This shouldn't happen as it's a lithium ion battery which shouldn't self discharge more than ~2-3% a month. Which suggests there's a drain on it somewhere.
Have you checked the connection? With the battery below the BB it's exposed to loads of crap and dirt and silt can get into the unit. I've noticed this before with mine.
Shimano Ultegra 6770 di2 Issues
19 Jun 2017 12:02 #10655
Any advice welcome.
I have shimano Ultegra 6770 di2 issues. After a full charge the battery discharges (when connected to bike) within 72-96 hours despite not being used. I have bought, charged and fitted a new battery and this does exactly the same.
As I am no bike expert I wondered if anyone knew what might be causing this.
Thanks for your help.