"A good charger would provide you with at least 2.1 Amps (or 2100 mA) per USB port. This is so that you can also charge your Android tablets and iPads at their optimal speed since smartphones usually only require 1.0 Amps (or 1000 mA). So if you’re looking for the highest performing dual USB car charger, you want to look for a 4.8A USB car charger. This means that each USB port provides 2.4 Amps, which is more than sufficient to charge two iPads simultaneously. On the other hand, if the Amp output per USB port is below 2.1 Amps per USB port, the charger would do well charging two smartphones, but not as much with two tablets."


https://www.nonda.co/blogs/news/134768647-3-things-to-look-for-when-buying-a-usb-car-charger

You should find out what the amp rate is for the wall plug-in charger that the phone came with and use the same for the phone with a car charger. Not all phones are made to handle higher charge inputs than the stock charger provides. Doing otherwise could lead to an earlier battery failure or even a fire.

Thank you, that is what I was wondering. I looked at mine...is it the input or output? It says input 100-240V output 9.0=1.8A or 5.0=1.8A

???

A higher amperage charger can't and won't charge your phone or other device "too fast" and start a fire. Your phone and its battery determines what it can take, and a higher amperage charger will simply allow more power to flow IF your phone can accept it. Think of it like this: you can plug a microwave oven (10+ amps) into the same 15 or 20 amp outlet that you can also plug a night light (0.1 amp or less) into. That electrical outlet doesn't push power into the device; the device draws what it draws. In this situation it's an overloaded outlet that could give you problems not an "underloaded" one.

Going back to your charger, the only risk could come from using too high of a charging voltage, which could indeed overheat the battery, but anything USB is going to be rated at the same charging voltage. (Back before virtually everything was USB, phones and other stuff did charge at different voltages, so the wrong charger could have overheated or otherwise damaged the battery.)

So, there's no harm at all in buying the highest amp output USB charger you can find. If anything it's safer because the charger itself will run cooler. I've seen some of the 500 milliamp cheapies get very hot when you charge something like an iPad off them.

I'm not a battery engineer but I think the comments in the preceding post are incorrect. The analogy to an AC electrical draw is irrelevant because the issue is the amperage applied to a battery to charge it, not the draw from the power mains that first goes through a transformer (which is what's plugged in).

Instructions in cell phone packages caution to use only the supplied charger. I think that may be overly cautious but to offer an unsupported suggestion that a quick charge device can be used with any phone is a bit reckless. All batteries have a spec for recommended max amperage for charging. That information may or may not be easily obtainable by the average device owner, but it does exist. In the absence of information, using the supplied charger or a car charger is probably the best course

Here's one random write-up I found from a search, there are many to the same effect. Is this guy authoritative, I don't know, but it's consistent with what I've always heard.

Chargers aren't interchangeable

PS - I think it's far more accurate to say that electricity flows through wires and into things plugged in, not pulled.

Amperage is not "applied" to devices; it is drawn by them. You lack an understanding of electricity. My analogy of the home electrical outlet is absolutely relevant. Did you bother to read the article you linked? While it does include some misleading information of the same ilk you're stating here, it says a higher amperage charger is no problem - it's a lower amperage one that could cause a problem, they correctly say.

Here are some other articles from authoritative sources:

Extreme tech story

Wired magazine charging story

Charging devices FAQ (Wired)

In short, USB was created to provide a charging and mobile power standard. As I explained above, the wrong charging voltage can cause a problem, but that won't happen here because the USB voltage is standardized.

Now, as to why manufacturers recommend their own chargers: These devices do vary widely in quality. "Dollar store" chargers may lack good voltage regulation, and they may not meet their published specs.

Your statement that it's "reckless" for me to say it's okay to use a higher amperage charger is based on ignorance, and has led you to pull in more terms you don't understand. A "quick charge" device would supply higher voltage, as battery charging amperage is determined by the voltage applied, not the charger's maximum amperage. Lenovo's Moto G series phones make use of this in their "turbo charge" phones, but you can use their "turbo charger" with any phone you like (they say so) because charge regulation is in the phone.

Your P.S. comment is simply an attempt to quibble over semantics. Power is said to be "pulled" in colloquial conversation to illustrate that different devices draw different amperage when plugged into exactly the same voltage. Because you do not understand that you're trying to create a distraction.

"USB was created to provide a charging and mobile power standard."

No, I think this is incorrect too. USB was created as a standard (and dare I say, universal) way to connect peripheral devices to PCs. Because many such connected devices need power, the downhill USB connection supplies that. That downhill power can be used for other purposes, like charging various devices that are USB capable.

I don't view my comment as quibbling with semantics at all. You said:

"That electrical outlet doesn't push power into the device; the device draws what it draws."

Yes, common usage is to talk about "draw". But that's not how electricity behaves. That's why with whatever words you want to use, I believe this statement of yours is also incorrect. I'm not a "do a search and pretend to be an expert" type.

Now you're changing the subject. The original question was, in essence, can a higher amperage USB charger be used with a phone that came with a lower amperage one. The answer, as I correctly stated, is yes. The three sources I gave above, as well as the one you supplied but didn't read, all say exactly that, as well.

If you want to talk about power flow through batteries and electrical devices, I'll put it separate so as not to confuse the above.

You're right - draw and pull aren't really the right words to use. They're colloquialisms I've used for years in my job. "This pulls 10 amps," etc. The best analogy, and the one that was often used in my education, is to liken the flow of electricity to that of water in a pipe. A higher amp circuit is a bigger pipe. A higher voltage circuit is like a pipe with higher water pressure. The current-using device is like the faucet you open or close. Higher pressure (voltage) and lower resistance (Ohms) are what will increase the current (amps) through the circuit. Amps do not exist until current begins flowing. Amperage ratings of power delivery equipment refer to the maximum allowable amperage the circuit or device can safely carry. Amperage ratings of power consuming equipment refer to the maximum amperage they'll carry in normal operation.

To relate that to this discussion, it should now be clear why a higher amperage charger is fine: it's merely a bigger pipe that can deliver more current if needed. That doesn't mean the current will flow - the voltage and resistance will determine that - but that it can flow if needed, exactly as I started in my analogy of the night light and the microwave oven.

Charging batteries is an interesting area, because you can observe what happens with a device called a Kill-a-Watt that indicates the wattage used by any device you plug into it. I have a 12-volt car battery that is one of those "booster" batteries you can use to jump-start your car if there's no other car around. You charge this battery with a supplied plug-in charger. If the battery is heavily discharged, the charging wattage will show about 14, but as the battery nears a full charge, the wattage slowly drops to about 2, and at that point you can unplug the charger. This happens because as the charger continues to supply a constant voltage, the charging current drops as the battery's internal voltage nears that of what the charger is delivering. This all occurs not as a function of any type of computerized circuitry in the charger, nor as a result of the charger's maximum amp rating, but simply because of how current flows in the battery charging process. "Smart" chargers can affect the charge rate of a battery by applying different voltages at different phases of the charging process, as batteries of different chemistry do better with faster, slower charges or other specific things, such as high voltage early and low voltage late in the charge, or whatever. Most cell phones today have charge control circuitry to somewhat counter the detrimental effects of constant overcharging, as people frequently do when they charge the phone all night while it's still turned on and they're asleep.

I have a Motorola fast charger .. 2.4 amps - also have inline volt/amp meter I've played with to compare the little android Amp apps which surprisingly are close enough accurate. Anyhow maybe a dozen phones here for various rooms and various purposes. Most phones will only use 1 amp or less from that charger and certainly have lasted a long time. Think three of them actually can use the full 2.4 amp. Voltage goes up and tapers down in steps for the phones capable of accepting a fast charge,, 5/9/12v and of course the current always tapers to near nothingness on all the phones when they reach full charge.

kenjwy mentioned Moto G, have 2 of the Moto G3 here, which are 2 or three models old now.. they are my phones next to my laptop.. those guys are capable of 8 days on wifi for the 2part security sites & give notifications to Cortana too for other things so I don't need run them at start on the laptop, yahoo mail, Hotmail, gmail, etc.

Yes, I have a Moto G4 with the "turbo charger" and as you said it steps up the voltage to effect that fast charge. Qualcomm makes circuitry in that phone that works with that charger. Also as you said you can use that turbo charger with any other phone or tablet you want and there's no problem.