The best way to maintain your Lithium Battery is to:

  1. Charge it frequently without letting it drop below 20-30% charge.
  2. Operate it between 30%-90% charge without  discharging it fully. This will increase the charge cycles of the battery many times.
  3. Operate and store it in a cool environment as much as possible. Performance and capacity decreases in high temperatures.
  4. Store the battery in a partially charged state of 40-50%.
  5. Recondition it by using the bike normally till power drops and give it a full charge.
This implies that fully charging your battery isn't good.  That isn't the case, but you don't want it to be fully charged at all times.  The main point is to vary the level of charge.  

Regarding storage, it is always better to store the battery in a fully charged state than a fully discharged state.  In fact, storing a discharged battery shortens its life dramatically.

You shouldn't CHARGE the battery when below freezing, and whenever possible, store it in a temperature controlled environment.

Temperature extremes can affect your battery. Please keep it within the following
temperature ranges, as suggested by the battery manufacturer.
Charging: 32 degrees to 113 degrees F (0 degrees – 45 degrees C)
Discharging and Storage: -4 degrees to 140 degrees F (-20 degrees to 60 degrees C)