Instinct 2 solar charging - how many % battery level increase?

I never observed any increase in battery level, but it does expand your battery life.

Sometimes when I'm in the sun and don't run any activity I see the % go up.

If you want to see more details and notice smaller increments try to use my BatteryGuesstimate app: https://apps.garmin.com/en-US/apps/572b8232-7fb6-4e4f-a938-2395d0df3c7c

It gives you more details. But it also looks like if the battery is charged with solar it loses that charge quicker than if it's charged by cable. There is somewhere a topic about that in the forum, but I cannot find it anymore.

There are other strange things with the battery e.g. after plugging out the charging cable  the battery charger jumps up a couple % https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/instinct-2-series/321909/battery-jumps-8-10-after-charging-is-stopped

It's all a bit weird, but still charging with solar seems to work, if you are patient

Could you please help try to observe it?

The reason I asked because I did the following test.

(At that time there was no battery percentage when we push the down button, so before the test I connect the watch to the charger to find out how many percentage it has. And after the test I did it again to find out how many percentage it has now.)

I put the watch in a place where it gets plenty of sunlight (I live in Bangkok, Thailand), then let it lie there for more than four hours and I got the battery increase 4% from 19 to 23! (Solar intensity widget shows a lot of 100% though.)

So 1 hour solar charge got about 1% only?!?

How come?? That's why I append it here to find what other users' experiences for solar charge are. (I think my watch solar charge functionality may be broken..)

Note:

1. When I charge the watch via the adapter, it took about 2 hours so 1 hour electric charge, I can get about 50% battery level increase...

2. I learned from here that what I did above may not be correct because the watch may be too hot and stop charging... So I will test this again by putting the watch in a water container to help with the cooling.

I have installed your widget and tested today by putting the watch in a container filled with water and left it on the place where the sunlight came through.

The test was during 1050-1450 today. Now the time is 1505. (I also got a lot of 100% solar intensity on this test too.)

Battery level on the starting test is 20%, at the end of the test is 24%.

Here's what your widget showed: (detail view)

Time: Battery change:
15 min +0:00%
30 min +0:29%
45 min +0:58%
60 min +0:58%
75 min +0.87%
90 min +1:16%
105 min +1:45%
120 min +1:74%
3 hours +2:03%
4 hours +4:64%
5 hours +4:64%
6 hours +4:64%
9 hours +3.77%
12 hours +2.90%
15 hours +2:03%
18 hours +0:29%
21 hours -0.66%
24 hours -1.77%
2 days -17.01%
3 days +0:00% ....I think the data is 0 because I haven't installed the widget yet.

(Please advise if I misinterpreted the data) so it looks like 4 hours charge gave me 4.64%?

Is this normal?

Thank you very much.

Yes, the system reported 4.64% higher battery level between when you looked an 4h earlier

From your experiences, is that in an expected range of values?

Thank you very much.

I've just spend my lunch break outside in the sun (~32min 100% solar) and here are the values the widget reports:
15min: +0.44%
30min: +0.87%

Solar intensity:

Hi,

! Operating and storage temperature range From -20º to 60ºC

1. The outdoor temperature here never exceeds 45C.

! Also: I would be more worried about leaving the watch in the full sun for 4 hours:

2. Me too.

However, I read somewhere in Garmin document that the watch will automatically stop charging if the temperature is too high to protect itself! (That's why I conducted the test, otherwise I would not dare...)

In my testing, my watch was indoor where it can receive plenty of sunlight, so it's not really outdoor in the full sun. (But the solar intensity was nearly 100%.)

(For recent tests, I started to put the watch in the water container to help cool it down, like one poster here recommended.)

! NOTE: Solar charging is designed to extend your time between charges. It is not designed to be used as the primary charging source or to achieve indefinite power.

3. I am aware of that.

In fact, there is an additional document in Thai coming with the product saying that "Do not charge it with the fast charging adapter" and "The best way to charge it is from the PC USB port".

So I always charge it from my notebook.

4. I got the watch in October and in November I was on vacation in KL for 15 days and I did not bring my notebook with me.

Before I leave, the battery said that it can be used for 20 something days, so I think it was more than enough and thus I did not bring the charging cable.

However, the estimation didn't include any activities (I learned it here), thus, after some time, I had a low batt while I was in KL.

So I had no choice but to use solar charge by putting the watch in the sun, hoping that it can help increase the battery life.

After 4 hours, the battery level was still low batt and after a day it was completely out of power!

I was very surprised that it did not seem to increase the battery much (at that time, I did not know how many percent it increased).

When I am back to Thailand, I did some more tests and found out that 4-hour of solar charging only gave me 4% battery increase!

(So one hour of solar charge gave me 1%, while one hour of electric charge gave me 50%! I am aware that solar charge will be lower but I never expected it to be such a huge difference!!)

! So I think your values are more than expected.

5. I would not conclude that yet. So far we only have 2 testcases:

Mine 0.29% per 15 min & Yeti 0.44% per 15 min.

Considering only these available data, mine is below average.

6. I would appreciate if you can help test like Yeti did, so that we have more information to draw more accurate conclusion.

7. By copy to other Garmin users who view this post, I would greatly appreciate if you can help test and post your results here.

(It looks like the increase is linear with time, so a 30-minute wearing in the sun like Yeti did is enough.

Please test while the battery level is low (since the watch may not solar charge if battery is already high enough)).

Note: for those who do not want to be in the sun for 30 minutes (like me), you can put the watch in a container filled with water up to the clock face. Then put it where there are plenty of sunlight.

Thank you very much for your kind help.

1. In your case, it looks like we got 0.44% increase per 15 min consistently, while in mine, it was about 0.29% per 15 min. (I will test again later to see that the 0.29% data can be consistently achieved.)

2. A fully charged battery are shown to be able to use for 30 days (without SpO2 usage). But with some activity recording (less than 1 hour per day), I found that it lasted about 15 days.

So 1 day usage of battery is about 100/15 = 7%.

3. Suppose that we are in the sun for 4 hours a day, in your case, we get 0.44*4*4 =7.04%, which is enough for one day usage.

However, in my case, we got 0.29*4*4 = 4.64% for 4 hours. To get 7%, we have to be at least 6 hours in the sun!

4. I wonder what other users' experiences are...

Thank you very much for your kind help.