Battery and charging: smartphone terms explained

15 terms. Back to the full glossary.

mAh (battery capacity): Milliampere-hours: how much charge a battery holds. Higher usually means longer battery life, but chip efficiency, screen and software matter too. Typical phone batteries range from about 4000 to 6500mAh, and a few go beyond. Two phones with the same mAh can last differently. Compare real-world battery tests if you can. Related: Rated vs typical capacity, Silicon-carbon battery, Fast charging, Battery health.
Silicon-carbon battery: A lithium-ion battery with silicon added to the anode, allowing more energy to be stored in the same space than standard graphite cells. It lets makers fit larger capacities in a slim phone. Silicon can swell more during use, so makers manage lifespan with design and software. The silicon share varies, and the label does not tell you the ageing behaviour. Related: mAh, Charge cycles, Battery health.
Rated vs typical capacity: Typical capacity is the average a cell is expected to hold. Rated (or minimum) capacity is a slightly lower figure a maker guarantees. Makers differ in which they put on the box, usually separated by a few percent. When comparing mAh across brands, check which figure is quoted. Regulatory listings often show the rated one. Related: mAh, Battery health.
Fast charging (W): Charging power in watts. Higher wattage charges faster, but the full charge time also depends on battery size and how the phone manages heat. The quoted watts are a peak and are not held for the whole charge. Claims such as 0 to 50% in a set time depend on the specific charger, cable and conditions. Very fast charging may need the maker's own charger. Related: USB Power Delivery, PPS, GaN charger, Charger in the box, Charging curve.
USB Power Delivery (PD): A common charging standard over USB-C that lets a charger and device agree on voltage and current, up to 100W and higher in newer revisions. A PD charger can charge many devices, including laptops, but a phone may charge slower on it if it uses a proprietary fast-charge system. Check the phone's supported protocols, not only the charger's watts. Related: PPS, Fast charging, GaN charger, USB-C port.
PPS (programmable power supply): An extension to USB PD where the phone can request fine adjustments in voltage and current, for efficient and cooler fast charging. Many phones need PPS to reach their top charging speed on a third-party charger. If a charger lacks it, the phone may fall back to a slower rate. Related: USB Power Delivery, Fast charging, GaN charger.
GaN charger: A charger that uses gallium nitride components, allowing high power in a smaller, cooler body than older silicon chargers. GaN does not change the charging speed by itself; the wattage and protocols do. It makes high-wattage chargers compact and easier to carry. Related: Fast charging, USB Power Delivery, Charger in the box.
Charger in the box: Whether the phone ships with a charger. Some makers ship only a cable, or a slower charger than the phone supports. Check the box contents on the listing, because the headline charging speed often needs the supplied charger. Buying a separate good charger can add to the cost. Related: Fast charging, GaN charger, USB Power Delivery, Box contents.
Charging curve: How charging power changes over a charge. Phones charge fastest at low battery and slow down as they fill. The last 10 to 20 percent can take as long as the first 50. A phone that quotes a high peak may slow quickly. Time to 50 percent and to 100 percent together give a better picture than a single wattage. Related: Fast charging, Battery health, Bypass charging.
Wireless charging: Charging by placing the phone on a pad, usually using the Qi standard. It is more convenient but typically slower and less efficient than wired and gives off more heat. Wattage claims need the matching pad. Misaligned phones charge slowly. Related: Qi2, Reverse charging, Fast charging.
Qi2 (magnetic wireless charging): A wireless charging standard that uses magnets to align the phone and charger, improving efficiency over earlier Qi. Phones need built-in magnets or a magnetic case to benefit. Speeds depend on the revision of the standard and the charger. Do not assume all magnetic phones are compatible with all accessories. Related: Wireless charging, Reverse charging.
Reverse charging: Using the phone to charge another device, either by cable or wirelessly. It is handy for earbuds or a watch in a pinch, but is slow and drains your own battery. Wired reverse charging is usually faster than wireless. Related: Wireless charging, USB-C port, Qi2.
Bypass charging: A mode where the phone powers itself directly from the charger without charging the battery, reducing heat during gaming. It helps long gaming sessions by avoiding charge heat. Support and naming vary and it is mostly on gaming-focused phones. It does not change battery capacity. Related: Gaming phone, Thermal throttling, Fast charging.
Charge cycles: One cycle is a full 100 percent of use, which may be split over several partial charges. Batteries wear gradually with cycles. Typically phone batteries keep about 80 percent of capacity after several hundred to a thousand cycles, depending on the cell, heat and charging habits. Makers quote different durability claims, so compare carefully. Heat is a bigger enemy than frequent top-ups. Related: Battery health, Silicon-carbon battery, mAh.
Battery health: How much of its original capacity a battery can still hold, usually shown as a percentage. Some phones show it in settings and some do not. Features like charge limits or adaptive overnight charging can slow ageing. For used or refurbished phones, ask for the battery health figure. Related: Charge cycles, Refurbished and renewed phones, mAh.