Although the arms race for faster charging seems to have cooled off a little, one company that has consistently being at the forefront is Xiaomi and in this post, we’re going to look at how Xiaomi’s 120W HyperCharge works.
Fast Charging means charging a battery really fast, faster than conventional methods will allow. The standard charging voltage for most chargers (and batteries) is 5W (5V, 1A). This was the case for a long time, so much so that 10W (5V, 2A) was considered to be fast charge. Now Xiaomi have 120W fast charge! Crazy isn’t it?
Xiaomi’s 120W HyperCharge is name given to its crazy fast 120W fast charge technology. The Xiaomi 120W HyperCharge can top up a 4100mAh battery in 15 minutes and a 5,000mAh battery in 17 minutes. Xiaomi for a long time have been at the forefront of faster charging, moving from 10W to 18W, on to 33W, 50W, 67W, 120W, 210W and more recently 300W. The only two companies that come close are are Oppo (with 240W ) and Infinix (260W).
How does Xiaomi’s 120W HyperCharge work?
In order to hit such speeds, the engineers at Xiaomi needed to find a new approach to charging a smartphone battery. The first thing they did was to come up with the dual cell.
A battery unit is also know as a battery cell. What Xiaomi did here was to split the battery into two cells and charge them separately. If you needed to fill up a 50 litre drum with water quickly, would you use 1 tap or would would you use 2 taps? 2 taps would fill up the drum faster than 1.
Dual Charge pumps
Inorder for both cells to charge simultaneously, each cell would have its own separate charge pump. A charge pump is a DC to DC converter that uses capacitors to raise or lower voltage. To speed up the charging, especially during the rapid phase, each charge pump would crank up the voltage so as to speed up charging.
Multiple Tab Winding (MTW)
Multiple Tab Winding (MTW) means opening multiple access points (anodes and cathodes) on the battery. In an earlier post about how smartphone batteries work, I explained the role of anodes and cathodes in smartphone batteries. Think of it like this, if a lot of people needed to get out of a stadium, would one door help them get out faster or would a hundred doors?
Opening multiple access points or multiple tab winding on the battery allows more current to flow from the cathode to the anode which serves to increase the overall charging speed. This also creates a shorter path for current to travel, lowering resistance and increasing charging efficiency.
Mi-FC technology is a proprietary battery technology owned by Xiaomi. It monitors cell current and voltage levels in real time. On most phones, as the battery level nears 100%, the charge speed is quickly dropped to trickle charge levels which slows down charging and increases charge time. On phones supporting Xiaomi 120W HyperCharge, MI-FC pumps in more current which keeps the charge speed fast and reduces trickle charge time.
Xiaomi uses a graphene based Lithium battery which makes the battery more conductive than conventional batteries. It also makes the battery more conducive to higher voltages.
With 120W fast charge comes the real risks of overheating and fire outbreaks. To prevent this, Xiaomi usually installs LiquidCool technology on the phones for quick heat dissipation. In addition, there are 34 charging and safety features from charger to circuit and of course the battery. There are also 9 thermal sensors that monitor temperature in realtime, ensuring that charging is safe.
On the battery there is high and low temperature charge and discharge protection. There is also overcharge protection to protect users from overcharging their batteries.
Inside the charging circuit (IC), there is overheating shutdown protection. This shuts the phone down if high temperatures are reached during charging. There is also protection against under voltage or over current from faulty or malfunctioning USB sources.
On the Xiaomi issued 120W charger, there are protections installed against over voltage, over current supply and high temperatures. There is also cable encryption on the USB cable as well. On every phone purchase, Xiaomi issues a 120W charger in the box for free!
4. Battery capacity
It is a given that fast charge does wear batteries out but Xiaomi claims that their batteries are designed to still hold 80% of their capacity after 800 charge cycles. This is to protect the battery against the adverse effects of fast charging.
These all contribute to ensure that phone charges very quickly and very safely. However, I’m not sure about the veracity of their claims about the protection of the battery’s lifespan.
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