Garmin Fenix 7 Pro & Epix Pro Battery Charging Times: Interestingly Different Results

Over a year ago, when the original Fenix 7 & Epix came out, I went down a stupid rabbit hole of seeing exactly how long it took to charge each of the models. Except, I overdid all of this. Building a charging station, ensuring I captured the exact charging amounts every 10 minutes, ensuring all units were at the same levels, etc… In theory, it sounds simple, but in practice, something always goes wrong. I never got around to publishing the video or post on it because my data set wasn’t fully complete. This time though, with the Pro units, I’ve succeeded!

This is most interesting though because last time all Fenix 7 and Epix units basically charged at exactly the same rate. Like, crazy-same rate. It was both silly and slow. Basically, they took 1hr 45 minutes to get to 90%, and then trickle-charged from there to 100% over the next hour, arriving by roughly 2 hours and 45 minutes. By far, the slowest-charging watches that I know of. To begin, here’s the chart of the existing/original Fenix 7 & Epix units. I had tested the Vertix 2 at the same time, hence why it’s in there:

Now, as you can see, all three Fenix units (different sizes) actually arrived at their battery fullness levels at virtually the same time (with the Epix too). Given they all have different battery sizes, that’s a clear indicator Garmin engineered these units to have identical charging times. The initial product design spec said “Go Really Slow” and that achievement was unlocked.

Now fast forward 15 or so months and I started testing the Epix Pro. I immediately noticed how darn quickly the Epix Pro (47mm) charged. It was roughly in the 1hr ballpark to the 90% level, which was really good – on par with what Garmin does on some of their Forerunner 955/965 & Venu 2 lines that have charging times in the hour range. From the 90% level, like most devices, it trickle-charges from there to top-up. This keeps the battery healthy.

But that was then followed by the realization that the Fenix 7 Pro did not share this new-fangled faster charging. In fact, upon discovering this, I drained down batteries and re-charged again with different chargers, thinking I had screwed up somehow. I even went back to Garmin to triple-check I wasn’t somehow plugging the cable in wrong. But no, they confirmed that “due to hardware differences, Fenix and Epix do indeed charge at different speeds.”

(For technical geekery purposes: All these charging tests were connected to vastly overpowered high-speed USB charging hubs, where the per-port and total bandwidth of each hub was a multiplier more than these watches could ever pull – more geekery down below).

So, I set up this whole stupid setup again this past weekend at home on my workbench, and got to town. I use the cheap 2-for-$9 Garmin charging pucks (review here), which I tested side by side also over with regular new Garmin USB-C charging cables and found zero difference in charging times. All results are taken +/- 30 seconds at a 10-minute interval. With the Fenix 7 units being always-on displays, I can use a camera and check results. But for the Epix units, I had to go and tap the screen every 10 minutes to see the battery state.

Here’s a graph of the Epix Pro & Fenix 7 Pro together, based on my test results.:

There are a couple things of interesting note here:

A) Epix Pro Got Fast Charging: Most obviously, the Epix Pro series is faster than before (almost twice as fast to 90%), however, the largest Epix Pro (51mm) isn’t quite as fast. That unit uses the even-larger Enduro 2 battery (larger than the Fenix 7X Pro battery). Thus, I suppose that’s the biggest straw-pipe they could charge it with.

B) Fenix 7 Pro Got Slightly Faster: Interestingly, while the Fenix 7 Pro is still slow charging in comparison to the Epix Pro, it’s actually faster than it was before. When I compare how long it takes to get from 0 to 20%, it took about 25 minutes on the original Fenix 7 units, and now about 20 minutes. So it is indeed slightly faster.

C) They are no longer in lock-step: Specifically, in my previous testing, all three Fenix units charged scary-identically at the same rate. However, now we see the Fenix 7S Pro charge slightly faster. I don’t know if this was a weird charging quirk in my test or whatever, but I thought it interesting.

Now, one funny aside here is actually trying to kill all these watches. By themselves, all six units have quite a long battery life, so charging every day isn’t something you have to do. Thus, what’s the best way to efficiently drain the battery down? The flashlight my friends. Combined with turning on GPS, but staying indoors. I’d turn on the flashlight at full brightness, then turn on GPS and put it somewhere inside that doesn’t get GPS signal. That causes the GPS receiver to require even more power, and ensures that it forces to multiband too.

I could have also played music, but I was too lazy to get six different sets of headphones paired up to them. It’d taken me more time to charge up that many pairs of headphones, than just turn all the watches flashlights and GPS on, and let ‘er burn. I don’t have exact times on how long it takes to kill off the battery on each one because most of them started in the 20-40% battery range. But I’d guess the combination of both of those things would do it with a full battery in under a few hours. I have not tried testing how long the flashlight lasts from full charge (no blocked GPS on). If you have a new unit and are sufficiently bored, feel free to charge it up and then leave the flashlight on full and drop the results in the comments.

Now, one more curious thing is whether or not these watches changed their charging rate (power draw). For that, I’ve got the little $29 USB-C meter, which measures the USB power draw. This one is USB-C enabled, and is specifically the super-high wattage variant that can even measure high-wattage laptops up to 240w. Overkill for our purposes here, but useful for testing other high-wattage things (and also a general note if you buy one, just make sure you get the newer high-wattage one I linked).

From a power draw standpoint, the Epix Pro units, when charging below 90%, have a power draw as below (measured while the unit was charging between the 20% and 60% markers, as to not run afoul of trickle charging at the top-end), all with a voltage of 5.12v plugged into a high-capacity 30w charger, and I let all of them stabilize for a minute:

Epix Pro 42mm: 0.24a @ 1.17w
Epix Pro 47mm: 0.35a @ 1.79w
Epix Pro 51mm: 0.45a @ 2.30w
Fenix 7S Pro: [To be added later, travelling this week and didn’t bring it]
Fenix 7 Pro: 0.17a @ 0.87w
Fenix 7X Pro: 0.27a @ 1.38w
Forerunner 965 (just cause): 0.41a @ 2.09w

Meanwhile, there are the previous version power draw numbers, for the units I have with me while travelling, which is a quantity that greatly upset the Dutch TSA equivalent on Sunday:

Epix not-Pro: 0.18a @ 0.92w
Fenix 7 not-Pro: 0.18a @ 0.92w
Tactix 7: 0.28a @ 1.43w
Enduro 2: 0.45a @ 2.30w (notably same as Epix Pro 51mm)

Lastly, I don’t know what the battery sizes are yet in mAh. The USB charging plug doesn’t measure that…so…yeah. Perhaps it’s listed on a spec sheet somewhere I haven’t seen.

With that, our geekery is over – thanks for reading!