Back in the days when the first rugged laptops appeared, the battery life of laptop computers was in the 1-2 hour range, and even when we launched RuggedPCReview.com back in 2005, we rarely saw more than 3-4 hours. Today's customers generally expect full-shift operation, and manufacturers deliver. How far we've come.

That said, it wasn't easy. While battery technology has come a fairly long way, it has not kept pace with the far more dramatic increases in processing power. And today's customers want their laptops and tablets sleek and light, and that again is a problem because batteries are quite heavy.

So how does all of this affect the DURABOOK S15? Well, over time the company has tried different approaches with the big-screen S15 platform. The original 6.5-pound DURABOOK S15C, launched in 2011, had a small 48 watt-hour that only yielded about 3.5 hours of operation. The DURABOOK S15H we tested in 2014 came with a much beefier 87 watt-hour battery that lasted more like 7.5 hours. That was progress, but the machine still weighed a hefty 6.6 pounds and was an inch and a half thick. The S15AB we analyzed in 2016 came with a 59 watt-hour battery and weighed in at 5.7 pounds. Now, the latest S15's hybrid processors provide higher performance at lower battery power draw.

We tested the power draw of the S15 with our standard BatteryMon benchmark. With the Windows 11 Power setting set to "Best Power Efficiency" and the display backlight set to its lowest setting, we saw a minimum draw of about 4.2 watts. That's theoretically good for 13.3 hours, a bit more than the company's 12 hour estimate.

DURABOOK S15 BatteryMon Power Draws (at idle)
	Backlight level	Darkest	50%	Brightest
	Max Battery	4.2 watts (13.3 hrs.)	5.6 watts (10.0 hrs.)	12.1 watts (4.7 hrs.)
	Max Performance	4.5 watts (12.4 hrs.)	5.9 watts (9.5 hrs.)	12.5 watts (4.5 hrs.)

With the backlight set to roughly 50% for comfortable indoor viewing, we saw a minimum of 5.6 watts, theoretically good for ten hours. And with the backlight set to maximum brightness, power draw went up to 12.1 watts, theoretically good for 4.7 hours. We then switched the Windows 11 Power setting set to "Best performance." That way, with the display backlight set to its lowest setting, we saw only a very slightly higher minimum of about 4.5 watts. With the backlight set to 50% for comfortable indoor viewing, we recorded 5.9 watts, almost the same also. And with the backlight set to maximum brightness, power draw was 12.5 watts, theoretically good for 4.5 hours.

Real-world mileage will depending on many variables. Measuring minimum draw in a test lab is not an accurate predictor of actual battery life. As far as real world battery life goes, PCMark 10's Battery test shows how long a charge lasts with the system never sleeping and constantly being exercised with a variety of typical tasks. In that test, the latest DURABOOK S15 scored a 7:08 hours, not the twelve hours in the specs, but respectable for the system running at uninterrupted load.

Very good display

The DURABOOK S15's large display measures 15.6 inches diagonally and it uses the "full HD" 1920 x 1080 pixel resolution, which translates into a wide-format 16:9 aspect ratio. 1920 x 1080 resolution in this size display makes for 141 pixels per inch. Full HD is still pretty much the norm in semi-rugged and fully-rugged laptops. Given the very high pixel density of today's smartphones and consumer tablets, as well as the 4k resolution of many PC monitors and almost all TVs, we hope to soon see higher resolution on professional laptops as well.

That said, at least 1080p is standard now on the S15. That wasn't always the case, early S15 versions came standard with just 1366 x 768 pixel resolution and a 1920 x 1080 option (and 1366 x 768 pixel is still the default for a number of rugged laptops). That's too coarse for a 15.6-inch screen, and we're glad the S15 comes standard with 1920 x 1080.

Display resolution, of course, isn't everything. Most semi-rugged notebooks, including the S15, will also be used outdoors and sometimes in bright, direct sunlight. Standard transmissive computer displays tend to wash out in daylight, and that's why daylight and sunlight-readability have become important selling points for laptops that will also be used outdoors. That's achieved with various optical treatments to control internal reflection, and also with a strong backlight.

Standard laptop backlights are in the 250 nits luminance range (1 nit = 1 candela per square meter) range, with some reaching into the 300-400 nits range. Industrial monitors used outdoors generally have 400 to 500 nits. High-end rugged notebooks offer anywhere from 500 to almost 1,500 nits. Our review DURABOOK S15 came with the optional 1,000 nits DynaVue™ display; the standard screen is probably in the 500 nits range. In our lab, the S15 display reached maximum luminance of 1033 nits.

A display quality that we consider very important are the horizontal and vertical viewing angles. The DURABOOK S15 display has near perfect horizontal and vertical viewing angles, and is a definite improvement over the last S15 we tested that was still affected by chromatic aberrations and color shifting as you changed the vertical viewing angle. That makes a BIG difference.

Glossy displays continue to rule in consumer notebooks and tablets because they "pop" indoors and in environments with few reflections, but matte or semi-matte displays can be better outdoors where they diffuse light in a controlled manner, making it easier to view them under the typically high-contrast outdoor lighting conditions.

We appreciate that the S15 display surface is semi-matte rather than the high gloss of most consumer notebooks. That means fewer harsh, distracting reflections outdoor. However, since matte displays diffuse rather then reflect light, they can appear slightly muted/softened when viewed from certain angles. As is, overal what we can report is that the S15's display is looks great, with vibrant colors, and thew 1000 nits version we tested is definitely bright enough for just about any outdoor use.

How rugged is the DURABOOK S15?

The well-chosen "DURABOOK" brand name invokes connotations such as "tough," "durable," "reliable" and, well, "rugged", even though the S15 is technically a "semi-rugged" design and the company refer to it as such. There are no official standards on what, exactly, defines "rugged" or "semi-rugged" or even "durable" or "business-rugged" or whatever else the industry has come up with. Even the often cited MIL-STD-810H military testing standard really only describes procedures for a variety of environmental and durability tests. As far as we're concerned, "rugged" machines are fully sealed against the elements, "semi-rugged" ones aren't. And rugged gear generally uses heavier construction and materials, and is specifically designed to hold up against a larger number of environmental and operational threats.

As is, the DURABOOK S15 spec sheet claims MIL-STD-810H certification for having passed drop, shock, vibration, dust, altitude, high/low temperature and humidity tests.

What exactly that all means requires a detailed look at every single test the unit has passed in a ruggedness testing lab, what the parameters were, and what version the version of the MIL-STD used for the tests requires. For example, as is, the original S15 only claimed resistance to a 2-1/2-foot drop, the 2019 predecessor of the current unit, claimed a 3-foot drop, and this latest version a very respectable 4-foot drop.

The difference between 2-1/2 feet and 4 feet is substantial. 2-1/2 feet means falling off a desk. 4 feet means dropping it from chest hight walking in the field. What changed? The switch from rotating hard disks to solid state memory doubtlessly made units less prone to failure. Materials have changed, designs, and the company has more and more experience.

For vibration resistance — which is a very important factor in vehicle-mounted deployments — the S15 passed the testing per MIL-STD-810H, Method 514.8, Table 514.8C-I, Category 4 — Common carrier, 2 hours/axis, operating which tests resistance to vibration using standard laboratory shakers, slip tables, and fixtures.

On the sealing front, the DURABOOK S15 still rates an IP5X, where the "5" means the device is protected against dust, but with limited, non-harmful deposits permitted. The "X" says there is no rating indicating protection against liquids. What this means is that instead of water-proofing the entire housing, which requires a heavier, more complex and more costly design, the company concentrated on spill resistance, which is usually the primary source of damage through liquids. That said, some of the semi-rugged competition now claims IP53, where the 3 stands for being able to handle water spray from top.

The ability to operate in very high and very low temperatures matters in rugged laptops. Here, the S15 claims a very wide range from -4F to 140F. That covers commercial freezers all the way up to higher than the hottest day ever recorded in Death Valley.

What it boils down to is that the S15 is way more damage-resistant than any consumer or enterprise laptop, but it's not waterproof like a fully rugged laptop and can't quite take the same abuse.

Summary: The DURABOOK S15

The DURABOOK S15 is the latest, most powerful, and most technologically advanced version of a well established line of semi-rugged laptops from one of the industry's most respected and most experienced designers and manufacturers of military-grade mobile computing products.

Weighing in at a manageable 5.7 pounds, the S15 is just 1.16 inches thick. It can still be ordered with an internal optical drive, comes with extensive onboard connectivity, and has a nicely integrated carry handle. Built around a very solid magnesium alloy chassis, the S15 presents a high-quality look and feel.

This latest version of the DURABOOK S15 brings a very substantial performance increase via a full four genereration leap from Intel's 8th to 12th generation of Core processors. Add to that a switch to ultra-fast PCIe NVMe solid state disk and DDR5 RAM, and we're talking a very quick machine with state-of-the-art performance.

The DURABOOK S15 has a large 15.6-inch 16:9 aspect ratio display with full 1920 x 1080 pixel HD resolution that remains usable outdoors without much reflection and glare. There is no touch screen. The display surface is semi-matte, which makes it more pleasant to use than a glossy screen. The display has near 180 degree horizontal and vertical viewing angles. With the 1000 nits Dynavue option, the display is very bright.

Even though the DURABOOK S15 is a semi-rugged and not fully rugged design, it is an exceptionally well constructed machine. Its magnesium alloy chassis should hold up for a long time, and there is plenty of shock-mounting as well as lots of internal protection. However, while the unit can handle spills onto its keyboard and such, it is not waterproof (there are open cooling vents to inside on side and bottom).

With its — for a full-size semi-rugged design — remarkably light and slender design and build, the DURABOOK S15 represents a contemporary laptop computer that offers both very good performance and exceptional value. And it comes in an elegant, attractive package that's significantly tougher than standard consumer laptops and should hold up well in daily use. -- Conrad H. Blickenstorfer, November 2023