i use this, works like you want it to.. starts at a given time, stops after given time.
you have to program it. I always arrive at the office around 9:30 - 9:45 am so I have it set to start charging at 11:30am, I know it takes 4 hours to 4.5 hours to charge my bike, so I have it shut off at 4:00pm. 8 months no issues.
use the same unit at home, starts at 10pm at night and shuts off at 2:30am. every once in a while I note the battery is not at 100% but close enough. 100% on my bike is 54.5volts occasionally I see it at 52.5 - 52.9 at startup in the morning. just means it needed another 30 minutes and my timer cut off too soon. this usually happens when I take an alternate route home or to the office due to traffic or construction adding another mile or 2 to my normal commute.
like you I commute to/from work 4-5 days a week on my bike.