Lenovo Yoga C640 review: The battery life blows us away

At first glance, it’s easy to dismiss this particular model of Lenovo’s Yoga C640, a Best Buy exclusive with a relatively anemic dual-core i3 Comet Lake CPU, a puny 128GB SSD, and a $600 price tag. That said, this sleek convertible (officially the Yoga C640-13IML) has an ace up its sleeve: a beefy battery that just goes, and goes, and goes.

While this made-for-Best Buy system isn’t a great pick for users looking to process 4K videos or crunch big numbers (there are other Yoga C640 configurations better suited for such CPU-intensive tasks), it could be a great fit for users looking for a versatile 2-in-1 that can go all day long without an AC cord.

Configuration

Lenovo offers three versions of the Yoga C640-13IMLRemove non-product link (we’ll just call it the Yoga C640 from here on out) on its website, including a $850 version (or $770 after discounts) with a 10th-gen Core i5-10210U processor, 8GB of DDR4 RAM, and a 256GB solid state drive, and a $1,000 model ($910 with rebates) with the same RAM and SSD but an upgraded i7-10510U CPU. There’s also a $1,050 configuration that ups the RAM on the Core i7 version to 16GB. All three models come with the same touch-enabled 13.3-inch Full-HD IPS display.

Our review version (81UE000WUS) of the Yoga C640-13IML isn’t listed on Lenovo’s website; instead, it’s a $600 Best Buy exclusive that’s considerably less expensive (and, consequently, less powerful) than the other three models.

Here are the details:

• CPU: Dual-core Intel Core i3-10110U (Comet Lake)
• Memory: 8GB DDR4
• Graphics: Integrated Intel UHD Graphics
• Storage: 128GB SSD
• Display: 13.3-inch 1920x1080 IPS, touch-enabled
• Webcam: 720p, dual-array microphone, physical camera shutter
• Connectivity: One SuperSpeed USB 5Gbps (formerly known as USB 3.2 Gen 1) Type-C port, two SuperSpeed USB 5Gbps (formerly known as USB 3.2 Gen 1) Type-A ports, combo audio jack
• Networking: Wi-Fi 5 (802.11ac)
• Biometrics: Fingerprint reader
• Battery capacity: 60 Watt-hour
• Dimensions: 12 x 8.1 x 0.7 inches
• Weight: 2.88 pounds (3.22 pounds with AC adapter)

Overall, this a typical configuration that we see in budget laptops. The dual-core 10th-gen Comet Lake Core i3 CPU is perfectly capable of everyday computing tasks such as web browsing, Office, and light photo editing, although it’ll start to chug when it comes to demanding multi-core operations like video processing or crunching databases. The 8GB of RAM offers a decent amount of headroom for multitasking or juggling multiple browser tabs.

The 128GB SSD will get cramped awfully fast. Once you take into account Windows 10 and other apps pre-loaded onto the C640, the drive only has about 77GB of free space left. If you store a lot locally, you might want to invest in an external hard drive or cloud storage.

Physically, the 0.7 inch-thick and 2.88-pound C640 is about the same size and weight as other 2-in-1 systems in its class. The fingerprint reader is always a nice bonus. WWhile Wi-Fi 5 networking is standard for laptops in this price range, just remember that you won’t be able to take advantage of the enhanced speed and efficiency features offered by cutting-edge Wi-Fi 6 routers.

We’ve left the best for last, though: namely, the Yoga C640’s 60 Watt-hour battery, which bodes well when it comes to battery life. Later on, we’ll put the battery to the test and see whether it lives up to its promise.

Design

The Lenovo Yoga C640 boasts the same overall design scheme as Lenovo’s other Yoga models, including its angled front edge, flat sides, and the signature Yoga 360-degree hinge. Thanks to the hinge, you can swivel the display all the way around and use the C640 as a tablet, tent it on a desk or tabletop, or sit it keyboard-down with the display angled up for kiosk mode.

Ben Patterson/IDG

The C640’s sandblasted aluminum shell did a nice job of resisting fingerprints, although I could also spot faint greasy hand smudges here and there. While the C640’s flat, nearly featureless lid (save for the Yoga logo) feels smooth to the touch, the bottom half of the chassis has a slight rubberized feel, which helps to keep the laptop from slipping out of your hand.

A couple of other design features worth mentioning include the Yoga C640’s power button, which sits on the right side of the laptop near the hinge, a position that makes it tough to press by accident.

Ben Patterson/IDG

Also worthy of note is the “TrueBlock” privacy shutter for the 720p webcam sitting in the display’s top bezel. The shutter is so subtle that it’s easy to miss, and it doesn’t offer any visual cues whether it’s open or shut. That said, the shutter is easy to slide (I had a much tougher time dealing with the shutter on the Yoga C640’s pricier cousin, the Yoga C740), and given this laptop’s budget price range, it’s a rare treat to get a webcam shutter at all.

Display

Any budget laptop display whose brightness measures north of 250 nits (or candelas) is a plus in our book. All too often, we see bargain laptops with screens that can’t even hit that low-water mark.

Luckily, the Lenovo Yoga C640’s full-HD display, which is surrounded by slim bezels along the top and sides with a chunkier bezel on the bottom, is reasonably bright for a laptop in its price range, measuring 305 nits according to our readings. Granted, we’ve seen plenty of laptops with displays that measure well north of 300 nits (as in 400 or even 500 nits, in some cases), but they’ll generally cost you hundreds more than the Yoga C640 does.

The Yoga C640’s IPS (in-plane switching) display delivers solid viewing angles. The screen dims only slightly when viewed from the sides or the top or bottom, with no signs of inverse colors. The touch-enabled display also did a nice job of responding to my taps and swipes.

Keyboard, touchpad, speakers, and extras

I’ve been impressed by the feel of the keyboards on other Lenovo Yoga models, and the Yoga C640’s keyboard is no exception. They're a pleasure to type on, with a slight concave design, easy discovery, and generous travel (that is, the distance that a key moves when it’s pressed). Each keystroke delivers a crisp, tactile bump, with a refreshingly springy rebound. They keyboard offers two-step backlighting, along with hotkeys for volume, mic mute, airplane mode, Windows lock, and screen brightness. There aren’t any media playback hotkeys, unfortunately.

Ben Patterson/IDG

The Yoga C640’s touchpad sits just below the space bar, putting it slightly left of center. I had little trouble swiping and clicking the touchpad, and I never noticed any jitteriness from false inputs. Even when I intentionally brushed my palms against the bottom corners of the trackpad, the cursor remained rock-steady.

The Yoga C640’s upfiring speakers sounded pretty good for laptop speakers, with a fair amount of detail and even some subtle bass response. Even better is the Yoga C640’s support for Dolby Atmos, an object-based sound format that allows for precise sound placement in a 3D soundstage. Dolby Atmos is generally thought of as an audio format designed for theaters and home audio setups with in-ceiling speakers, but Atmos is finding its way into plenty of devices with only stereo speakers, including phones and laptops. Of course, the Yoga C640’s stereo speakers can’t approach the fidelity of a proper home theater or even external computer speakers, but the laptop’s Atmos-enabled drivers manage to deliver solid audio with an impressively wide and detailed soundstage—well, for laptop speakers, anyway.

Ports

The Lenovo Yoga C640 has a middling selection of ports. On the left side, you get the first of two USB SuperSpeed 5Gbps (formerly USB 3.2 Gen 1) Type-A ports, along with a combo audio jack and a barrel-shaped power port.

Ben Patterson/IDG

On the right side sits the second USB SuperSpeed 5Gbps Type-A port, along with a USB SuperSpeed 5Gbps Type-C port.

Ben Patterson/IDG

While we’re always happy to see a pair of USB Type-A ports (good for connecting, say, a mouse and a printer), along with a USB-C port (handy for newer external hard drives), we’re disappointed by the lack of a memory card reader or an HDMI port. Also missing is a slot for a laptop security cable. You'll likely want to invest in a USB-C hub to extend your connectivity. 

Keep reading for the performance benchmarks and that crazy battery life.

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General performance

With its dual-core Core i3 Comet Lake processor and integrated Intel UHD graphics, the Lenovo Yoga C640 isn’t going to be a screamer in terms of CPU-intensive tasks or graphical performance. As you’ll see, however, the Yoga C640 acquits itself quite nicely when it comes to everyday computing chores (which is what most of us spend 99 percent of our time doing anyway), and as for battery life, well ... you’ll see.

PCMark 8 Work 2.0 Conventional

Our first benchmark simulates such everyday computing tasks as web browsing, spreadsheet tinkering, online shopping, and video chat. A PCMark 8 score of 2,000 or better typically means you’ll see buttery-smooth Office performance from a given laptop. It’s also worth noting that the types of daily PC activities simulated by PCMark 8 are single-core tasks, which means that laptops with quad-core or better CPUs won’t necessarily enjoy an advantage over a dual-core laptop like the Yoga C640.

Ben Patterson/IDG

Looking at our performance chart, the Yoga C640 finishes in second-to-last place, just ahead of another dual-core laptop, the Core-i3-8145U-powered Acer Aspire 5. But check out the Yoga C640’s PCMark 8 score, which is well north of 3,000. In fact, all the laptops in our comparison nabbed a 3,000+ score. Once you hit that mark, you’re not going to notice much difference in terms of performance. In other words, every laptop in our chart should do a great job of handling everyday computing chores, the Yoga C640 included. My real-life testing of the Yoga C640 confirms its impressive PCMark 8 showing.

HandBrake

Our next benchmark measures the performance of a laptop as it encodes a 30GB MKV video file using the free HandBrake utility. This is a lengthy and processor-intensive task that reliably spins up the fans as CPU temperatures begin to soar. Generally speaking, laptops with the most processor cores will rise to the top of the chart.

Ben Patterson/IDG

Unsurprisingly, the Lenovo Yoga C640 sits second-to-last. All the laptops that snagged a better HandBrake score (remember, lower numbers are better in this particular test) have quad-core processors.

Now, we should note that the Yoga C640’s HandBrake showing isn’t bad for a dual-core laptop (we’ve seen scores above 8,000 for other dual-core systems). Keep in mind that when it comes to web browsing, Office work, and most other day-to-day computing tasks, multi-core performance just doesn’t matter that much. That said, if you are planning on encoding videos or crunching large databases on the C640, you’ll have to be patient.

Cinebench

While our HandBrake benchmark generally takes more than an hour to perform, our Cinebench test (which involves rendering a 3D image in real time) is often over in a matter of minutes. That makes Cinebench handy for measuring how a laptop deals with short bursts of intense activity, both in single-core and multi-core scenarios.

Ben Patterson/IDG

Again, the dual-core Lenovo Yoga C640 winds up near the bottom of our chart, slightly ahead of the dual-core Acer Aspire 5. While we’re not surprised by the Yoga C640’s “all-threads” Cinebench score, we are a little concerned with its single-thread result, which is a hair below that of the Acer’s. The single-thread Cinebench mode measures the efficiency of a single CPU core, and it’s odd that the Aspire 5, a laptop with an older Core i3 chip that has a slightly slower boost clock, would beat out (just barely) the Yoga C640’s Comet Lake i3 CPU.

Now, remember that the Yoga C640 passed the PCMark 8 single-core benchmark with flying colors, and I never noticed any hiccups during my day-to-day testing of the system. So while we are surprised by this result, we’ll keep our red flag stowed for now.

3DMark Sky Diver 1.0

With its integrated Intel UHD Graphics core, the Lenovo Yoga C640 won’t cut it as a gaming laptop (although you can game on just about any laptop now, thanks to such streaming gaming services as Nvidia’s GeForce Now and Google Stadia). We still wanted to check its graphics prowess using 3DMark’s Sky Diver 1.0 benchmark.

Ben Patterson/IDG

The results are pretty much what we expected, with the Yoga C640 bunched up with several other laptops with Intel’s standard UHD core. The two laptops at the top of our chart—the HP Spectre x360 and the Acer Swift 3—both benefit from Intel’s newer high-end integrated graphics chips, the G1 and the cutting-edge Iris Plus, the latter of which has been nipping at the heels of discrete graphics cards.

The upshot is that the Yoga C640 will do just fine when it comes to light photo editing and streaming video, as well as Minesweeper-level casual gaming.

Battery life

We test battery life on a laptop by looping a 4K video using the stock Windows Movies & TV app, with screen brightness set to about 250 nits (which meant dialing the C640’s brightness setting down to 94 percent) and adjusting the volume to 50 percent with wired earbuds plugged in.

Ben Patterson/IDG

Thanks to its beefy 60-Watt-hour battery (larger than any of the other laptop batteries in our comparison chart), the Lenovo Yoga C640 shot to the top of our chart, notching an eye-popping 985 minutes (or 16.4 hours) of battery life. That’s a score that eclipsed even the HP Spectre x360, our former battery-life champ when it comes to Intel Core-powered laptops.

Of course, your mileage will vary. If you stream video, crank up the screen brightness, or do anything processor-intensive, the battery will drain more quickly. Still, I tried using the C640 during a few of my usual eight- or nine-hour workdays (during which I’m generally writing stories and doing a lot of web browsing), and the battery almost always made it to the end, no AC cord needed. That’s a pretty neat trick.

Should you buy the Lenovo Yoga C640?

This Best Buy-exclusive version of the Lenovo Yoga C640-13IML may be saddled with a dual-core i3 processor and cramped storage, but it’s blessed with stellar battery life. While it may drag its heels when it comes to multi-core tasks, it cruises right along during everyday computing activities. We’re also happy with its reasonably bright screen and Atmos-enabled speakers. We'd say this is a good choice for budget users who stick to basic productivity tasks. The long battery life makes it a particularly good choice for students spending the day on campus, or a gig worker hopping from a cafe to a lobby sofa to a commuter train (pandemic permitting).