On chargers and phones
Why this post?
The number of "Will this charger work with my phone?" or "Will I damage my battery using this charger?" posts that you see in public fora such as Reddit is quite disturbing. It shows a global lack of understanding of the basic fundamentals that everyone should know to prolong the life of their devices and of themselves in some cases.
I'm hoping to address some of the misconceptions out there in the wild.
Charging Protocols
Brief history
Back in the "old" days there were no charging protocols, or at least there was nothing standard. Each manufacturer would do its own thing with different charging connectors and different chargers providing different voltages. Even different products from the same manufacturer would have different charging requirements leading to people having drawers full of different chargers.
Then came USB. The USB 2.0 (introduced in 2000) type A outlet on laptop and desktop computers was a convenient outlet known to provide 5V and up to 500mA, so manufacturers started steering towards that standard and also provided power bricks with a USB type A outlet on them so that the same cable could be used to charge the phone from the brick and from the laptop/computer. However, they often still had a manufacturer-specific if not model-specific connector on the other end of the cable.
MiniUSB and certainly microUSB connectors changed that and had manufacturers rally around those standards. While the hardware was becoming more standard, it took the introduction of USB 3.0 in late 2008 to increase the maximum output power of a type A port to 900mA allowing a device to draw up to 4.5W.
USB type C connectors began to appear on devices as far back as 2015 on Apple's 12" MacBook. Within a couple of years the practicality of the port's reversable design, faster data transfer speeds and its ability to deliver more power (in particular with the Power Delivery standard) led to its wider adoption by device manufacturers.
By around 2020, USB-C had become the de-facto standard, to the point even where the European Union mandated at the end of 2024 that manufacturers of certain categories of rechargeable devices use it. This really only affected Apple, who was still shipping iPhones, keyboards, mice and AirPods cases with Lightning ports when Macs, MacBooks and iPads were already using USB-C connectors.
PD and PPS — Power Delivery and Programmable Power Supply
The history of the two standards is closely intertwined.
Version 1.0 of PD dates back to 2012. It allowed the device being charged to negotiate a fixed voltage other than 5V with the charger. The standard allowed device and charger to agree on up to 100W (20V at 5A) of power.
Fast-forward to early 2017 and the release of PD 3.0, which is when PPS is formally included as an optional function within the specification. There were many charging specifications around at the time that aimed to reduce energy waste in the form of heat.
The wattage, i.e. the amount of power being transferred, is the product of the current and the voltage when dealing with direct current, so to increase the wattage you need to increase either the current or the voltage. The higher the current flowing through a device, the more heat is generated and wasted, so the best way is to increase the voltage. However, it is advantageous to be able to adjust that voltage in small increments instead of jumping straight from, for example, 9V to 20V. That is what PPS brings to PD 3.0.
In PD 3.1 the voltage range is 3.3V to 48V allowing charging at up to 240W.
Samsung SFC 2.0
SFC (Super Fast Charging) 2.0 is a Samsung-specific extension of PD/PPS, generally allowing charging at 45W by providing 5A at 9V. Because SFC 2.0 is an extension of PD 3.0, a Samsung SFC 2.0 charger is perfectly able to charge a phone that doesn't implement SFC 2.0 but does implement PD 3.0 or later. It just won't charge that phone with a voltage/current profile that isn't part of PD 3.0, so it'll more than likely stick at 9V and 3A, so 27W.
Similarly, while it may be able to operate at 9V 5A, i.e. with a profile that's part of SFC 2.0 but not of PD 3.0, there's no guarantee that a non-SFC 2.0 charger will trigger SFC 2.0 on a recent Galaxy phone that implements it.
Proprietary protocols
Some manufacturers, generally Chinese manufacturers, in particular OnePlus and Oppo, ignore the decadent West's PD/PPS and go and do their own thing. SuperVOOC comes straight to mind.
With such a proprietary protocol sharing nothing in common with PD, a phone using SuperVOOC and a PD charger are unable to negotiate a charging profile. When this happens, the charger falls back to good old USB 5V but provides up to 2A or 3A, so up 10W-15W charging speed, no more. The same thing happens if you plug a SuperVOOC charger into a phone that uses PD. They can't talk so everyone falls back on the safety of 5V.
A word on cables
This is another source of confusion.
The following applies to cables from a reputable brand bought from a reputable store. If you want to buy cheap junk off trading platforms based in the Far-East then all bets are off. You're just as likely to get a knock-off cable that meets none of the standards that it is supposed to meet as you are to get a genuine item. Also bear in mind that many western platforms (Amazon comes to mind) are populated with vendors who advertise items at inflated prices and drop-ship them from Far-Eastern trading platforms anyway, so you're getting the same junk as sold there but at Amazon prices.
Pay attention to the seller's name. I mean no disrespect to the People's Republic of China, but empirical evidence indicates that if the seller has a name that looks like a fistful of Scrabble tiles and is based in China, then there's a high likelihood that you're going to get ripped off.
When a charger connects to a cable, it looks for a chip in the cable called an e-marker. This chip reports information on, among other things, how much current the cable can pass, what maximum voltage it can carry and at what speed it can transfer data. If the charger can't find an e-marker, it makes the assumption that the cable can transport 3A max at 20V max (and data at the USB 2.0 speed of 480 megabit/s but that's outside the scope of this post), so 60W max. This is what the PD 2.0 and PD 3.0 standards say.
If you want the ability to charge faster than 20V/3A then you need not only a charger and phone both able to operate at higher ratings but also a cable that can deliver such a high voltage/current. Only a cable with an e-marker informing the charger of its capabilities will allow the charger to ramp up its output to these levels.
This is also why SFC 2.0 doesn't work with the standard cable provided with Samsung phones. It requires a cable with e-marker stating that the cable can deliver 5A of current.
So, can I use this charger on my phone?
Short answer: Yes.
Longer answer: You might get disappointing results but it won't pose any danger.
The overwhelming majority of phones and chargers implement PD of some version. Most 3.0 and some 3.1. If you try and use a non-PD phone with a PD charger or vice-versa then you're going to have to wait a while to juice up your battery because no high-power charging profile can be negotiated when the phone and charger don't "speak" the same protocol. You'll be stuck at 5V, so 15W tops with a USB-C to USB-C cable.
I've checked and both my phone and charger are PD 3.0 and PPS compliant. My phone is rated at 36W but I have a 200W charger. Is that not going to blow the phone up?
Of course not. That's not how PD and electronics in general work. The rating of the charger is the maximum that it can supply if a device asks for it. The charger will not attempt to ram all of that power into the phone come what may. Also, the rating of the phone is the maximum that it will request during the charge cycle. Let me explain.
When the charge cycle starts, the phone and charger agree on a charging profile based on what the charger can provide and what the phone can work with. If they have several profiles in common then they generally agree on the profile that delivers the most power (this, incidentally, is where PD and SuperVOOC differ: PD will generally go for the highest common voltage to achieve high power charging while SuperVOOC tends to push the current instead). If the charger can provide more than the phone can cope with, it doesn't matter in the least because the phone is never going to ask for something that will destroy it and the charger isn't going to force something on the phone that's beyond the phone's ability to process. The phone will draw what it needs and you'll simply be under-utilising the charger.
As for the phone's rating, that is the highest power that the phone will ever request from the charger. Many factors come into play in deciding how much power to request from the charger, including battery temperature, present charge level and battery health. If there's not much charge in the battery to start with and if the battery is sufficiently cool and not worn out, it'll absorb charge quite quickly. If the battery starts heating up then the phone will take advantage of the PPS function baked into PD 3.0 to get the charger to dial down the voltage. If the battery is in poor health then the phone will want to lower the charging rate to prevent turning it into a spicy pillow. The charging rate is also decreased when the battery is approaching fully charged.
OK, what if my phone has a higher rating than the charger. Will it burn the charger out?
Again, no.
The phone "knows" what the charger can supply (they negotiated a charging profile, remember?) so it's not going to try and draw more than the charger can provide. All that's going to happen here is, the phone won't charge as quickly as it can.
Should I always charge as fast as possible?
That's entirely up to you. You just need to be aware of the consequences of your choice.
Fast charging generates more heat and heat kills the lithium-ion batteries currently used in most phones. If you go for this option then your battery will degrade significantly over the 3-4 years that people keep their phones on average. You could end up with the battery only having a fraction of its original capacity or failing altogether. Having said this, some people do seem to have difficulty organising themselves and find themselves only having a few minutes to charge their phones before leaving home, and fast charging does allow them to top up enough for the duration of their absence and consequent inability to charge.
Slow charging generates much less heat and thus prolongs the life of the battery. Using a low wattage charger to charge the phone overnight is ideal given that Android at least now has the option to charge the battery up to 80% and then wait to finish charging so that the battery only reaches full charge when you get up in the morning. The down-side to slow charging is the fact that you need to be better organised. You can't just toss the nearly empty phone on a slow charger and expect it to charge enough while you're getting ready to go out and last until you get back home.
There's a place for both slow and fast charging. The balance is going to depend on your lifestyle but as a rule of thumb, it's better to fast charge only when you really need it.
