You'll need to keep an eye on two batteries; the larger, rechargable battery attached to the top of the dropper and a small, coin/watch-style (CR2032) battery in the lever.
The following details when and how I change the batteries, but it is nice that worst case - if a battery dies, you simply won't be able to use your dropper for that ride, which usually won't ruin the ride. I make sure to quickly test most aspects of my bike in the parking lot/trailhead before pedaling away, so I can catch any issues. I keep a spare seatpost and lever battery in my mountain bike bag, so I can swap them out before I begin riding if needed.
Charge the Dropper Battery
I tend to charge the battery before a big ride/trip or whenever I notice the LED to be red (I don't typically wait for flashing red as I'd charging the battery is free and easy. I also purchased and keep a spare in my cycling bag just in case
To charge the dropper battery:
- Remove the battery from the seatpost by flipping down the plastic clip and gently pulling the battery out.
- Place the battery in the small charger that came with the seatpost. It will only fit in one direction, so ensure it gently snaps into place and the LED charging light turns on.
- Allow battery to charge until the LED charging light turns green.
- Depending on the battery's remaining charge, it should take a few hours to fully replenish. The LED on the charger will show green when the battery is charged and ready to use.
- Remove the battery from the charger, place it back on the seatpost ensuring the retention clip pops into place.
Replace the Lever Battery
I'll haven't needed to replace the lever battery yet - it lasts a long time. But, I plan to do so around when the LED turns red (I check it every now and then when I remember). I also keep a few spare coin-style battery replacements in my mountain bike gear bag, so I have one handy if I don't keep as close an eye on it as I should and it dies unexpectedly.
If the battery does die on a ride, you can use the button at the top of the seatpost to change the seat height. Press/release the button, use your hand/weight to change the seat to the desired level and then press/release the button again (don't let go of the seat/height until pressing it the second time).
To replace the lever battery:
- Using a coin, remove the battery cover by turning it counter-clockwise (if the battery cover is not easily accessible, remove the lever from the handlebars first).
- Remove the existing battery and replace it with a new CR2032 coin-style battery.
- Place the cover back onto the lever and tighten it using a coin and turning it clockwise.
Battery Length of Use
When fully charged or new, the batteries will last approximately:
- Lever: 2 years of riding
- Dropper: 60 hours of riding
Whenever you press the lever's trigger to raise/lower the seatpost LEDs blink to indicate the battery level. One is on the bottom of the lever and another near the battery at the top of the seatpost.
You can also press the small AXS button at the top of the seatpost or on the bottom of the lever to make the LED display the battery charge level.
Lastly, you can view the dropper's and lever's remaining battery level via the SRAM AXS phone app. Pair your phone and dropper. Ensure the dropper and lever are awake by pressing the lever's trigger and its charge will display in the app.
If either battery becomes emptied, the dropper will no longer operate until the battery is charged/replaced.
|Green||15-60 hours left||6-26 months left|
|Red||6-15 hours left||1-6 months left|
|Flashing Red||less than 6 hours left||Less than 1 month left|
 I'll quickly test the dropper functionality, shift through a few gears to make sure my derailleur is working well, and I'll quickly run my eyes over some key bolts and give my headset a tug to make sure nothing is loose.
 All of SRAM's wireless components - their droppers and wireless shifting setups - use the same battery, which makes keeping a single spare handy in your car bag (or even in my riding pack on longer days) worth it.