Dell Latitude 7390 2-In-1 Review: A Convertible Built For Business

In the following benchmarks we employ two very different battery life tests, Battery Eater Pro and a custom 1080p HD video loop test developed in-house, to prove out battery life with our test group of machines. In all tests, Windows 10 Quiet Hours has been enabled and the displays are calibrated with lux meters on pure white screens to as close to 115 lux as possible. For the average laptop this is somewhere between a 40 - 60% brightness setting. Since laptop displays significantly affect power consumption and battery life, it's important to ensure a level playing field with respect to brightness of the display for battery testing. However, since many laptop displays vary in brightness at each respective setting in Windows, this calibration with the meter is critical to ensure all displays are set to as near identical brightness as possible before testing.

Battery Life - How We Test:

Our custom HotHardware video loop test takes a 1080p HD video with a 16Kbps bit rate and loops it repeatedly, with 1 minute break intervals in between. A timer log file increments minutes of up-time every minute -- along with the grand total -- before system shutdown is stored in the log. This is a lighter-duty test that is still a bit more strenuous than many office productivity tasks, but it's not nearly a taxing as the load Battery Eater puts on a system.

The Latitude’s 60Wh battery holds its own here with one of our best runtimes from any notebook we’ve tested. The more premium XPS 13 still outpaces it, but only by a narrow margin. For those seeking a notebook to get them through the workday grind, the Latitude is certainly a contender.

Battery Eater Pro wears a machine down much more quickly by placing a heavy load on all laptop subsystems, including processor, graphics, memory and even some file transfers to storage. This is truly a worst-case test that will give you a sense of how a machine will hold up under heavy strain, when under taxing, continuous content creation workloads, for example.


Dropping the pedal to the metal is a less forgiving for our Latitude. Compared with the XPS models, we see the Latitude last less than half as long despite relatively similar results in the video loop test. We suspect this is in part due to the less efficient cooling setup which necessarily works the fan harder to remain cool. Additionally, we don’t know the relative efficiencies of the displays although the similar video loop results suggest it is not a significant factor.

If you need a notebook for heavy duty workloads, such as rendering on the go, then you may be better served with a notebook that scores higher in the Battery Eater test. However, for regular light-duty usage, the Latitude 7390 2-in-1 is more than capable of lasting all day.
That’s not quite the end of the story though. Dell also provided us with their 45W Hybrid Power adapter. Unlike most power bricks, this one houses its own 43Wh lithium battery to keep your notebook juiced on the go. As a nice bonus, it also provides an extra USB-A port to power up your phone or other devices.

The Hybrid Power adapter is substantially larger than the included standard adapter, but even so it is still smaller than the adapters many competing notebooks ship with. The extra functionality spares us from carrying yet another power bank on long hauls, so we really don’t mind the extra heft, especially when the upper black portion disconnects when you do not need to charge it. As a side note, our early production Latitude did require a BIOS update out of the box to recognize the adapter -- not a big deal.
We wish we could adequately test the extra run time, but the charging status prevents our battery benchmarks from running. Depending on usage, we might expect this to extend battery life by one to four hours. For practical usage, it provides enough current on battery to keep the notebook topped off, even under load. It is pricey though at around $137, so it may be worth checking into third party solutions before committing.

In terms of acoustics, the Dell Latitude 7390 2-in-1 is mostly a quiet machine until it comes under load. The small fan ramps up quickly when the machine is being taxed, as it attempts to keep thermals in check, and emits a high-frequency whine. The fan also kicks in occasionally while the lid is closed and the system is sleeping which may contribute to reduced standby power. Overall though, during day-to-day computing tasks, this new Dell hybrid machine is unobtrusive and we wouldn't consider it loud by any means.