After each shift, an LED light on each component turns on.
The indicator lights for battery life are as follows:
Rear derailleurs:
Green LED: >25% charge, 15-60 hours of ride time remaining
Red LED: <25% charge, 5-15 hours of ride time remaining
Flashing red LED: <15% charge, less than 5 hours of ride time remaining
Front derailleur:
Green LED: >25% charge, 22-90 hours of ride time remaining
Red LED: <25% charge, 9-22 hours of ride time remaining
Flashing red LED: <15% charge, less than 9 hours of ride time remaining
Shifters:
Green LED: >25% charge, 6-24 months
Red LED: <25% charge, 1-6 months
Flashing red LED: <15% charge, less than one month
See the SRAM RED eTap System Overview video for a visual of the indicator LEDs.
Sensors in each component ensure that they go into sleep mode automatically when you aren’t riding to limit battery trickle down.
Battery status is also available on many cycling head units and on the AXS Mobile App. Typical run times on a single charge are 60 riding hours. It takes one hour to fully charge a battery.