b'Twin Cargo Bike R500E Notice D'utilisation page 13

Recharging the Battery
Green LED when charging is complete.
Maintenance and lifetime (warranty conditions)
3 months
Zzz
z
The LED is red as charging starts.
5H
Do not store the discharged battery to prevent deep discharge that may cause malfunction.
Charge the battery fully at least once every 3 months.
When storing the bicycle for a prolonged period, put the battery in extended standby mode (see
details p. 14)
LED flashes red, charging problem,
contact the after-sales service.