USB-C charging Test Results

Product Testing

I tested a smattering of USB-C cables and USB PD chargers with a Lenovo Thinkpad E480 which uses USB-C PD charging. I was specifically looking at equipment for off-grid use for solar charging of laptops in a village situation. Is USB-C charging going to be the next big thing? Do different products interoperate well? Is the technology ready for the real world?

“USB PD” is the new optional protocol that allows USB-C devices to negotiate voltages above 5V and current up to 5A for charging. The logo for chargers supporting USB-PD is on the right. I tested 3 different 12V DC “car chargers” which support USB-PD; all of which performed acceptably. I also tested a number of different USB-C cables and the Voltaic V88 Power bank, which is capable of being directly charged by solar panels and outputting USB-C power at 38 Watts. Some of the products I tested have USB-IF certification and others didn’t. I note this in the description. Certification give you assurance the product was properly built to specs and won’t damage anything you plug into it. When charging my Thinkpad E480 all the chargers put out a bit less than their nominal wattage rating, but all performed acceptably. As a reference, with the Lenovo supplied charger I never saw the laptop pull more than 20V @ 2.8A (56W) even though the brick claims it’s capable of 20V 3.25A. Remember that they don’t build custom chargers for each laptop, so the manufacturer supplied charger is usually rated for significantly more than the computer will ever draw.

DC powered chargers

Belkin/Apple USB PD 36W car charger

https://www.apple.com/shop/product/HLRQ2ZM/A/belkin-usb-c-car-charger

USB-IF certified. Actual measured power into the E480 was 32.4W; 11.5V @ 2.82A. This unit worked well but isn’t particularly efficient. I measured over a 5W loss in this very compact device, which causes it to get very warm (135F).

Necteck USB-C PD 45W car charger with 12W USB-A

https://smile.amazon.com/gp/product/B075WQQG7C

USB-IF certified. Actual measured power into the E480 was 39.2W; 20.3V @ 1.93A. Only 2.7w of loss, about half the loss of all the other converters. This unit also has a USB-A port rated 2A for charging your smartphone or tablet. This one is my favorite and we will keep these in stock in our store. Small, efficient, certified, inexpensive. Recommended!

Pwr+ 90W USB-C car charger

https://smile.amazon.com/gp/product/B00G74XXCU

NOT USB-IF certified. Actual measured power into the E480 was 50.7W; 19.8V @ 2.56A. This charger put out considerably more power than the other two car chargers I tested. It should have been able to match the 56W that the Lenovo AC charger put into the E480, though it did not. Theoretically it can do up to 90W if the computer asks for it.

USB-C Power Bank Voltaic V88 Power Bank (45W output)

NOT USB-IF certified. https://smile.amazon.com/gp/product/B07FLK6258/ Actual Measured Power into the E480 was 38.2W; 19.9V @ 1.92A. This PowerBank will charge from a 12V solar panel and provide up to 38W to keep your USB-C computer running while on the road. Didn’t quite reach it’s rating of 45W but at 38W output it will get most laptops fully charged in under 3 hours.

Magnetic Disconnects

A normal USB-C cable connector sticking straight out of the jack makes a big lever arm on the tiny USB-C jack, and USB-C cables tend to be very stiff due to the many wires inside. I highly recommend some sort of a magnetic disconnect on the cord to avoid ruining the jack on your computer, which would render the computer useless with no way to charge it. I tested the “Basevs 4.3A 87W Fast Charge Type C Converter” $14.90 on amazon. https://smile.amazon.com/gp/product/B07G3Z88QM/ It fits on the end of a normal USB-C cable and adds a right angle and will pop apart if the cable is jerked. We will keep these in stock in our store. I also tested their magnetic cable, which is almost identical, except the magnetic connector is permanently attached to one end of a USB-C cable. https://smile.amazon.com/gp/product/B07863DZ4D/ref=ppx_yo_dt_b_asin_title_o04_s00 These devices support power transmission but not data connections. They worked adequately, but I might have wished for slightly stronger magnets. Highly Recommended! There are other similar devices sold which also support data connections, but are larger and cost more. Search for “Magsafe” or “Magnetic USB-C” cables

A Note About Magnetic Dust

We’ve had reports from parts of PNG that the Magnetic Disconnects pick up too much volcanic dust and are unusable, so we also sell short USB-C dongles which are not magnetic. Maybe leave a magnet on your desk for a couple days to see if you collect a lot of magnetic dust before ordering a magnetic USB-C tip.

USB Cables

I tested a variety of USB-C to USB-C cables with various capabilities, since not all USB-C cables are the same. (See my Visual USB Cable Guide for help with understanding the differences.) Since the computer/charger combo I was testing always stayed under 60W, all the cables should have performed the same, and this was the case. I only saw very minor differences in the charging current from one cable to the next. I did not test data transmission speeds, only charging.

Perhaps the most important “feature” of a cable is how well the connector holds up over time. If it gets loose and won’t connect reliably after a couple months, you won’t be happy. Since I didn’t test this, I’m not making any recommendation on these cables, but only stating that they all worked fine in my charging tests when brand new.