In a Japanese hotel, using the correct plug converter (to unpolarized prongs, if necessary), do I also need a step-down voltage converter for these items?
Samsung Galaxy S20 pnone
Apple iPhone 13 Pro
Perhaps an iPad
Perhaps a Zendure or other power bank
I only find contradictory and vague recommendations online, very few converters that claim they’ll step down to 100V (but appear only to step down to 110V, which these appliances already are), no info that I can find in a couple of hours on the Samsung website and the phone itself that indicate it is okay with 100V input, and opinions with no cites on Reddit.
Does anyone actually know?
My other options are to charge two power banks in the US or on the plane and use the electronics sparingly during the Japan travel days, or try charging one of the power banks in Japan and see what happens.
Line voltage in Japan is 100V/50Hz. Your charger should list what input voltage it can handle, likely in very fine and hard to read print. It has been years since I’ve seen a charger that can’t handle anything between 100V and 240V AC and 50Hz or 60Hz. As long as the charger handles the input voltage, the only thing you need is a plug converter.
ETA: Parts of Japan run on 60Hz, but it shouldn’t make a difference with any sort of modern charger.
You won’t need a converter for any of those items. If you’re ever not sure, just check if what the input is for that device. You want a minimum of 100 for the voltage and both 50 and 60 Hz (60 for the US and 50 for Japan).
For instance, Googling “Zendure voltage input” I found:
Passport III - All-in-One 65W Adapter for Home & Travel
Pretty much every USB charger these days can handle pretty much every combination of voltage/frequency you will encounter around the world. The devices themselves will get 5V at some charger-dependent amperage through the USB port.
You can check on the charger itself. It might be very small but there should be some fine print like on this linked image that tells you the voltage/frequency range it can handle. Most likely it’ll say 100-200V and 50-60Hz, which will cover Japan.
I’d be more concerned that the charger I bring can supply sufficient power (I’d want at least 1A if not more for the larger devices).
You may need a plug converter, but that’s about it.
Just another data point: my mother’s on a Japan tour now. There was no need for adapters, transformers, or power converters for phones, tablets, camera battery chargers, laptops, etc.
Weird, and – apparently – not without its own downside:
Electricity transmission in Japan is unusual because the country is divided for historical reasons into two regions each running at a different mains frequency. Eastern Japan has 50 Hz networks while western Japan has 60 Hz networks. Limitations of conversion capacity causes a bottleneck to transfer electricity and shift imbalances between the networks.
Some old alarm clocks, also things like motors may care about the exact mains frequency and voltage, but that is simply not an issue for chargers. All you have to do is look at the charger and it will have the input power parameters (voltage, current, etc) printed on it.
Shouldn’t be a problem for most chargers and adapters these days.
Back in the 90s, I had a dialup modem with a wall wart that I bought from the States that didn’t like the lower voltage at times but generally there isn’t a problem with electronics nowadays.
Before 1948, there was something funny about the Southland’s electricity. Plug in a clock from New York and it would lose 10 minutes every hour. Spin a record on a turntable from San Francisco and it would sound deep and drowsy. Some gadgets wouldn’t work at all.
The problem? Southern California’s power grid ran on a different frequency. Like the rest of the U.S., the region was wired for 120 volts, but its alternating current pulsed out of power plants and into electrical sockets at a slower rate—50 cycles per second (or 50hz) versus than the national 60hz standard.
Southern Ontario ran on 25Hz until the 1950s from generators at Niagara Falls when the switched to 60Hz. 25Hz continued to be used by a steel mill until 15 years ago when they decommissioned the last generator station.
A substantial amount of New Orleans pumping capacity runs on 25Hz, provided by a combination of dedicated 25Hz generators and 60Hz to 25Hz frequency converters.
