Charging with a USB cable? Some helpful facts to get the most charge possible



How you charge and how often you charge your phone can affect the life of your battery

In 2016, it is reported that the number of smartphone users is forecast to reach 2.08 billion. That’s roughly 28% of the world’s population and it is estimated that by 2017, over a third of people on the planet will own a smartphone.  Considering that smartphones only really started to take off in 2007 with the introduction of Apple’s iPhone, this is an incredible increase of smartphone users in the past 9 years.
With the strong possibility of 1 in 3-4 people owning a smartphone, the need for powering these devices quickly and efficiently is now in more demand than ever. With the latest chargers offering a “fast charge”, it seems that all our dreams about a longer lasting battery have come true, right? Well, it’s not as simple as that. There are a few factors that can affect how long a battery will last and how quickly you can charge it. 

–    The type and age of both the phone and battery
–    How often you charge your phone
–    When you charge your phone
–    The connector lead you are using (with a USB connector)
–    The quality of the lead you are using (yes, I’m talking to you cheap cables from online shopping and certain retailers)

So let us delve into the world of fast chargers, USB cables and battery life.

Common questions

Does battery life get worse over time?
Yes, your battery deteriorates over time. Modern lithium-ion batteries are designed to withstand a certain number of “cycles” – a full drain of the battery. A cycle is equivalent to a battery fully draining, but this doesn’t have to be from one charge.
As Apple puts it: “You might use 75 per cent of your battery’s capacity one day, and then recharge it fully overnight. If you use 25 per cent the next day, you will have discharged a total of 100 per cent, and the two days will add up to one charge cycle”.
The lifetime of batteries measured in cycles differs between different devices, but typically have between 300 and 500 full cycles before they reach 70 per cent of their original capacity. It is equivalent to a couple of years of use, although this graph from Battery University shows that capacity begins to drop fairly quickly:


Should I wait until my phone battery has gone well down before recharging it, or can I charge it often?
No – in fact, you should do the opposite. Modern lithium-ion batteries gain nothing from being powered down, and long charging cycles are actually worse than short ones.

Partial discharges and charges actually tend to prolong battery life – 50 per cent discharges can happen between 1,200 and 1,500 times (so 600-750 full cycles) before capacity drops to 70 per cent of its original span, compared to 300 to 500 for 0-100 per cent charges. This effectively means running your phone down 50 per cent, charging it up again and running it down to 50 per cent again is better than a full discharge.


Can I use any charger to charge my phone?
Yes and no. As long as you’re using the charger that came with your device (or an approved accessory), you don’t have anything to worry about. Once you branch out into the wild world of third-party chargers, that’s where you need to do a little homework. The cheap USB chargers and cheap USB cables have caused injury, even death in some cases.

But they all fit into my phone!! Just because a charger connects into your phone and may very well start charging it, doesn’t mean that it isn’t damaging the battery. The rule of thumb is that you don’t ever want to exceed the ratings (Amperage) of your device. Going below them (at least on amperage) isn’t going to hurt. It’s when you go over that’s cause for concerns.
Voltage, amperage, and resistance are all interconnected. The higher the voltage, the less loss you’ll have (electricity flows more efficiently at higher voltages), but higher voltage can be dangerous, too. Similarly, amps can be dangerous – even more so than volts. Since everything is interconnected, you need an intelligent charge controller to monitor the battery and adjust the incoming voltage and amperage accordingly. This is where you Power Management Chip (PMC) comes into play to protect your battery and stops it overheating and possibly exploding. Remember the story from above?

Will this shorten the expected lifespan of the battery? Probably not, thanks to the extra intelligence in the charging circuit. However, it should be reiterated, even though our devices use similar charging ports, before you use a charger, make sure your device is rated to handle what it’s dishing out. Failure to do so will very likely shorten your battery life.

What about USB cables?
Remember when I said that voltage, amperage and resistance are all interconnected for chargers? The same applies for the cables that run from the charger to your phone. Just because a cable fits in to your phone doesn’t mean that it will work the best or not damage your battery. In other words, the connectors are the same size but the chargers themselves are not the same.
Finally we need to look at the output amperage, this indicates the maximum amount of current available from the charger for the phone to pull what it needs. If the phone requires 700mA to charge and you happen to use a charger with a 1A output, the phone will draw only up to the 700mA.

However, where your phone requires 700mA and your charger only supplies 500mA, many issues can occur, ranging from very slow charges to overheating and complete device failure. This is generally the BIGGEST problem people come across when they use cheap USB cables.

Do different cable types affect charging speed?

USB cables aren’t all equal and the differences can result in slower charging. Cheaper USB charging cables have smaller wires inside the plastic covers than the ones that came with your phone or a quality after-market cable. This basically means that less power can get from a USB port to your phone.

Think of it this way. The cable that comes with your phone is like a garden hose that has a 10cm diametre. Lots of water can come through and there is not a lot of pressure on the hose. But then you try to use a cheaper hose and this one is only 3cm diametre. You cannot get through the same amount of water in the cheaper hose as the larger hose.

The Main Points

•    The phone will only draw as much power as needed from a charger, regardless of how high the amperage rating is
•    By design, the power management chip in your phone won’t let the battery accept more current than it can handle
•    Some USB ports of a CPU tower will supply 1.5A continuously while maintaining at least 4.3V (the USB minimum) – 4.5V. Some only provide 0.8A
•    The iPhone 6 is able to handle 1.5A. The USB port is rated to withstand currents up to 5A –this is to say that an 2.0 port can handle having 5amps flowing through it but the Iphone’s PMC will only allow up to 1.5amps to flow into the phone
•    Data cables that allow the device to sync to the computer and transfer files can also cause slow charging speed. If you get a cable that’s wired just to charge, it will solve this problem.

•    If you need to use a USB cable that is not the original one that came with your phone (such as a friends), make sure that it is of good quality.

Disclaimer: DPG-formfittings takes no responsibility for how this information is used. It is merely an informative booklet about USB and fast chargers. This is our interpretations of the facts supplied.



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