Battery life review

[Triletics]

Last week, I looked at how much juice I could squeeze out of the Charge 6. Overall, it's good, and pretty much standard for Fitbit devices.

My setup was:

- SpO2 enabled
- Always-On display during activities (except swimming)
- GPS in 'Phone' mode
- Brightness: dim
- Autowake
- Only Swim is set to be autodetected

Activities:

Total: 8:59:28 (not tracking walking, I don't track walking)
Running: 5:02:03 ('Phone' GPS)
Swimming: 3:15:05
Others (strength, recovery):  0:42:20

All runs are tracked with GPS in 'Phone' mode. The reason why I used 'Phone' mode is very simple - no other mode ever worked for me. I would like to see how long the battery can last when using built-in GPS but it's not possible when GPS doesn't work. It does connect, but after a few minutes, it disconnects and never reconnects again. It's a dead feature. Similarly, the 'Dynamic' mode. Only 'Phone' mode did work for me.

To go from 100% to 8% it took the battery 6 days and 17 hours. Since I was testing it against Fenix 7 and both devices were showing very similar power usage, the Fenix 7 prediciton of extra 13 hours (to go to 0%) is probably also valid for Charge 6.

It is a decent battery life. Nothing impressive knowing what's out there and that some devices last weeks on a single charge. One disappointment I have here is that using 'Phone' GPS mode consumes more power than I expected. In fact, by the percentage (relative consumption) it consumes more power than Fenix 7 with all modes enabled (GPS, GLONASS, GALILEO). Also, while using 'Phone' mode and making sure the Fitbit app doesn't go into the power saving mode my phone started moaning about high battery usage by the Fitbit app.

The good thing is that battery life is pretty much what's advertised. I wish I could test it with the built-in GPS but that isn't possible because built-in GPS doesn't work at all. Testing the Fitbit tracker against Garmin 7 (SpO2, AoD 24/7, GPS, stronger backlight after sunset) it comes up pretty much the same (which is better than Sense 2 was). From past week, I don't see much difference with and without SpO2 on Charge 6 (that makes a huge on Fenix 7, turning off SpO2 can add 2 more days). I noticed that SpO2 is almost "free" on Sense 2 and it seems like that trend continues on Charge 6 (which I like as there is not much benefit turning SpO2 off for me if it doesn't prolong the battery life significantly).

Overall, battery life test passed. It is what it says and it may probably get a little longer for people who turn GPS entirely off and stop using SpO2. Considering that it and the prediction given by Fenix 7, it may last even 8 days on a single charge.

I have seen some posts here about very short battery life. In such a case, I recommend contacting customer support. If you're not using built-in GPS a lot and Charge 6 batter life falls under 2-3 days then no change in any settings (there are not many of those anyway) will make a difference.

[EmFit13]

That is what my Charge 5 was but this Charge 6 lasts 4 days have it on dim, manual wake.  What else drives battery down?

[SpearC]

My Fitbit charge 6 dies when the charge rate gets to 36% ( less than 3 days) . I have to put my dead charge 6 ( black screen) on the charger and hit the charge reset button 3 times, wait for the Fitbit logo and let it sit one minute before I can see the charge %… always starts at 36% .

[EmFit13]

I’m continuing to monitor closely. Charged Sunday mid day. At 54% as of 8am a little less than 3 days. That would be on track for 5-6 days but maybe the end accelerates.

Sent from my iPhone

[Triletics]

Currently, with the new charge cycle, the battery dropped to 71% within 2d18h. Only on Monday, I went for a run but because I feel kind of under the weather I stayed lot less active. SpO2 is on, screen dim. Very low usage (basically, tracker is just on my wrist, not using Exercise app or anything else) would be around 9 days. Interesting that observing the same usage pattern, my Fenix 7 maintained 78% battery and still predicts 9 more days on single charge (which I have validated before so no reason to doubt it). This is mostly due to battery capacity and different display technology (Fenix 7 can be always-on with almost no cost). Of course, I will try to get more active within this charging cycle but it looks like Charge 6 in my case lives what's been advertised.

If you have any problems with battery life, could you add more details about your own usage pattern? For example, what did you track during that cycle, what activities, GPS on/off/which mode, SpO2, whether you check ECG, setting for always-on display etc. all of it contributes. Like I said, I don't track walking which probably is a main activity Charge 6 users track automatically so for me it may be an energy saver.

[EmFit13]

Have dim and manual awake on. Track sleep, spO2, body temp, resting heart rate. Only have used EKG once or twice. Not in this cycle. GPS off. Mindful stress level on. Detects exercise. Walk Elliptical etc. think that is the majority of what I use.

Let me know if any of those should be turned off.
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[Triletics]

@EmFit13 this looks pretty standard to me what trackers comes enabled with out of the box. I use wrist gesture to wake screen up. That should deliver decent battery life so manual wake adds to power saving. From your first post, 4 days (can you be more specific on start and end battery percentage, is it 100% until watch died?) is definitely short battery life for this kind of use-case. 6 days would be probably ok(?). Except SpO2 and AoD there are no other things that can consume excess power. Even GPS is enabled only when you decide so, it's not a passive feature. With GPS (phone mode), I got nearly 7 days. The only difference I see is that I don't autodetect anything else but swimming. Walking is irrelevant to me, I track running using Exercise app (with GPS). The only reason why I detect Swimming is that it doesn't turn of HR sensor and it collects HR data when auto-detected (which also, in theory, consumes more power than manually tracked swimming as the HR sensor is enabled). I will give it a go and see whether tracking regular walks through auto-detection has any impact on battery life but that I will do with next charging cycle.

[EmFit13]

Thanks for the feedback. I will update on this charging cycle.

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[Triletics]

The second battery cycle:

100% to 10% - 7 days 14 hours
Less activity this time due to illness and a busy week:

Running - 3:01:48 (GPS 'Phone' mode, AoD during activity)
Strength - 0:48:45
Swim - 1:32:36 (2 swims, auto-detected)

Total activity time: 5:22:21

SpO2 enabled, nothing changed in the settings. Screen dim and auto-wake.

It's quite a decent battery life. The major difference is that I don't track walking which would force activity tracking more often (and may consume more battery). With the next charging cycle, I will enable automatic detection of walking and see whether it will shorten battery life. 90% within 7+ days is an excellent result (although, not as good as my Garmin Fenix 7, down by 81% from 100% within the same time, using built-in GPS, AoD 24/7).

[EmFit13]

I recharged last Thurs after 4 days and it had gone from 100 down to 29.  I knew opportunity to charge on Friday was limited.  It is essentially the same today after 4 days.  I’m going to see what it goes down to in the next 24 hours but based on last 4 days 15%-17% per day.

[Triletics]

Update for yesterday. I decided to see what would happen if I didn't have a charger but still wanted to go for a run. Whether Charge 6 would last long enough for me:

100% to 4% - 8 days 2 hours

Running - 4:09:17 (GPS 'Phone' mode, AoD during activity, 4 runs, 48.46km total)
Strength - 0:48:45
Swim - 1:32:36 (2 swims, auto-detected)

Total activity time: 6:29:50

This is an excellent battery life. I managed to go for an extra run and the tracker still lasted until the end of my work. I plugged it charging when I got home.

@EmFit13 I noticed that the battery percentage on the tracker isn't decreasing in the expected linear manner. When I started my run yesterday the battery percentage was 10% and after I finished it still was 10% (usually, it goes 3 to 4% down during 1hr run). Then, after about 30min it dropped suddenly to 6%. So it's hard to take an estimate but this is behaviour I observe in all the wearables. When the battery drops to a certain level the level indicator is less predictable.

I'm going to turn on auto-detecting the activity for this charging cycle. I'm curious whether that enables some heavy algorithms that may deplete the battery quicker which is what some users observe. I believe the fact that I don't track walking and don't auto-detect it may have something to do with longer battery life.

[EmFit13]

At 20% this morning and noon on Thursday was when I charged it so 5 days on average to charge.
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