The bike gives more power when the battery is full in my experience.
Or in other words, the bike performs worse when the battery is getting low. I have more problems getting the speed over 40 km/u when the battery is at 20% to 10%. The last few percent I only barely get over 30 km/u and then it dropped out at 0%
.
So big reason : the ride is more fun with a fuller battery
.
And I had one trip where I used 40% (so I parked it at 60% and turned it off), but I didn't manage to do the same trip in reverse. I had an empty battery with 3 km left to go.
So, 30km takes 40% one day, but takes more than 60% the other day. I don't dare to _not_ charge at 50% anymore
. Or if I really have to, I go into powersaving more way earlier
.
So big reason #2, I wouldn't count on it to make the 2nd trip if you have 53% left.
And, like the others replied, it's believed to be better for your battery. Yes, it will count as a charge cycle, but you will manage way more cycles before your battery degrades to like (for example) 80%.
To be clear, 'it is believed'.. I think we don't know for sure (yet). I believe there are a couple of people emptying their battery almost every day and having fine batteries after 3 to 4 years.
I do advice to not worry to much about it.
I DO recommend to charge between trips, just for your riding pleasure and not taking the risk to have an empty battery on trip #2.