I have got 8278 miles (544 moving hours) on the 12-speed Dura-Ace shifters - set up wireless - that were installed in February 11 2022. And yet when I check the battery status - by pressing both shifter buttons simultaneously - the LED still shows green. According to BetterShifting.com, that’s between 11% - 100% battery. Has anyone actually gotten some kind of alert to replace the coin cell battery (CR1632) in the shifters? I am asking because recently, the left shifter has been taking longer to wake the front derailleur up and occasionally during a ride, it would take more than one press to shift the FD. Perhaps the battery indicator on the shifter is not reflecting the actual battery life? And perhaps this is the reason why Shimano still does not allow the wireless shifters to be updated wirelessly, because it does not have a clear idea on the battery life and does not want the shifters to be bricked in the middle of a firmware update?
I’ve found that Shimano’s Di2 system can tend to be a little “sluggish” when the battery is about to be depleted. I’ve never come across a situation that requires swapping out the batteries to be honest. I usually just swap them out every year or so (for bikes I own, and for clients that ride less regularly).
Maybe, just swap yours out and see if that solves the issue? Coin cells aren’t usually that expensive anyway…
Interesting - I’ve been thinking my shifting has been a tad sluggish of late but wasn’t sure if I was imagining it or not. I might try a battery swap.
If you have a multimeter, would be curious to know the battery voltage reading if you remove them
First, it was lighter tools, now it’s quicker shifting. I reckon someone’s just jumped onto the marginal gains train maybe? 
Just messing about…
I’ve received the alert for one shifter. I crashed that bike and destroyed that shifter after a week of it alerting every ride.
Haha - didn’t you see this?
I got the alert to replace the battery after 23,943 km.
Melbourne winters. Gotta love them, especially when wet… 
The battery from the left shifter measured 2.4 V.
A battery that I removed from my TyreWiz 2.0 that reported low battery measured 2.33 V.
My original 11 speed ETap shifters on my good roadie that I bought in December 2017 still have the original batteries in them and I just checked the LEDs are still green!
Strava says that bike’s only done 14,500kms because I keep it for good and usually ride my CX bike. That said, the bike lives in our unheated garage in Canberra, so it gets bloody cold.
I’ve been carrying spare batteries for the last year or so, ever since all my ride buddies were getting caught with flat shifter batteries in <2yr old bikes.
I can’t bring myself to simply replace the batteries just in case, because there’s no way a replacement will last as well as these have!
I replaced the batteries and the long delay in waking up the front derailleur is no more.
Pretty happy for you, and that that mystery was solved. Was going to go with just, “Yay!”, but character minimums and all that.
Looks like Shimano needs to update its battery light to warn before 11%. A 20% drop in voltage should qualify as low battery to me
I check the battery level in them with a dedicated page I’ve got set up on my wahoo roam head unit.
I am on GRX825 shifters and I have a very shitty battery problem. It’s usually the left shifter. I keep getting a problem where I get a critical battery warning on my Garmin and a red light on my shifter. First it happened at about 5k miles on the left shifter, I replaced the batteries. The next day, I started with a green light on the left shifter and then I had a critical battery warning at the end of a short ride. It happened a third time last Sunday. I removed the battery, measured 2.33v on each, then placed them back in the shifter and it’s worked fine on three rides since. I’m perplexed and very frustrated.
No experience with di2 but I replace my axs shifter batteries each spring. This is to some degree preventative maintenance but I will say cheapo 2032 do not last well at all. Recommend energizer or Duracell.
Update: I don’t think my issue with the left shifter is battery-related. E-tube app is not reporting low battery and in the E-tube app when checking for firmware update for the shifters, the left shifter always take significantly longer time to be recognized by the app after pressing and holding one of the buttons.
How long does it take for you to wake the Di2 system up after it has gone to sleep? When I press buttons on the left shifter after Di2 has gone to sleep, it takes 7 seconds before the front derailleur would respond. In comparison, the right shifter takes probably a couple of seconds to wake the system up.
That’s one way to take care of the alerts.