I have had a 2012, 2013, 2014, 2016 and 2018. The 2012 was lower voltage, so not comparable here.
The 2013 FX I have was an orphan year and is the only FX in the 96 volt category That is different.
Also, the FX seems to have a lower output onboard charger so that will also be different than your DS.
Until 2014 or so, Zero said that if your butt wasn't on the seat, the plug should be in the wall. Battery
people will disagree. Cell Balance on my 2013 is all over the place. Getting down to where it should be
when at or near full charge. My 2014 and 2016 were always charged to around 60~80 percent for
everyday use. Every few weeks, I would charge to 100% overnight before a ride to balance the cells.
No issues on my 2014 or 2016. I recently acquired a 2018 FXS which seems to be between 1 and 3
for balance when full or near full, but goes out to around 20 as charge gets lower. 2018 Manual
says that if cells are way out of balance then leave bike plugged in for as long as 72 hours to balance.
Not a lot of luck with that yet. My 2013 FX gives similar information to what all my other bikes do
so that should not be an issue. Bikes are never charged or stored in direct sunlight or extreme cold.
The only thing that I have noticed with the key on or off is that if bike has reached full charge and
been sitting a bit, key on will reengage the charger and bump the charge up a bit. It may make a difference
in how it reads, but, doesn't really add any real life range. The App " should " read all the way to full and
a little past where the charge light on the dash shuts off. The app " should " show it still charging at that point.
I live in Vegas, so Hot should be an issue, but, hasn't seemed to be.
Whenever possible, if using the onboard charger, I use a 1772 adaptor and 240 Volts. If using 120 volts,
I try to use a QuiQ charger.
All bikes prior to SR/F and SR/S should be similar information. Not sure about FXE.
If anyone disagrees, please let me know. We can never have enough education.
Hope this helps.