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Diesel On Full Guard 2.5 review

Diesel On Full Guard 2.5 watch has killer looks but deadly battery life

Diesel On Full Guard 2.5 review
Diesel On Full Guard 2.5
MSRP $325.00
“Terrible battery life and slow performance kills our enthusiasm for the striking Diesel On Full Guard 2.5.”
  • Striking design
  • High resolution, bright screen
  • Terrible battery life
  • Slow performance
  • Diesel apps can frustrate

I’m going to start with a disclaimer: I like Diesel watches. The big, bold, take-no-prisoners designs are unique, and instantly recognizable on your wrist. The sheer size of most means you can’t miss someone wearing one either. I always hold a special kind of admiration for anyone I see wearing a Mr. Daddy 2.0 Diesel watch, all 57mm of it.

Does that mean the Diesel On Full Guard 2.5 gets a pass, and is already on its way to an easy win here? No, quite the opposite. I hold Diesel to a high standard, and its smartwatch running Google’s Wear OS platform needs to meet this if it’s going to impress. Sadly, while Diesel holds its end of the deal up, it’s let down by the battery and underlying technology.

Big and bold

Yes, the On Full Guard 2.5 is large, but at 47mm it’s quite compact by Diesel’s standards and also surprisingly slim at 13mm — an aspect emphasized by the clever design. The bezel is angled inwards towards the screen, and the four guard pieces minimize the visual size of the watch. You know when it’s on your wrist, obviously, but it’s not heavy and isn’t ungainly either. Provided you are used to large watches and don’t have very slim wrists, you’ll be happy wearing the On Full Guard 2.5.

The red and black color scheme seen in the photos is our pick, although you can get a black and steel finish too. These both have the knurled case feature seen on some of the recent traditional Diesel watches, which are also added to the surroundings of the buttons and the crown. The lugs are pretty, with swoops and curves giving them a modern, thoughtful style. All this gives the watch character — a striking, statement-making character that’s modern, masculine, and immediately identifiable as a Diesel watch. I think it looks fantastic.

Modern, masculine, and immediately identifiable as a Diesel watch. I think it looks fantastic.

My review model has a quick-release silicone strap attached, although you can buy leather and metal versions too. It’s a thick, tough silicone that is very pliant. The underside has a grippy texture that helps keep the watch in place, and resist sweat. It’s extremely comfortable, but it attracts lint and dirt like nothing else. Five seconds under the sleeve of my hoodie and it came out covered in the stuff. The ridges on the strap, and the embossed Diesel brand name on the keeper, make it hard to brush it all away, ensuring it always looks a bit dusty.

This aside, what makes me like the Diesel On Full Guard 2.5 the most is that it doesn’t look like any other smartwatch. It’s obviously a Diesel, giving it plenty of appeal to brand aficionados. Watches are as much a personal fashion and lifestyle statement as a pair of sneakers or your eyewear, so settling for a faceless smartwatch shouldn’t be necessary.

Software and performance

Look at the On Full Guard 2.5 from a distance, and it’s great. Actually use the watch, and things take a turn for the annoying. Then they take a turn for the tragic, which we’ll come to later. The annoyance comes from the often pitiful performance from the Qualcomm Snapdragon 2100 processor with 512MB of RAM, and Google’s Wear OS software.

Evidence on how hard the chip has to work comes right from the start. Setup is such a lengthy, stutter-filled, plodding experience that I never want to pair the watch with another phone again. Things do improve after it has finished setting up and updated the software, but it’s still not as smooth and seamless as the Apple Watch Series 4, or Tizen on the Galaxy Watch.

Diesel On Full Guard 2.5 review
Andy Boxall/Digital Trends

The Snapdragon 2100 is old, and has been replaced since the On Full Guard 2.5 launched. I complained about its presence when the watch was revealed in September 2018, and time has not been kind. Even cheap smartphones have substantial performance today, and using a smartwatch that can’t match the zippiness of even the cheapest of modern mobiles is frustrating.

Navigation around Wear OS is helped by twisting the crown, but this only operates up and down, and not left or right, so you still have to swipe the screen to access Google Fit, Google Assistant, or other Tiles. Do any of these swipes too fast, launch too many apps, or make some heavy demands, and things slow down. Leave the watch on the always-on screen for too long, and it’s an extra second or so to wake up the display. None of this stops the watch working, it just feels, well, old. Start trying out Diesel’s own apps, and it gets worse.

T-On-I is a kind of virtual assistant without the voice, and it displays helpful content — reminders, calendar entries, and step count for example — apparently in a Diesel-like manner. Crime number one is that it’s slow, and crime number two is it doesn’t work very well. It’s slow to the point where it will lock the watch up, it never recorded my steps, and the stupid phrases it occasionally delivers border on the moronic. “Oh hello smartphone, guess who’s got all the attention now?” is an example, which it shows over the main screen. Getting rid of it seems to take swipes and button presses.

The battery life on the Diesel On Full Guard 2.5 isn’t just bad, it’s tragic.

You can customize the watch face with overlays related to the weather or your activity. The weather layer adds raindrops, a lightning bolt, or other effects over the face, for a quick-glance weather report. This is fine if the weather is interesting, but I live in England where it is permanently cloudy, therefore the face has a mist over the top and it’s not especially pretty. It’s a shame, as Diesel has worked hard on the included watch faces — each of which resembles the crazy ones you see on a normal Diesel watch, and covering them up is a crime. The Dashboard, D3000, and Flicker faces are all great.

I wore the Diesel watch linked to a Huawei P30 Pro, and with an Honor 20. It worked the same way across both phones. If you link it to an iPhone, various features — from the Play Store to Google Assistant — will not operate. Notifications are generally effective, but often I would receive a vibrate alert for the same messages over and over again, while others — messaging app Line, for example — sometimes wouldn’t appear at all.

Positives? The vibration alert is strong and can’t be missed, the 1.39-inch AMOLED screen is big, high resolution, and bright, while Google Assistant is smart, helpful, and just a swipe away from the watch face. If you use Google’s tools extensively — it shows your calendar, appointments, and pulls information from Gmail, and Google Maps too — then it is a great feature.

Fitness tracking

Google Fit is the standard fitness tracking app on the Diesel smartwatch, and it’s a comprehensive, simple to use workout companion for the average person. It’s accessed with a left swipe on the home screen where you can instantly see step count and other metrics. Fit’s Heart Points only accumulate if you activate the watch’s heart rate monitoring though, and that’s not good for the battery life.

Interacting with Google Fit can be a slow process on the On Full Guard 2.5. Going from the home screen to finding a workout plan, let’s say aerobics, and activating it can take minutes to prepare, especially if the Bluetooth connection is weak. The app needs to communicate with your phone, which takes time, and then the slowness of the watch means there are long pauses between screen swaps. It gets even more maddening if the screen turns off while you’re waiting, as that can kick you out and force you to start again.

Diesel On Full Guard 2.5 review
Andy Boxall/Digital Trends

Once you’re going, it’s great. There are many pre-made workout tracking systems, the display provides good at-a-glance information, and all the data is quickly transferred over to your phone. The On Full Guard 2.5 has a heart rate sensor on the back, and the results were in-line with those we got on the treadmill at the gym, suggesting it’s accurate. However, its use does drain the battery, particularly when it’s used continuously, as does the GPS.

Tracking an evening walk, the GPS connected quickly and when used with the phone, rather than on its own, doesn’t have such a detrimental effect on the battery. The battery life drastically limits the On Full Guard’s usefulness as a fitness tracker, which is a shame as not only is it capable, it’s comfortable to wear at the gym too.


The battery life on the Diesel On Full Guard 2.5 isn’t just bad, it’s tragic. A full charge of the 300mAh cell lasts a working day, but no more if you stretch its ability. Start at 9 a.m. and by 7 p.m., the watch regularly showed around 15% remaining even with minimal use, and without any extended fitness features such as heart rate tracking or GPS. Dare to track a one hour workout with Google Fit and the heart rate monitor, and you’ll eat through around 50% battery in one go.

Setup is such a lengthy, stutter-filled, plodding experience I never want to pair the watch with another phone again.

If I purposely didn’t touch the watch and only observed notifications, and turned off the heart rate monitor, then the On Full Guard lasted me throughout the day and needed charging before going to bed. This defeated the point of wearing a smartwatch.

When the watch gets to 10% battery, it automatically turns on the power saver feature, where only the time and date is displayed. Notifications end, and you can’t access any apps unless you turn the feature off. This stretches the remaining time out to several hours, and at least enabled me to still see the time. Recharging the watch is performed by attaching it to a small circular, plastic plinth. It magnetically snaps on the back of the On Full Guard 2.5, and the grip is strong enough that it doesn’t slide off easily. Recharging takes about 75 minutes.

There are very few Wear OS smartwatches with winning battery life, but the On Full Guard 2.5 stands out for being one of the worst I’ve used, and it’s a frustrating downside.

Price, warranty, and availability

The Diesel On Full Guard 2.5 smartwatch costs $325 with the silicone or leather strap, or $350 with the metal link bracelet. In the U.K., the watch costs 320 British pounds with the leather or silicone strap, or 340 pounds for the metal version. If you’re tempted, we love the optional brightly colored, stitched nylon and silicone straps, which cost $40 and are easily swapped on and off to match your outfit or mood. It’s available through Diesel’s own online store, and through Amazon too.

Diesel provides a two-year warranty covering the movement, hands, and dial. It does not cover the battery, strap, case, or crystal, nor will it cover water damage.

Our Take

A striking statement-making smartwatch with looks that could kill, but in reality it’s the battery that dies on a shockingly consistent basis. Those beguiled by the style should also beware of the slow performance.

Is there a better alternative?

If you own an iPhone and are considering a smartwatch, stop reading this and just go and buy an Apple Watch Series 4. It’s the only logical decision, as it works seamlessly with your phone, with excellent software, strong battery life, and a wealth of accessories and straps available for it. It’s the best smartwatch you can buy, and prices start at $400.

If you have an Android phone, we recommend the $255 Fossil Sport which uses the newer Snapdragon 3100 platform and is cheaper than the On Full Guard 2.5, but isn’t as attractive. The $250 Mobvoi TicWatch Pro has great battery life and a clever screen, but the design isn’t inspiring. The $200 TicWatch C2 has better looks, but not the Pro’s clever screen.

Alternatively, take a close look at the $330 Samsung Galaxy Watch if you own a Samsung Android phone in particular, as the design, build and software are all top-notch. The $200 Samsung Galaxy Watch Active is an excellent option as well, but the design is a bit plain. Finally, if long battery life and a design from a mainstream watch manufacturer attracts you, then Casio’s $550 Pro Trek WSD-F30 is expensive but excellent.

How long will it last?

Water resistant to 50 meters, the On Full Guard 2.5 is water resistant so you can swim with it. The body is made from stainless steel and is hard-wearing, and you’d have to treat it very badly to damage it. I’ve worn it daily for around two weeks and despite some knocks and bumps, it still looks perfect.

The watch has Wear OS version 2.6 installed, and the May 1 security patch too. Google keeps Wear OS up to date,but does not release new versions with additional features or design alterations often. The battery inside is the watch’s main limiting factor, and will one day become even less able to hold a charge than it is now.

Should you buy it?

No. The battery life is the Diesel On Full Guard 2.5’s primary drawback, followed by the sluggish performance. Both these add up to a frustrating ownership experience, which puts you off wearing and using the watch. It’s impossible to recommend you splash out at least $325 to own something that will potentially irritate to the point you don’t use it. If you want a Diesel watch, then may I suggest buying a regular Diesel watch, like the new 57mm Mr. Daddy 2.0 with red nylon/silicone strap?

Editors' Recommendations

Andy Boxall
Senior Mobile Writer
Andy is a Senior Writer at Digital Trends, where he concentrates on mobile technology, a subject he has written about for…
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