Why Your Laptop Charger Isn't Charging Your Laptop

A USB-C charger that will not charge a laptop is usually under-powered for that laptop, connected through a cable that cannot carry enough current, or plugged into a USB-C port that does not accept power. USB-C chargers negotiate power with the laptop using USB Power Delivery (USB PD), and the slowest link in the charger, cable, dock and port sets the result.

This guide walks through the quick checks, explains the wattage numbers (65 W, 100 W, 140 W and 240 W), and covers chargers, cables and docks from the store, including the Targus 100W GaN Wall Charger, Targus 65W GaN Wall Charger, Lenovo 65W USB-C Wall Adapter, Targus USB4 Dual Video Mobile Dock 140W EPR and HP USB-C 100W G6 Dock.

Quick diagnosis: why is my laptop not charging over USB-C?

What does the "Slow charger" warning in Windows mean?

Microsoft's USB-C troubleshooting page lists the same causes for both the "Slow charger" and "PC isn't charging" notifications: the charger or cable is incompatible or underpowered, it is plugged into a non-charging port, the port is dirty, or it is connected through a hub or dock. Microsoft's fixes are to use the charger and cable that came with the PC, plug into the USB-C charging port, and clean the port with compressed air. Start there before buying anything. If you are not sure which port charges, our explainer Your Laptop Has USB-C. So Why Doesn't Everything Work? shows how to read the spec sheet.

How many watts does my laptop need?

The quickest answer is printed on the adapter that came with the laptop. Match that wattage or exceed it; a larger USB PD charger is safe, because the laptop only draws what it negotiates. A smaller one may still work, but slowly. Lenovo's own listing for its Lenovo 65W USB-C Wall Adapter (S$62.00) puts it well: 65 W suits laptops that ship with a 45 W or 65 W USB-C adapter, while laptops supplied with 100 W or more "may charge more slowly or not under heavy load". That adapter supports USB PD 3.0 at 5 V, 9 V, 15 V and 20 V and has a UK-type plug that fits Singapore sockets.

The USB-IF sets the ceilings. Until USB PD Revision 3.1, USB PD "was limited to 100W using a solution based on 20V using USB Type-C cables rated at 5A". Revision 3.1 added 28 V, 36 V and 48 V fixed voltages for 140 W, 180 W and 240 W, the range product listings call Extended Power Range (EPR), plus an adjustable voltage mode from 15 V upwards. A 140 W laptop needs an EPR charger, an EPR-capable laptop and a cable rated for 240 W.

Why does the cable matter for charging?

Under the USB-IF certification programme, every certified USB-C to USB-C cable must be labelled with a power capability of either 60 W or 240 W. The USB-IF's own example of a 60 W cable "supports 20V at 3A". Since 100 W at 20 V needs a cable rated at 5 A, a 60 W cable caps a 100 W charger at 60 W, which is enough to trigger the slow-charger warning on a larger laptop. The thin cable that came with a phone is often the culprit. Look for a 240 W label on certified cables, or a stated 100 W or higher rating. The StarTech Thunderbolt 3 Cable (TBLT3MM1M) is rated by StarTech for 100 W PD and 20 Gbps, listed at S$45.00 for 1 m. For display cables, see HDMI vs DisplayPort vs USB-C: Which Cable Should You Actually Use?

Why does my laptop charge slowly on a dock?

A dock keeps some power for itself and its ports, so the laptop gets less than the adapter in the box. The HP USB-C 100W G6 Dock (S$216.00) delivers up to 100 W to the laptop from a 120 W adapter, and the Lenovo ThinkPad Thunderbolt 4 Dock (S$360.00) charges at up to 100 W from a 135 W adapter. Intel's Thunderbolt 4 specification likewise provides up to 100 W for laptop charging. Compare the dock's power-to-host figure with your laptop's adapter. Travel docks with pass-through work differently: the Targus USB4 Dual Video Mobile Dock 140W EPR (S$175.27) has no adapter of its own and passes up to 140 W from a USB PD 3.1 EPR charger to an EPR-capable laptop, or up to 100 W on standard PD 3.0 hardware. More dock checks are in Your New Docking Station Doesn't Work? Here's What You Missed., and brand comparisons in which Lenovo docking station is better and our HP USB-C Dock G5 review.

Which spare USB-C charger should I buy?

For ultraportables and mainstream business laptops that ship with 65 W or less, the Targus 65W GaN Wall Charger (S$60.00, available to order) gives up to 65 W from its USB-C port, supports USB PD and PPS, and adds a USB-A port; Targus notes that with both ports in use the USB-C output drops to 45 W. For 100 W laptops, or a laptop and phone together, the Targus 100W GaN Wall Charger (S$95.00, available to order) delivers up to 100 W from a single USB-C port and has two USB-C and two USB-A ports, at reduced wattage per port when several are in use. Remember the multi-port rule: the headline wattage is for one device. Pair either with a cable rated for the full wattage.

Match the wattage on the original adapter, then make sure the cable can carry it.

Is it safe to use any USB-C charger?

Use chargers from recognised brands, rated for your laptop. In Singapore, the Consumer Product Safety Office (CPSO) states that "power adapters are one of the 33 categories of Controlled Goods" and advises checking that adapters carry the SAFETY Mark before purchase. CPSO also advises using an adapter whose output suits your product and keeping adapters away from moisture. Buying from a reseller that issues a GST invoice and honours local warranty helps too. For setting up home and office desks, see our hybrid-work office tips and 10 Office Gadgets That Look Useless Until You Try Them.

Buying laptop chargers, cables and docks in Singapore

SourceIT supplies Targus, Lenovo, HP and StarTech with local warranty; the Targus 65W and 100W GaN listings state 2 years of local warranty, and for other items confirm the term for your SKU when requesting a quote. Prices are as listed on 23 Oct 2026; the two Targus chargers are available to order and the other items were in stock at the time of writing. Browse Targus chargers and power or the HP docking station collection. Tell us the laptop model and its original adapter wattage and we will suggest a match: use Request for Quotation on the product page, call (65) 6978 3502, email Sales@sourceit.com.sg or use our contact page.

Frequently asked questions

Can I use a 65 W USB-C charger on a 100 W laptop? Often it will charge, but slowly, and it may not keep up under heavy load. Windows may show a "Slow charger" notification. Match the original adapter's wattage for normal charging.

Can a higher-wattage USB-C charger damage my laptop? A USB PD charger only supplies the power the laptop negotiates, so a 100 W charger on a 65 W laptop is fine. Use a recognised brand that carries Singapore's SAFETY Mark.

What cable do I need for 100 W charging? A USB-C cable rated for 5 A. The USB-IF says 100 W USB PD uses 20 V with cables rated at 5 A; a 60 W cable is rated for 3 A. Certified cables are labelled 60 W or 240 W.

What is USB PD EPR? Extended Power Range, added in USB PD Revision 3.1. It adds 28 V, 36 V and 48 V for 140 W, 180 W and 240 W. Charger, cable and laptop must all support it.

Why does my laptop charge slower on a docking station? The dock keeps part of its adapter's power. Check the dock's power-to-host figure; for example, the HP USB-C 100W G6 Dock gives up to 100 W to the laptop from a 120 W adapter.

Why does only one USB-C port charge my laptop? Laptop makers decide which ports accept power. Microsoft lists a non-charging port as a cause of the "PC isn't charging" message; use the port the manual names for charging.