Replacing a Garmin Forerunner 15 watch

Unsurprisingly, I've been doing a lot more exercise outdoors this year than last, including a lot more running. So I've had a lot more time to try out the Garmin Forerunner 35 GPS watch I've had since the end of 2019.

I have owned a Garmin Forerunner 15 watch for a few years and, especially considering what it cost, it served me well. The main issue with it was that the battery life seemed to have deteriorated over its lifetime. Changing the battery isn't too complex a procedure — there are YouTube videos that show you how — but since the battery life was never that great from new, it seemed worthwhile looking into getting a different watch. And late last year, I saw an offer on a Garmin Forerunner 35. The Forerunner 35, like the Forerunner 15, is again an entry-level GPS watch, but it's a considerable upgrade from the Forerunner 15.

Comparing the Forerunner 35 to the Forerunner 15

Though the Forerunner 35 is comparably priced to what the Forerunner 15 cost when I bought it, there are a number of improvements and extra features of the Forerunner 35 over the Forerunner 15.

The Forerunner 35 is a less chunky, and more subdued design than the Forerunner 15 — looking around, there's a Forerunner 25 that looks like an odd hybrid of the 15 and 35 designs — and has walking and outdoor cycling modes. The screen on the 35 is also higher resolution. There's a built-in wrist heart rate monitor. I'm not entirely sure the heart rate measurement is always that accurate, but it removes the need for an external sensor, if a rough idea of heart rate is what you want. The backlight is also an improvement over the Forerunner 15. There's also the option to pair a phone via Bluetooth, though that's not something I've bothered to use.

On using the 35, the battery life does seem much improved over the 15. I never wore the Forerunner 15 daily, only for runs. By contrast, I'm wearing the Forerunner 35 I've used daily: it does need a charge every week or so, but that doesn't usually take long. Even if low on power, you can give it a quick boost before you head out and it will probably tide you over for your run. With the Forerunner 15, there were numerous times where I found it would run out of battery on longer runs.

Using the Forerunner 35 on Linux

Much like the old Forerunner 15, this watch still works fairly well even if you're not using Garmin's own software. That might be because you're not keen on sharing your data or because you're on Linux and can't easily run the software; the Windows version may run with WINE, however.

Even if you don't use Garmin Connect, the watch gives you access to everything you need as it appears as a USB storage device. You can retrieve and apply GPS updates by other means; without a regular update, GPS locking can be slow and take several minutes, as it did with the Forerunner 15. It's also straightforward to copy the Garmin .FIT files from the watch and convert them to .gpx with GPSBabel or similar.


The two things that usually fail on digital watches are the strap and the battery. The Forerunner 35 has a reasonably durable strap. And the strap's replaceable: you can at least buy third-party replacements. The battery is another matter: Garmin don't want you to replace the battery in any of their watches at all — and I can't find any posts or videos on doing so for the 35. However, if the Forerunner 35 is built like the Forerunner 15, a battery replacement could be possible if you're willing to take the watch apart.

The battery replacement issue is one reason why I'm not inclined to spend much more on specialist watches. You can easily spend two to four times as much as the Forerunner 35 costs on more expensive Garmin watches. I'm not sure how much value you get for spending more. For me, the only significant features missing from this watch are directions to follow a GPX route, and a swim mode. (That said, the Forerunner 35, like the Forerunner 15, is waterproof). Neither of those omissions are enough for me to spend considerably more. My primary use is tracking pacing and distance while running, and the Forerunner 35 does well here.


Whether you're looking at replacing an older, budget running watch, or you've not ever had such a watch and want to try one out without spending too much, the Forerunner 35 is a quietly competent choice. It's been a substantial upgrade from the Forerunner 15, which I also liked a lot.