I had a retrofitted e-bike running a [Leed e-bike kit][1] for 4 years. After 800 charge cycles the battery was toast. However this system is quite basic with both the battery management & charger.

I have replaced that bike with an e-bike running Shimano STEPS e8000. This has more sophisticated battery management (I believe it doesn't use the bottom 20% or top 20% of the battery to extend life) & a more advanced charger.

However I want to make sure I get as much out of the battery as possible. On most days I ride <10km which hardly uses any of the battery capacity.

I've come across two theories for improving battery longevity:

 1. Charge every day - that the depth of the charge effects battery health more than the frequency of the charge. So frequent shallow charges is best for the battery.
 2. Charge infrequently when the battery reaches a certain level (say 50%). So lowering the number of charge cycles is best for the battery.

I am really curious to know which of these approaches (or another approach) is the best to extend the life of the battery.

Thank you in advance.

  [1]: https://www.e-bikerig.com/