We have a plethora of plug-in USB wall chargers (the kind with that plug into an electrical outlet and have a Type A socket that you use to connect to a device). I’d like to sort through them to find out which are good for our phones, which are good for tablets, etc.
I find a host of USB meters on Amazon, but am not sure what to look for in them—or how to use them once one arrives.
I’ve also been led to believe that charging ability is determined by both the wall plug and the cable itself. Is that true?
I’ve never known there was a difference. I use whatever I can find. I’d be interested in hearing if I’m wrong and what “good for our phones” means compared to “not good for our phones.”
Yeah, the main difference is how much power they can put out, which can affect how fast your devices charge. This should be indicated (in tiny print) on the charger itself.
It is my understanding that a European USB charger, plugged into 220/240, is safe to use in a device with American 110 specs, without any kind of converter, but I’ve never tried it. Anybody know for sure?
The main difference we’ve seen is that some put out enough to charge a phone but won’t charge a tablet (or will barely keep it alive while plugged in and in use). I think this relates to the speed of charge as well.
Most have some fine print, but the difference between them is still elusive.
The USB spec says what types of connectors can be used, what voltages should be present, and how much current a USB port should be expected to be able to source (along with a bunch of communication protocol stuff which doesn’t apply to a charger).
There are two types of USB chargers, those that conform to the spec and those that don’t.
Anything that conforms to the spec is pretty much universal. You can plug any charger into any USB type device (phone, tablet, robotic dog, whatever) without any problem.
The ones that don’t conform to the spec are usually quick chargers. There’s no universal spec for quick chargers (well, technically there are specs for quick chargers but they are new and a lot of chargers don’t follow them). A high-horsepower smart phone often has a relatively large battery for its size so that it doesn’t go dead too quickly, and that battery takes a long time to charge using a standard USB charger. You can use a standard USB charger, though. It will just take longer to charge. When the the phone is plugged into a charger that is designed to quick charge it, that quick charger will supply either a higher voltage or a higher current (or both) so that the phone charges a lot faster.
There are basically two types of quick chargers, those that conform to the USB spec by default, and those that don’t.
Those that conform to the USB spec by default can safely be used to charge any USB device. They only go into quick charge mode when they detect that the device they are designed to quick charge is attached. Exactly how they detect this device isn’t standard, and techniques vary, so a quick charger that works with one phone may not quick charge a different type of phone.
The ones that are a bit dangerous are the chargers that have a USB connector on them but put out a higher voltage and current than that specified by the USB spec. These can damage a standard USB device and should only be used with the device they came with. Fortunately, these are fairly uncommon.
It’s mostly smart phones that have quick chargers.
Most European USB chargers will work fine with anywhere from about 100 volts up to about 250 volts AC, and with anything close to 50 or 60 Hz in frequency. You will probably need a cheapie plug adapter so that you can physically plug it in, but this is just an adapter, not a transformer, so they usually only cost a few bucks (with the usual “squeal like a piggy” multiplier on the cost if you buy it at the airport).
But note that I said “most” and not “all”. You might find one that won’t work with the lower voltages found in the U.S., Japan, and elsewhere.
The charger should be marked with its current output (0.5 amps for basic-level ones, 1.0A or 2.1A for more powerful ones – some will have a mix of 1.0A and 2.1A ports, with the former recommended for phones and the latter recommended for tablets). It should also have an indication of what voltage it will take (110V for US outlets, 220/240V for many foreign ones) – most of the ones made these days will be compatible with both (though most will need an adapter to actually be plugged in to the “wrong” socket type).
Phones want more than the original USB spec provides for, and tablets really need more. So nearly all chargers will provide more, and newer specifications allow for this. The amount of power delivered is limited by the maximum the device will take and the maximum the charger provides, so it’s not a problem to charge a phone that wants 1000 mA with a 2100 mA charger.
So start by looking for what it says on the chargers.
If you then want to be sure, charge your most power-hungry device with the chargers under consideration, and observe how many percent the charge increases in (say) 15 minutes. You need to be between 20 and 80 percent for this, below and above that the rate is different. Leave the tablet alone while you do this, or it will use power for the screen etc and not charge at the maximum rate. If you do this for different chargers you know which ones are the more powerful ones, so you keep those and get rid of the rest.
Of course a small one may be a good choice to carry around in a corder of a bag in case your phone dies. And all else being relatively similar, keep the 100 - 250 V ones in case you ever visit a part of the world with a different voltage. But that’s probably all of them anyway.
There’s another type of charger that doesn’t conform to the USB spec: The cheap piece of trash. If you buy something that looks just like an Apple charger plug, but not made by Apple, you might as well just throw it out: It won’t work well, and it might damage your device.
No, its determined by the lesser of wall plug ability and DEVICE demand…
The device can’t demand more than what the plug end will supply.
How ? they both use switch mode power management…
Anyway, the meters are telling you how many amps the wall plug is supplying to the device currently plugged in. The bigger the better, and its annoying for it to be too small… Too small and the tablet may flatten the battery if in use, and you have to turn it off to get the battery charged.
So you’d test the wall plug on the tablet, and if it can supply 2 or 3 amps, the tablet or GSP may well take that much, and you know its the right one for it. You can then test same plug with phone, and determine the maximum the phone will take… you then find the wall plug that supplies that much for IT … .probably one amp.
All of this should in theory get simpler with the USB-C connector which supports much wider ranges of voltage and amperage and should smart negotiate the correct amount to supply.
I purchased a new adapter for my iPad, since the first cable broke (nice design, Apple). What I thought I bought was an Apple product, just at a much cheaper cost from an on-line source. But I not only got an error message telling me the cable wasn’t an Apple product, but the charge rate was a trickle.
I don’t know if I did any permanent damage to the battery (don’t think so, but bought an Apple power cord to minimize any damage).
I noticed that the new power cords offered by this vendor say that they no longer give the user a warning. That is nice, but I have no idea if Apple has rigged their products to fail when someone is using a non-Apple power supply. As much as I hate Apple for being so damn greedy, I can’t risk killing my devices.
So, if you go with an off-brand, be aware of potential problems.
The Apple Lightning connector (as opposed to the old 30 pin connector) has a chip in it that identifies certified cables (i.e., from a vendor who pays Apple for the right to make a Lightning cable). I balk at Apple’s ridiculous prices for cables, so I bought a number of Amazon Basics cables. These claim to be Apple certified, and all of them have worked perfectly well with my iPhone 6.
I don’t think using a non-certified cable would hurt your device (that would be irresponsibly customer-vicious product design, even by Apple’s standards). The cable just won’t work.
I believe apples security on this has been broken. In Asia you can buy dirt cheap lightning cables that work just fine with an iphone 6 and I doubt very much they are licensed by Apple.