnuts: It is a valid and valuable solution to the problem "I do not know how to brush my teeth in the USA because I cannot charge my UK electric toothbrush there". Not everything need be taken so literally. :) – Lightness Races with Monica Sep 5 '16 at 20:53
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    @pnuts: Good for him. In my opinion, that was the seed for a good, useful answer. You are free to disagree of course. – Lightness Races with Monica Sep 5 '16 at 21:03
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    @pnuts So? Answers should be posted as answers, not comments. – David Richerby Sep 5 '16 at 21:03
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    @pnuts Sure. You should always downvote answers that you think are bad. And note that you can't downvote comments that you disagree with. – David Richerby Sep 5 '16 at 21:08
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    @pnuts Yet 5 people have upvoted it. – EKons Sep 11 '16 at 11:03
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An electric toothbrush needs to be replaced quite often as the battery wears down. Most have a lifetime of about 1.5 years before they need to be replaced (after that they operate as well as a dull razor).

Get a new one of the same brand in the US and use the supplied charger. Use the new toothbrush with your old charger when you get home.

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    I'm 3 years in on my Braun, and the battery still lasts over a week between charges. I'd be awfully disappointed if my $80 tooth brush needed replaced every 1.5 years. – Johnny Sep 5 '16 at 22:03
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    My wife's is about 3 months old. Aside from the fact that hers goes 2 weeks between charges while mine goes a week, I don't see a difference. – Johnny Sep 5 '16 at 22:16
  • @Johnny I noticed a big difference. I'm not going to argue with your personal experience. This was my experience. I found my answer to be a good solution to an inconvenient problem. The prices and availability in the USA; -Wahlgreens, CVS and what have you makes this solution even more attractive. – Captain Giraffe Sep 5 '16 at 22:20
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Take it, it will still work. I am in the USA now with my AUS 240VAC charger plugged into USA 110VAC outlet and it is charging my toothbrush fine. The little trick I use is, place the toothbrush on the charging dock and then turn on the toothbrush. It will start, then stop and start charging :)

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In any large airport, and many large stores in a city that tourists visit, one can find adapters for the local outlets from/to anywhere else in the world. There are also "universal" adapters that have a female end for every country and male ends that slide in and out with small levers. I think I paid forty pounds for mine, which also had two USB charging ports.

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