Hum, I guess this makes me think more, if you set it to Discharge in 2 days, so after say 48 hrs, with the battery at 100% how many hours or days would it take to complete the discharge?
The 2 days you defined is the delay before the auto-discharge starts.
Below are two examples roughly explaining how auto-discharge works:
Ex. A: 2 days delay:
If you fully-charged the battery to 100% on Sunday (July 31), the auto-discharge would only start on Tuesday (August 2) and would take around until Thursday (August 4) before the battery gets down to 60-ish%.
Ex. B: 10 days delay:
If you fully-charged the battery to 100% on Sunday (July 31), the auto-discharge would only start on Wednesday (August 10) and will be down to 60-ish% by Friday (August 12).
It is important that you don't disturb the battery or the delay will reset. If you even press on the button on the battery to check the level, that will cause the delay to reset. Powering it up will also cause it to reset.
To illustrate this, consider a variation of Example B: If you fully-charged the battery to 100% on Sunday (July 31), but then on Monday (the next day), you pressed the power button to check on the level, etc., then the auto-discharge would only start on Thursday (August 11) and will be down to 60-ish% by Saturday (August 13).