The only complaint I've had with my 630 since I bought it when it debuted is that in cold temps the watch will shut off unexpectedly. Yesterday, for example, I went for a run in 15F weather with about 75% battery charge and it shut off less than one hour into my run--only to restart and say that it still had 54% battery charge after it warmed back up. I'm now considering upgrading to either the 645 or the 935, and I'm wondering 1) if over the past couple of years Garmin has been able to improve their technology in general to better address the cold weather shutdown issues, and 2) if one watch is preferable over the other. It makes sense to me that the 935 would be less susceptible to shutdown due to having a bigger battery, but I'm more of a running purist and would normally tend to prefer the 645 if temperature wasn't an issue. Thoughts?
It’s the battery technology that causes this, not the electronics. Always charge your watch to 100% before going out and it’ll improve the time until it dies. I suspect the 645 and 935 use the same battery technology so you are right, the larger battery of the 935 will mean it’s better in extreme cold.
I went for a run in 15F weather with about 75% battery charge and it shut off less than one hour into my run--only to restart and say that it still had 54% battery charge after it warmed back up
There is a very small possibility that this is a mechanical issue. If parts in the watch have a different thermal expansion coefficient then extreme temperatures (which 15F is) could result in something disconnecting.
I would suggest you monitor the battery percentage during your next run to see if it decreases from the start value to near zero before it shuts down (this would indicate it is due to the battery not liking the cold) or whether it decreases to some percentage (like 54 you mentioned before) and shuts down abruptly (this would indicate there might be a mechanical issue).
I am not sure the 630 has battery percentage as a standard data field. If not you could use my battery monitor CIQ data field which writes the battery percentage to the FIT file so you can have a look at it afterwards:
I have been observing a similar issue with my various Garmin watches, including Forerunner 305, Fenix 2 and now Fenix 3: when cross country skiing, running or hiking in low temps, I observe that the GPS occasionally loses signal. The watch keeps running and eventually it locks onto the satellites again. While I cannot say with absolute certainty that this is cold related, I am quite confident that it is, since it only occurs in very cold temps and when my watch is exposed. I can prevent it from happening by wearing it next to my skin and having it covered up. This would not be battery or mechanical related but rather an electronics issue. It seems that I am still within in the operating specs for my F3, which gives -20 C (-4 F) as the minimum operating temp. Here is an example of a GPS track from a workout that went rogue during a cold weather workout: https://connect.garmin.com/modern/activity/2408884414; I have had a handful of similar incidents for my F3 this winter.
The only complaint I've had with my 630 since I bought it when it debuted is that in cold temps the watch will shut off unexpectedly.
i have the same problem with my Forerunner 235, but after a while i noticed that it only occurs (even before showing the "battery low" - alert) when the watch takes an "autolap" AND vibration is turned on. As soon as vibration is turned off the watch works fine until the battery is really low . Interestingly i never had this problem on my old Forerunner 620, so i doubt that it's caused by battery technology . Hopefully Garmin solved this issue on the Forerunner 645
after a while i noticed that it only occurs (even before showing the "battery low" - alert) when the watch takes an "autolap" AND vibration is turned on
Interesting point. I typically notice the same thing, but had always assumed that the cold causes the watch to perceive that the battery is lower than it actually is, and then that the autolap/alert/whatever was sort of the "tipping point" that made the watch give up and shut down. I'll try turning off the vibration and see if it helps. Thanks!
Interesting point. I typically notice the same thing, but had always assumed that the cold causes the watch to perceive that the battery is lower than it actually is...
That's surely correct, and i noticed that the battery percentage increases ~5-10% when the watch warmed up after returning from a run in cold conditions, but these 5-10% don't explain why the watch suddenly shuts down at e.g. 40% or 50% even without sending the "battely low" - warning before.
It happened to me as well with a 920xt in good shape. I was expecting much from this watch, but the disappointment was therefore greater, when after only 3km the watch suddenly shut off, even if it supposed to last for 3-4 workouts more. I was using an older HR strap, and thought it was because of that too. Now I understand why some serious folks still use the (subjectively said) cumbersome POLAR (v800), even if the vast majority goes for Garmin..
