No. You can charge your BESV battery at anytime. Your BESV battery is a lithium-ion battery cell, which has no memory effect.
However, it is recommend that you keep your BESV battery as fully charged as possible at all times, in order to extend its lifespan.
Generally speaking, the charging efficiency of a battery diminishes in conjunction with the battery’s lifespan. For example, after the battery has been charged more than 300 times, it can only be charged up to 80 percent. After 500 charges, it can only be charged up to 75 percent. And after 1,000 charges, it can only be charged up to 60 percent.