External Battery Pack and the internal battery

1862802 15 days ago

I just got the External Battery Pack for my new Edge 850, since I got a good deal over Black Friday. It seems to work fine at first unboxing, but I noticed that there are four screws on the underside of the case. Now I realize that this does not technically have a user-replaceable battery, but I was just wondering if anyone has tried disassembling one of these units. If so, is it a battery that could be replaced (voiding the warranty, of course)? If need be, down the line, as batteries always eventually go bad. Just curious if anybody has had a look inside.

0 1862802 14 days ago

Incidentally, I'm running a little test right now to see how long the external battery pack will be able to keep the 850 going. It's probably not very representative of real life, since the 850 isn't doing anything but sitting on my desk, but it has auto-off disabled so the screen is on all the time, on auto brightness. So far it's been 24 hours and the battery pack says it still has three lights (out of four). The 850 is of course still at 100% (since the battery pack is used first). This is pretty nice so far, especially since people say that it's the new screen that causes at least some of the additional drain on the battery. So I'm quite encouraged, cautiously, though I do realize that it would probably drain faster out on the road (I don't have any external sensors, just the GPS, but presumably it would use more power in sunshine, to make the screen brighter).

Would the 850 use up battery more quickly if it was on the bike rather than on my desk, all other things being equal? I mean, it already has the GPS "on", the screen is already on, so it seems to me the only extra thing would be turning the screen brighter in sunshine. But is there anything else going on inside when it's recording a ride, that makes the battery drain more quickly? Maybe the CPU would be doing a bit more work, I could see that. Anyway this is just an initial test to set a baseline, then I'll do some riding to see how different that is.

Update: At 36 hours, 2 bars left on external battery pack, 850 at 100%

Question: The system is designed to run down the external battery pack first, before switching to the 850 internal battery. So presumably at some point it decides when the level on the external battery is low enough. I know it's bad to run lithium batteries to zero, so does the external battery pack have firmware that is able to calibrate when the switchover happens, so that it doesn't damage the external battery? You'd hope do, in fact it must do, because when you are on rides, of course this will happen all the time. So I'm assuming I don't have to be careful about taking the external battery off the mount, since it will know to switch before "too drained" damage occurs. Let's hope so... it would be nice if the manual talked about this, because all it says is that the external battery pack with flash with one light when it is at 5% capacity. However it doesn't say anything about what to do then. Do you just leave it, and it knows to stop providing the Edge with power, in order to preserve itself? Or will it just mindlessly keep giving, to the point of damage? I wish the manual was more clear on what it does at that point... or what I'm supposed to do. Remove it from the mount to protect it? Or just leave it on, knowing it will be ok? How watchful do I need to be here? Anybody at Garmin want to educate me on this, I'm all ears.

Answering my own question, via Google AI, apparently the external battery pack will automatically turn itself off when it is depleted, hopefully not damaging the battery inside. According to two cited forum discussions:

Edge 1030 and External Battery Pack (aka "Power Pack") -- Battery Life Test.

RE: Garmin Charge Power Pack Questions

0 1862802 13 days ago in reply to 1862802

Update 2: 48 hours in, still on external battery, one bar left. 850 still 100%.

Update 3: The external battery pack started flashing and then cut out at around 52 hours. Now the 850 is on internal power only, I'll see how long that lasts. I'll just keep counting from the start of the whole test, so I can get an idea of the total runtime using both.

Update 4: At 60 hours (8 hours for the 850 by itself) it is at 77%. The external battery pack recharged from fully empty to full in a little over two hours, using the charger that came with it.

Update 5: I'm calling it at about 73 hours, the 850 is down to 23% and I don't want to let it get too low, so I'm going to say something like 75 hours as an estimate for the total (with the external battery pack giving me over 50 hours, and then the 850 lasting about 23 hours by itself). This is better than I expected for the 850, to be honest, and much better than I expected for the external battery pack. I know it'll probably be less on the road, for whatever reason (increased CPU usage, more screen brightness in the sun etc) but still this is pretty ok by me - 75 hours would be about 9 days if I was using it 8 hours a day on a bike tour (which is my thing). That's very respectable in my book, and I could get even more "off the grid" if I brought along my Anker Powercore+ 26800 mAh powerbank. I like the external battery pack, despite its somewhat outrageous price per mAh, I feel like it's worthwhile to have an integrated solution that doesn't require any dangling cables. And I have to admit I'm a little bit OCD so having the "official" battery pack just satisfies that side of me, and the fact that it seemed to perform very well indeed is icing on the cake. Very happy. I got a good price from Performance Bicycle, fwiw (and no I am not affiliated with anyone, I paid for all of it out of my own pocket and this is just in case anybody else might find it useful).