Gentlemen & Ladies,
I found this thread a few days ago and wish to add my 2 cents.
My S1 Pro (purchased in Mid-September) was used every few days during the first couple of months I owned it. Unaware of this issue, I did not pay any attention to this as a potential problem and my habit with most everything is that I "always" plug-up any battery-operated equipment to fully charge before each gig.
Since I have had no events after New Year's Eve and, now knowing about this potential issue, I was able to check to see if I have the problem/issue.
I had plugged the S1 Pro into an AC outlet to charge on NYE day and had it fully charged before my event that evening. After arriving at the venue, I found that the S1 Pro was not needed (I used my L1 Model II and my L1 Compact only). I left it in my vehicle and had a great event. I have not touched it since then (until a couple days ago).
Since my next event is January 19, I started planning which equipment will be required for that venue a couple days ago. Now aware of this issue, I turned on the unit on Friday and paired it with the Bose Connect App to find that it only had a 10% charge (even though it was not used since the afternoon of full charging on NYE). After a full charge on 12/31/18, I discovered only a 10% charge on 1/11/19.
Of course, this means that I am having this "issue" as well as the others who have posted here.
I will call Bose Support tomorrow and see what they suggest. In the meantime, I will plug it up and fully charge it before next Saturday's event as I am sure that I will need it. i would have done this anyway, but agree that this should not be necessary.
Thanks to all of you who so patiently share info like this with our fraternity of Bose users in this forum. Also, a big "thank you" to ST for his unwavering and prompt willingness to help us as our "first line of help" whenever needed. ST... you're a valuable resource for us and we appreciate all that you do to make life easier and better for us!
Happy New Year to all! I will report any/all info and updates I receive from Bose and wish you all your most successful year ever in 2019!