car charger

[mlrz24]

Why is the commando 4g so picky with car chargers? My Verizon charger broke. So I got a couple of non Verizon ones and the phone says the charge is slow use the one that came with the phone. Yet those same chargers work with my friends Droid razor. Just wondering why?

 

[CommandoJ]

There are a few phones (like the iPhone, our Commando's, and a few others) that can actually tell if it is connected to an "official" charger or not. They do this by putting some resistors on the USB data lines of the "official" chargers. If the phone detects the resistors, it "knows" that it's hooked up to an "official" charger and it can suck up as much power as the charger gives it. If it does not detect these resistors, it thinks it's hooked up to a computer that can only provide a smaller amount of power. That's the official line- but it's also because they want you to buy the official chargers.

There are ways around this. You can get adapter cables that have the resistors. Some chargers have this built-in; I have a charger with two ports, one "Apple" and one "Non Apple". The "Apple" port has the resistor. I have this cable, that I can use with ANY USB power source, and the phone thinks it's an "official" charger:

http://www.amazon.com/Mediabridge-C...1412727255&sr=8-3&keywords=USB+charge+adapter

 

[space_cat]

Those resistors and/or voltage control chips control the miliAmps that the charger delivers to the phone. A 'fast' charger like the stock charger are delivering around 2 Amps (1850 miliAmps according to the sticker on the charger). 'Slow' chargers are delivering less than that (around 1 Amp if you look at the sticker on the generic chargers often sold). Iphones and our phones (and others) can gauge the amperage they are receiving and let you know that the low amp charger (slow) is delivering less than the higher amp chargers (fast). If a device not designed for a higher amperage charger is plugged in, it could overheat, so the generic chargers usually are lower amperage so they will work with a wide variety of devices, albeit at slower charge rates.

Page 2 summarizes:

How to recharge the battery of a smartphone or tablet quickly and efficiently

 

[mlrz24]

Thanks for the replies. I learned something about charging cables that I didn't know.

 

[CommandoJ]

Iphones and our phones (and others) can gauge the amperage they are receiving and let you know that the low amp charger (slow) is delivering less than the higher amp chargers (fast). If a device not designed for a higher amperage charger is plugged in, it could overheat, so the generic chargers usually are lower amperage so they will work with a wide variety of devices, albeit at slower charge rates.

Your explanation is a good overview, but there are a few parts that I disagree on.

I've never had any problems with devices overheating due to being plugged in to "fast" chargers with 2 amp ports. Sure, the battery might get a little warmer because it's being charged at a faster rate, but it doesn't cause any issue unless the battery is defective. (Otherwise, how could those 6-socket 10-amp chargers exist without blowing up every device they connect to?)

I don't think the phones measure how much amperage they're receiving. Rather, the resistors in the USB chargers act like a key to a lock. The phone says something like, "Hey, do I see 1000 ohms between pins 2 and 3? Yeah? I must be hooked up to an authorized charger." Then they will adjust themselves to draw more amperage.

I just did an experiment to try and figure this out further. Out of three chargers, I could not get the phone to complain about any one of them. And I had one that could only put out 550 milliamps.

This charger is capable of 2.4 amps. It is the most powerful of the three, you can see the phone is drawing about 790 milliamps and there is no voltage drop.

imgur: the simple image sharer

This charger is the 550 milliamp one. You can see a severe voltage drop and a draw of only 510 milliamps:

imgur: the simple image sharer

This is the charger that came with the phone. Again, 790 mills but there is a pronounced voltage drop of 4.9 volts.

imgur: the simple image sharer

I would have expected the 550 milliamp adapter to cause the phone to throw an error, but it didn't. I'm thinking that the circuitry in the meter fools the phone into thinking it's plugged into an authorized charger.

 

[space wrangler]

I have an Anker Astro 2 portable power bank. It has a 0.6A USB port and a 2.0A USB port. When using the 2.0A port I get the slow charge message. I don't get it using the 0.6A port. I have many aftermarket chargers (car and wall). I don't get this message on any other charger (including my 2.0A Xentris wall chargers).