Lenovo Yoga C640 review: The battery life blows us away

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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.

lenovo yoga c640 13iml pcmark 8 Ben Patterson/IDG

The Lenovo Yoga C640's PCMark 8 score may not be a chart-topper, but it still bodes well for smooth Office performance.

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.

lenovo yoga c640 13iml handbrake Ben Patterson/IDG

Laptops with dual-core CPUs generall get lower scores during our HandBrake benchmark, and the Yoga C640 is no exception.

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.

lenovo yoga c640 13iml cinebench Ben Patterson/IDG

As with HandBrake, our CineBench test reveals the limitations of dual-core laptops like the C640 when it comes to multi-threaded performance.

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.

lenovo yoga c640 13iml 3dmark Ben Patterson/IDG

With its integraed graphics core, the Lenovo Yoga C640 can handle light photo editing apps, video streaming, and casual games such as Minesweeper.

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.

lenovo yoga c640 13iml battery drain Ben Patterson/IDG

The Lenovo Yoga C640's battery life score speaks for itself.

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 Yoga 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).

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At a Glance
  • 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.

    Pros

    • Superb battery life
    • Solid everyday computing performance
    • Physical camera shutter
    • Dolby Atmos-enabled sound

    Cons

    • Dual-core processor struggles with CPU-intensive tasks
    • No memory card slot
    • Cramped solid-state storage drive
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