Tuesday, December 31, 2013

USB charging adaptors and cables

Have you ever encountered a situation where your phone charges very slowly or even worse, draining battery while plugged into a wall or car charger? Yes, you are not alone. I have encountered it as well and only understood why it happened like that after wasting money on many adaptors and destroying multiple USB cables. Now let me explain why and hope it helps you from going through all the hassle like I did. This has something to do with Apple devices (sorry Apple fanboys) for selfishly not following the USB specs and in the process screwing up the USB aftermarket charger specs.

Firstly, let's explore the USB specs in order to understand how it works. USB cables come in 4 lines. The outer 2 lines are for power supply while the middle 2 (green and white) is for data. When used with a computer, it works as a sync cable enabling data transfer while still able to draw power supply to power or charge the device. In my best knowledge, USB 2.0 ports only supply maximum 500mA while USB 3.0 ports up to 900mA. So in this case, your charging rate is limited by the USB port to either 500mA or 900mA. Modern smartphones drain power at more than 1.0A (1000mA). Therefore it is almost impossible to fully charge a phone while it is powered on and being used. It will only slowly charge to full if you leave the phone in idle state (display off).

Now comes to wall chargers and adaptors. Off the box, normally manufacturer's adaptors charge your phone at an amazing rate. Why? Let's go back to the 4 lines in the USB cable. If the 4 lines in the cable are connected to the 4 pins in the adaptor, your phone will sense that it is in sync mode as if being connected to a USB port. Therefore your phone will command a power draw of maximum 500mA. This has got to do with the USB specs and not to fry the computer USB ports by demanding higher power that it can supply. So does that mean if you connect the USB cable to the wall charger and the other end to your phone, you will only get slow charge rate of 500mA? This is where the manufacturer's adaptor works the magic. Their adaptors have been modified to exclude the 2 data pins so when plugged into your phone, your phone will only sense pure AC charging mode allowing it to draw current up to the maximum limit the adaptor can provide, normally in the range of 1.0A, 1.2A or 2.1A. You are able to charge your phone just fine so why did I mention Apple earlier?

Smartphones are so versatile and mobile now. Your charging woes start once you decide to invest in extra adaptors and car chargers to cater to your mobility needs. It is a hassle to carry only one adaptor so people invest in extra chargers and leave them in convenient places like cars and luggage bags. For years the EU had been pushing for a standardization in USB charging specifications considering the many brands and different types of adaptors available previously. Thanks to them, now we have a standardized mini USB and micro USB charging specs that all manufacturers can adopt. Looking for a charger during emergency is hassle free now since everyone is using the same kind of adaptors. You can easily borrow any USB wall charger from your friends if you need one to charge your phone. Now comes the Apple part. They selfishly ignore the USB standards to come up with their own specs. To charge an Apple device, you need all the 4 pins in the cable and adaptor. They work differently by using the data pins to communicate between the device and the adaptor, then only to decide how much current to draw from the adaptor. By having different standards, Apple is forcing the consumers to buy their overpriced accessories. And they had been using loopholes in order to bypass the EU for having a standardized USB charger.

What has it got to do with non Apple users then? As time passes, the aftermarket accessory manufacturers catch up to come up with their own cables, adaptors and car chargers. Now in order to kill 2 birds with 1 stone, they manufacture adaptors that can work for both Apple and non Apple devices. But by doing this, non Apple users will be short changed. This is because in order to work with Apple devices, the adaptors come in full 4 pins and the 2 data pins are not short-circuited. So when you plug in your phone, it will only sense USB sync mode and draw maximum 500mA even though your adaptor shows higher output. As a consumer, you will be fooled when you buy extra adaptors and car chargers for your needs. Most aftermarket adaptors are labelled to work with both Apple and non Apple devices. But what you don't know is these adaptors are not USB standard which must have the 2 data pins shorted. So thinking you may have bought a slow charger, you move on to buy multiple chargers at higher ratings but only to discover it is still not charging your phone. Your money is wasted and you're fuming, blaming non Apple products are inferior whereas the fault lies with Apple in the first place.

So what can you do? The safest way is to buy the original manufacturer's adaptors. But those come with a slightly higher price tag. And when it comes to car chargers, you won't have many choices unless you buy the aftermarket accessories which most likely are made in China and non-USB compliant with fake compatibility labels. As of this moment, there are only 2 solutions. One is to modify USB cable yourself to short circuit the 2 data lines. The method is available here in this video. The second option is to buy a USB charge only cable. These cables are modified to short out the data lines. But this is a niche market and finding USB charge only cables is hard. Beware of the many made in China cables that label USB charge only but they are not. One way to find out is to plug the cable attached to your phone into the computer. If it detects your phone and allows you to transfer files, then it is not USB charge only cable. I'd recommend you this cable by PortaPow from the UK. By using this cable, you don't have to worry whether the adaptor or car charger is USB standard or not. Just plug this cable in and your phone should charge at the full rated output. There is the 3rd option actually but finding it is like finding a needle in the haystack. You can buy a USB standard car charger but like I said earlier, it may be labelled misleadingly. PortaPow sells car chargers like these that are labelled USB standard but it is up to you to verify with the seller.

Final tips before I end. If you own Samsung phones or as a matter of fact any Android phones, you can easily check whether you are on AC charging or USB (max 500mA) charging when you are connected to the wall or car charger. Simply go to your settings and battery page. It should show you whether it is on AC or USB next to the charging status. If on AC, bravo your phone is charging normally at the maximum output from the adaptor. If USB, it's either your phone is plugged to your computer USB port, or your wall adaptor/car charger is not USB compliant. You've been ripped off, thanks to Apple.

Addendum 1: The downside of using USB charge only cable is you cannot use it for data transfer now. So be sure to label or mark your USB cables correctly to save you the trouble next time from using wrong cables for data transfer between computer and phone.

Addendum 2: Will my device blow if I connect a 2.1A charger (labelled/meant for Ipad) whereas my original manufacturer's adaptor only churns out 1.0A output? The answer is no. Smartphones are smart enough and well protected to accept higher current. In fact the higher amp the better because it will decrease the charging time. If the current exceeds more than the phone can take, it will be smart enough to disconnect while most probably showing a message or icon of incompatible charger.

Addendum 3: Thickness, length and material used in a USB cable also play a role in determining the charge rate. As like any other electricity cables, resistance in the cable decreases current as some escape as heat. Ideally, a 1 meter rounded cable is better than made in China 3 meter noodle thin cable. Less length means less resistance and a thicker cable allows more current to flow through. However there must be a balance between thickness and length. You can forget about those fancy China made colorful noodle thin cables. Not only they are long, the wires inside are just few strands wrung together shoddily. Even if you mod the cable to short out the data lines, a 2.1A input will only output less than 500mA when it reaches your phone.

Addendum 4: Newer phones like the Note 3 shouldn't have any problems charging in any chargers. I presume they have been modded to counter all these thrash aftermarket Iphone only and non USB compliant chargers. But that means they are deviating away from the USB standards. It's a sad day indeed to give in to just one selfish company.

Addendum 5: If you own any portable powerbanks, then you may be in luck finding the cable provided is most likely USB charge only cable. Go ahead and give it a try. Even though short, but hey it's better than nothing. You can use it for your in car charging.