Micro USB Chargers

[Frank Visconti]

I know this doesn't belong specifically in the LG G3 Forum but if you own an LG G3 you are already smarter than most people ( hehe ). Anyway what makes one MicroUSB charger different than another? I don't understand why some charge better/faster than others when they all look the same. I have about MicroUSB cables from various phones and they all seem to act differently and I can't seem to understand why.

 

[CliveEdinburgh]

For some strange reason, the shorter the cable the better charge I have found this over the years. I remember when I owned(God help me) and iPhone. (yuk spit ) I cast you out ye devil. I had a one metre cable and a genuine 2 metre cable. The one metre cable took say 90 mins to charge, the 2 metre cable 3 hours. Probably wrong but it's a thought. Peace!

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[meyerweb#CB]

It is, unfortunately, a lot more complicated than cable length.

First, the obvious. Different chargers have different output power. The vary from about 500 milliAmps (1/2 amp) to more than 2000 mAmp (2 amps). But that doesn't mean that a 2 amp charger will charge your phone 4 times as fast; the phone circuitry actually controls the maximum charge rate, and any power level above that won't do anything. It's a pretty fair assumption that the output of the charger that comes with your phone is pretty close to the maximum your phone can use. (except see Quick Charge, below). The output power will be printed somewhere on the charger, usually in tiny print, and often in black text against a black background.

Second, there are two approaches to micro-USB chargers, the Apple way and everyone else's way. This gets kinda complicated, so hang on: The USB standard wasn't developed for charging batteries. It was developed to connect low power devices like keyboards and mice to computers. As such, the maximum output of computer USB ports was specified as 500 mA, and connecting a device that tries to draw more current than that can actually damage the computer. So device manufacturers needed to figure out a way to tell if the device is connected to a USB port or a charger. USB ports have 4 connectors, two for power and two for data. Chargers don't use the data connectors. So everyone but Apple agreed that chargers would short the two pins used for data. The phone detects this, and if the data contacts are shorted, allows charging at full power. If the data connectors are not shorted, the device limits charging current to 500 mA.

Apple chose a different method, that doesn't really work any better, but which they could patent, and collect royalties from every company that wants to make an Apple compatible charger. So what happens when you plug an Android phone into an Apple compatible charger? The phone thinks it's connected to a computer, and charges at the 500mA rate. Since Apple is the 500 lb gorilla in this business, an awful lot of chargers are designed to Apple's standard, even if not marked as such. So even if you connect your phone to a 5 amp Apple compatible charger, it's going to act like it's connected to a 1/2 amp one.

But there's a work-around: Search Amazon and ebay, and you'll see "charge-only" cables and "charge+data" cables. Charge-only cables have the data contacts shorted, and will let your phone charge at it's maximum rate on any charger. But note that using a charge-only cable to connect to a computer could damage the PC's USB ports. This is probably only a concern on older computers, but I'd suggest not doing it anyway.

Third, some cheap cables can have much thinner wires, and much higher resistance, than better cables. The more resistance, the more power gets wasted as heat, and the less gets to the battery. But if onc cable really takes a lot longer to charge it's probably defective, or a data cable connected to an Apple compatible charger.

Finally, there's the Qualcomm quick charge standard. A few phones support this, but if you plug a non-compatible phone to it, you won't get any benefit. Why is that? Charging a battery generates heat. The faster you charge it, the hotter it gets. Heat is bad for batteries, and really excessive heat can actually ruin a battery or cause it to burst into flame. That's why phones limit the maximum charging current. Quick charge phones allow very high charge rates when the battery is really low, and then reduce it as the battery gets closer to full charge, when heat becomes a bigger problem. The phone's charging circuitry needs to support this, though.

HTH.