Quick Answer / Summary: Two charging classes share the connector: 60 W (3 A cords – phones, tablets, small laptops) and 100 W (5 A cords with e-marker chips – full-size laptops, docks). PD negotiates up to 20 V; the cord’s amperage class is the ceiling. Charge-only builds (2 conductors + CC) cost less and charge identically; data builds add sync duty for marginally more. Match the cord’s wattage class to the device’s draw and the charging question closes.
C-to-C charging is the connector’s flagship job – one cord standard from earbuds to laptops – and its entire buying question is one line: how many watts, honestly delivered? The 60/100 W divide, the e-marker that polices it, and the cord builds that carry each class are this guide’s subject.
The Wattage Classes
Power Delivery negotiates voltage (5/9/15/20 V) over CC, and current follows the cord’s class: 3 A builds top at 60 W (20 V x 3 A), 5 A builds carry an e-marker chip in one plug that announces their rating, unlocking 100 W (20 V x 5 A) – and 240 W on EPR-era gear with new markers. The negotiation is safe by construction: a 60 W cord on a 100 W laptop charges at 60 W, slower but compliant; the e-marker prevents devices from overdrawing 5 A builds that lie about their rating. The classes map to device populations cleanly: everything pocket-sized lives at 60 W; everything with a fan lives at 100 W.
The E-Marker, Demystified
The chip is millimetres across, sits in one plug’s shell, and answers one question – ‘am I rated for 5 A?’ – to any device that asks. Cords that need it: anything charging above 60 W. Cords that don’t: the entire pocket-device population. The marker’s cost is a few cents; its absence at 100 W is the difference between full-speed charging and a slow bargain.
Charge-Only vs Data Builds
Charge-only C-to-C cords wire VBUS, GND and CC – two power conductors plus the negotiation line – and skip the data pairs entirely: charging identical to full builds, cost lower, sync zero. Data builds add D+/D- (2.0 tier) and upward, covering the phone-backup-and-transfer case for a marginal premium. The buying logic is the same duty-matching as everywhere in this series: a bedside or car cord is charge-only territory; a desk cord that sometimes moves files is a data build. Neither is better; they are different products for different shelves.
The Desk-Verdict Pattern
Desks that charge and occasionally sync buy one data build per station; the charge-only population lives in cars, bags and bedside drawers. The split usually halves the cord budget without touching a single experience.
Length, Drop and the Honest Wattage
Voltage drop applies at 20 V too: long thin cords sag, and PD’s negotiation reads the sag as a weaker source – a 2 m 28 AWG cord may deliver 85 W where a 1 m 24 AWG delivers the full 100 W. The spec line for charge-duty: gauge stated (24-26 AWG power), length honest, e-marker declared where applicable. The verification: a USB power meter between cord and device reads the actual negotiation – ten dollars of instrument that turns ‘seems slow’ into a number, and the number into a return or a keeper.
The Meter Habit
Fleets that buy cords in volume keep one power meter in the drawer: every incoming lot gets a one-device negotiation read. The habit catches the fake-100 W build at intake, where returns are free, instead of at the exec’s desk, where they are not.
Charging Cord Classes
| Class | Current | Wattage | Devices | E-Marker |
|---|---|---|---|---|
| Standard 3 A | Up to 3 A | 60 W | Phones, tablets, small laptops | Not required |
| High-power 5 A | Up to 5 A | 100 W | Laptops, docks, monitors | Required, in-plug chip |
| EPR class | Up to 5 A @ 48 V | 240 W | Gaming laptops, pro gear | New-generation marker |
| Charge-only build | Per class | Per class | Pure charging shelves | Per class |
Real-World Application Scenarios
An office’s laptop fleet ships with e-marked 100 W cords and the ‘charges slowly’ tickets ended; the 60 W population stays on 3 A cords at half the cost. A rideshare’s console kit runs charge-only 3 A builds – two conductors doing the one job, all day. A home desk’s one cord (5 A e-marked, Gen 1 data) charges the laptop, syncs the phone, and read the SSD once a month – the single-cord life.
Recommended Internal Resources
(1) Product cluster – https://zh-zong.com/productlist/ (anchor: 60 W and 100 W charging cords, charge-only and data builds, e-marked); (2) FAQ – https://zh-zong.com/faq/ (anchor: PD, e-marker and wattage questions); (3) Contact – https://zh-zong.com/contact/ (anchor: request wattage-class cord sets with meter-verified test reports).
- 60 W and 100 W charging cords, charge-only and data builds, e-marked
- PD, e-marker and wattage questions
- request wattage-class cord sets with meter-verified test reports
Related Reading in This Series
- Bulk USB-C Cables: Buying in Quantity Without Buying Landfill
- 6 ft Type-C Cable: The Two-Metre Cord, Its Limits and Its Sweet Spot
- USB 3.0 A to C Cable: The A-to-C Cord, Its 5 Gbps Reality
Frequently Asked Questions (FAQ)
Q: Can I charge my laptop with any C-to-C cable?
A: Only 100 W-class e-marked cords deliver a full-draw laptop’s needs; 60 W cords charge slower or not at all under load. Match the class to the device’s draw.
Q: How do I know if my cable is really 100 W?
A: A USB power meter reads the negotiation: 20 V x 5 A is the real thing. Claims without meters are marketing.
Q: Is a charge-only cable worse?
A: For pure charging, identical and cheaper – it wires exactly the conductors the job needs. The data build earns its premium only where sync happens.