I bought a Bose S1 Pro about four weeks ago. Now I am impressed, it's expensive but very small and unfeasibly loud. I'm finding the sound on Bluetooth playback a bit hyped in the bass but probably mostly down to the media (will try with a wire/CD player at some point), As a PA with acoustic guitar and/or mic it's pretty good and is pretty much the only thing that does what it does on battery power (discounting the Boss Street Cube EX which doesn't sound anywhere near as good and the Boss AC33 which doesn't go anywhere near loud enough on battery power).
Which brings me to the problem....... When fully charged it will run for several hours on battery power so all good, but, I left it in the car for a few days while on hols and took it out for a rehearsal the day before the gig and it was flat. It had been fully charged when I put it in the car and, I confirmed, had not been accidentally switched on. I subsequently tested it by fully charging and leaving it for a few days in a 'safe place' where there was no risk of it being switched on by mistake. Sure enough it was nearly flat when I switched it on and a further check showed the battery was losing roughly 5% of it's charge a day even when switched off.
This is pretty disappointing as the main reason for buying it was for it's battery powered capabilities and I need to be able to rely on it being ready to go without me having to remember to charge it the day before a gig. I have an AER Compact 60 and three TC VoiceSolo's that do the same job very effectively but don't have the convenience of the built in battery, much of what I'll use the S1 for will be spontaneous sessions and open mics or WHY so the battery option is fundamental to it's usefulness.
A Quick Google reveals that the problem is known and not uncommon, Bose posted the following on their user forum in April this year
If your S1 Pro battery is draining when the system is not in use and not connected to AC power, please continue to be patient while Bose implements a sustainable fix that can be carried out in all locations. In the meantime, please charge up the unit before each use.
Please note: This issue does not affect the battery life while you are using your system. The battery drain only happens when the S1 Pro system is off and not connected to AC power.
There is no need to contact Bose Support about the issue. When there is a resolution, we will announce it here in the community."
As of today there have been no further announcements.
I have arranged to exchange my ex display S1 for a box fresh one and will see if that has the same issue, if it does I will have to reconsider the position.