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COROS’s Nifty New Keychain Watch Charger: Way more detail than you needed


As longtime readers know, I’ve probably got a bit of a watch charging ‘thing’. One might call it an unhealthy obsession with creative ways to charge a watch, another might call it a fetish. However, what is clear is I’ve got a lot of watches to charge, a lot of the time, and I am always looking for creative solutions to charge a watch.

In most cases, these creative solutions are not from the company itself. For example, there’s the $9 twofer Garmin puck charger I wrote about, or that time I bought pretty much every type of Apple Watch charger I could find on Amazon (I haven’t quite written about that yet, but research is going well). These solutions are almost universally better than what the companies make themselves, primarily because they’re almost universally cheaper.

In any event, COROS’s big news today is some training load and recovery stuffs. And that’s all fine and dandy. But what I’m here for is the charging cable keychain. Did I mention it’s red, titanium-looking silver, and black?

Yup, we don’t even need to test whether or not this thing works – it’s already a winner in my book. Though, the $25 price tag is a bit…umm…pricey.

The Keychain:

The device is relatively simple, and has two pieces that detach from each other. First, there’s the charger shell, which stays affixed to your keychain:


Then, there’s the charging cable guts, which pops out of the shell when you press the side button, revealing the nylon cable with a standard USB port on one side, and the three-pole COROS charging port design on the other:


The USB cable side is a naked USB plug design, meaning that it doesn’t have a secondary shell around it. We’ve seen this before from various companies in the sports tech space, including Polar, Nike, and I think even TomTom. It works just like a regular USB plug, except..well…naked of a case.


On the COROS side, this pops into any COROS watch, which all use the same three-pole attachment system. The fit was snug, but not overly crispy either.


The entire cable length is essentially the same length as the bottom of the band to the top of the watch body:

P1022374 P1022384

Charging is at the normal speed, no differences there.


And with that, this review is done. Seriously, there’s nothing left to do except stick it back in its home:


(Side note: I feel this post would be incomplete if I didn’t mention some black magic that COROS did with respect to shipping this a few weeks ago. They e-mailed me at 10:32PM on a Friday night European time, confirming my address in Amsterdam. Then, on Monday morning at 8:52AM, the box arrived by my always prompt UPS man from China. I mean, the box was shipped from China, not the UPS man. He’s very much Dutch. And also very much perplexed at the wide assortment of massive and tiny boxes he has to drop off each morning, as the first stop on his route. In any event, how is it that COROS can manage to get a box shipped 9,234km on a weekend is beyond me.)



I don’t really have any further wrap-up text, but the way the site works, it’s handy if I have a bulleted section at the end. Thus, I’m compelled to write some text here. But realistically, you’re probably still back thinking about that Wrecking Ball.

In the meantime, I’m off to order one of these for my permanent collection.

With that, thanks for reading!

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Hopefully you found this review useful. At the end of the day, I’m an athlete just like you looking for the most detail possible on a new purchase – so my review is written from the standpoint of how I used the device. The reviews generally take a lot of hours to put together, so it’s a fair bit of work (and labor of love). As you probably noticed by looking below, I also take time to answer all the questions posted in the comments – and there’s quite a bit of detail in there as well.

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  1. SB

    This would be awesome if the shell was also a battery give an on the go top up for the watch in a pinch.

    • Juan

      haha, that’s what i said!

    • SB

      I actually thought that’s what it was at first glance before reading the article.

    • Tyler

      Yeah, I thought that was what this was at first, also.

      A slightly shorter cable seems pointless.
      Also, if you are concerned about portability, who is carrying a giant keyring these days?

      Nearly all cars made in the last decade have a small key fob; some are accessible via your phone alone. And homes are increasingly accessible digitally.

      A small battery charger and cable combo that you can carry with you on the bike for a day+ long tour – now that would be worth something.

  2. Juan

    Want to make this product better? Have that metal piece be a small battery where it charges a small percentage of your watch. Right now its just a pointless cable/keychain

  3. Henrik

    What, a review without the unboxing section? No size/weight comparison with an Oreo cookie? 🙂

  4. David

    That is brilliant.

  5. Dave

    Is there anything equivalent for Garnin watches?

    (Yes I already have the puck chargers)

  6. Thomas

    Do you any indication that they actually sent it after sending the email to you? They could have mailed it weeks before and just have woken up Friday night thinking “Did we get the address right?”

    • Yeah, they shot me the UPS tracking number. It’s pretty incredible how fast they can move. Like, some poor guy must live at the UPS depot in Dongguan, waiting for this moment and a portable shipping label printer.

  7. Christopher L Bosch

    Do those Garmin puck chargers actually work for you? They are neat, to be sure, but I’ve ordered them twice and all four that I now own usually won’t charge my Fenix 6x Pro or my wife’s Forerunner 745.

    Random additional question I’ve had on my mind for a while and may as well throw in here since I’m already typing… Apologies for being off topic. I haven’t found a recent review on Stages left-only crank arm power meters on your site (not sure if the one from 2013 is still valid), but I think I’ve seen a few comments hinting you don’t think too much of them. I got one not too long ago, and it usually reads 25% or more lower than my Wahoo Kickr Snap. Is that… A normal amount of bad for this type of power meter? Wondering whether I have a faulty product or just a crappy one that works as well as any other would. Garmin routinely thinks my fitness is cratering whenever I go for an outdoor ride, and I’m really regretting buying it, even though it was cheap. I have done zero resets before rides, but it doesn’t seem to make a difference so I typically do not bother.

    • That’s wonky – definitely, both my wife and I use them to charge virtually everything Garmin these days. I’ve got ones in the kitchen, shed, bedroom (both sides of our bed), office, bag, etc… I bought a lot of them, all perfect.

      As for a left-only power meter, 25% is pretty low – like, crazy low. Something there is faulty, though, figuring out if it’s the SNAP or Stages will be tough. Any chance you’ve got a friend with a bike and a power meter to put on the SNAP (remember to calibrate after 10 mins first).

    • Christopher Bosch

      I’ll see if I can convince one of my friends to try it, but I’ve ridden several other stationary bikes with power meters from Matrix and Stages, so I have a pretty good idea of what kind of power I can produce, and I don’t believe the issue is the SNAP. I can’t compare those to the SNAP directly, of course, the way I can the Stages, but based on RPE, ramp tests, average wattage after a ride, etc., I’d say the SNAP is a hair lower than the stationary bikes, no more than 10%. I only calibrate the SNAP maybe once a month, but I’m really careful about keeping my tire pressure consistent and I have a mark on the knob to keep it consistent as well.

      I’ll see if I can get my bike shop to test it for me next time I have it in, maybe.

    • John

      They’ve never worked for me. Been through two packs already. Not sure I’ll take a chance on a third.

  8. Bruce Burkhalter

    You cover this but not the new GoPro 3-Way 2.0 stick??? When I wake up tomorrow, there better be a 10,000 word review and 40 pictures of it or I’m asking for my $20 back! 🙂

    • Yeah, I know – I’ve had it for a month now, and just need to get around to getting a video/post out on it. It’s great (mostly).

    • Bruce Burkhalter

      Hopefully you know I’m joking! I’m sure you have a ton of stuff on the docket ahead of this. The ball swivel looks nice, though.

  9. Giles Roadnight

    It’s not a charger… It’s a convenient place to keep a charging CABLE!!

    • usr

      True, but USB to proprietary adapters are a common bottleneck, availability of USB rarely is. If you travel internationally, USB is the only socket you can expect everywhere.

      (Funny how these days, “if you travel internationally” almost feels as irreal as “if you routinely find yourself harassed by balrogs on your trips to Mordor”)

  10. Johan

    In the third picture from the bottom, it kinda looks like the connector at the watch end is coming apart. What’s going on there?

    • Yeah, I somehow pulled it apart and then put it back together. Apparently in that photo it wasn’t snapped all the way back together again. My understanding is that this one is technically pre-prod, and I suspect might have been missing a dab of glue inside that connector. 🙂

  11. Martin Winson

    You seem to be the only person with anything good to say about UPS. Take a look at “trustpilot” and see after 16,529 reviews they are given just one star (zero stars is not available). They have not responded to negative reviews in the last 12 months. Personally I waited three weeks for my Gopro stuck in one of their warehouses. Avoid at all costs.

    • Yeah, I guess I just have lived in enough places around the world and gotten/sent more packages than the average bear, in more countries than the average bear, to know that for the most part all these services are the same.

      They have sucky locales, and good locales. Sucky days and good days. Largely, it depends on your exact location.

      UPS for me is very strong for delivery and pickup. I’m literally their first stop every day from the airport, and I can predict within 2-5 minutes when they’ll arrive (8:50-8:52 most days, including today again). Meanwhile, UPS for me sucked horribly in Paris. To use your GoPro example, when I order GoPro stuff from GoPro’s Europe site, it literally shows up every single time the next morning. Flawlessly.

      FedEx here is great once it gets on a truck (the guy is super friendly). But between the point it lands in this country and the point it gets on his truck is generally a disaster, most times. As is scheduling a pickup (as there are no FedEx locations in Amsterdam city, nor any FedEx drop boxes in the city). I had a Wahoo KICKR Bike stuff for 3 weeks in a FedEx customs cage. I spent the last nearly two weeks on failed scheduled pickups of other gear going back. Inversely, for the most part FedEx in Paris was great – or at least functional.

      DHL is fine, when it wants to be. There’s so much DHL here that it somewhat comes down to the driver, which varies constantly. But it’s also silly easy for me to find a DHL driver by just pedaling around the block, one will be somewhere. And customs is literally never an issue. Inversely, DHL in the US when I lived there was a nightmare. Maybe it’s improved.

      And ultimately, it just comes down to knowing that for every person that says UPS is horrible, there’s another that says FedEx is horrible. Or that DHL is horrible. Or that the inverse of any one of those is great.

  12. Mr T

    I think it’s unfortunate that they didn’t make a flatter connection. So you could charge it on the go.

  13. Thadd

    I don’t get this. The Coros watches come with a small cable already. Their major selling point is that they have batteries that last forever. This seems to be the least necessary addon ever.

    • The point of this is that it’s attached to your keychain, so you always have it. The idea being when you travel, it’s there. Versus getting where you’re going and trying to find a COROS cable.

  14. IvanDobski

    Is there any legitimate reason why (none Apple) manufacturers don’t just use USB-C? I had a Sony Smartwatch which used USB for charging and a couple of reviews had this as a con but for me it was possibly the best feature of the watch – I could charge it anywhere with no special chargers etc required.

    • Yup: Waterproofing.

      That’s it. And unfortunately, it’s a huge one. While there are waterproof USB-C ports, all of them are basically only IPX7 waterproofed (so 1 meter at 30 mins), and not good enough for watches to support deeper waterproof connections.

      We saw Polar try a few years back with one of their mid-range watches to do a micro-USB port that was theoretically waterproofed to 50m. It was mostly a disaster.

      The problem is, you’ll undoubtedly find a company selling a waterproof USB-C port to 50m or 100m or such. They’ll float around CES with their little acquarium demos and such. But none of these demos handle well what endurance athletes do to watches. On the whole, endurance athletes are a dirty, messy bunch (myself included). Our wrists are covered in sweat, dried salt (from ourselves and oceans), sometimes mud from roadways or trails, gels and nutrition drinks gone poorly, and who knows what else. All of that ends up in that port, dries, gets crunched up…and then repeat that 300 times. Little rubber covers never really work either.

      Ultimately, the goal would be wireless charging using the various standards. But even that has significant downsides in terms of being able to access the watch directly if you wanted to.

    • okrunner

      Motoactv. Need I say more. Use of USB killed one of the most revolutionary gps watches ever. Motorola could have owned the market but for the use of USB.

    • Eli

      Size is a big factor too as the connector that would need to be in the watch is about 2.2×8.2x9mm And structurally attached to the PCB board. That cuts into space for the battery and means the pcb has to be structural. Notice how all the wired watch adaptors are structurally dependent on the case of the watch.

  15. Michael

    Thanks for the review! For anyone counting grams, I just got my keychain charger and weighed it. The weight comes in at 4 grams for the cable itself, or 14 grams for the cable+accessories (cable, cover, lanyard, ring). Compare to 20 grams (and 3x bulkier) for the cable that came with my watch. Compare to 50 g for a 2500 mAh Li-ion battery (18650 size). While I’m measuring things, the length of the keychain charger is 6.5″, whereas the original cable is 22″ long. I’ll be leaving the original cable at home!

  16. CV

    This is a poor defective design. I just received it new today and the plastic cover that is supposed to hold the cable does not. The plastic clip is flimsy cheap plastic and will not click back in so the cable is not held in place. If you use this as a key chain or hanging anywhere, you’re guaranteed to wind up with a lost charging cable leaving you with an empty plastic shell on your key chain.

    • Steve

      I’m a little disappointed with the design too. I expected the cable to solidly “click” into place instead of just sliding loosely into the plastic shell. The red cable has already slipped out from its holder a couple of times. Nice idea, shame about the finished product.

    • Steve

      I contacted COROS about the poor fit of the cable inside the clip. They asked for a short video showing the issue and agreed my unit was defective. They sent out a replacement via FedEx which I received 2 days later. New unit works great. Impressed with the customer service too!

    • CV

      I also contacted them, sent the short video and received a replacement.