Right, let’s sort this out properly. Nothing worse than being halfway through a lovely ride around Rutland and your Di2 decides to throw a wobbly because the battery’s gone flat. I’ve been caught out before, and trust me, it’s not fun being stuck in one gear on those hills near Empingham!
Checking Your Main Di2 Battery
The quickest way to check your main battery is right there on your rear derailleur. Here’s what you need to do:
Press the function button on your rear derailleur for less than half a second. You’ll see an LED light up with different colours telling you exactly where you stand:
- Solid green: 51% to 100% – you’re golden
- Flashing green: 26% to 50% – still plenty left
- Red: 1% to 25% – time to get that charger out
- No LED: Completely dead – you’re in trouble
Important tip: Don’t hold that button too long! If you press it for more than 0.5 seconds, it’ll flash blue and go into Bluetooth pairing mode. We don’t want that right now.
Checking Your Shifter Batteries (Wireless Di2)
Your wireless shifters have their own coin batteries (CR1632s), and they need checking too. Press and hold both shifter buttons at the same time for about half a second. Each shifter has its own LED that’ll tell you:
- Green: 11% to 100% battery – all good
- Red: 1% to 10% – you’ve got about a month before it dies
- No LED: Dead as a dodo.
Don’t forget to check both shifters – left and right each have their own batteries. The 105 Di2 actually has two CR1632 batteries per shifter, whilst Dura-Ace and Ultegra have one each.
Using Your Garmin or Wahoo
If you’re running a Garmin Edge (like most of us in the club), you can set up a Di2 data field that shows your battery levels right on screen. Dead handy when you’re out on a long ride and want to keep an eye on things without stopping.
Using the E-Tube App
Shimano’s E-Tube Cyclist app is brilliant for this too. Connect via Bluetooth (press and hold that rear derailleur button for 0.5-2 seconds until it flashes blue), and you’ll see all your battery levels in one place. The app will even ask you to press buttons on each shifter to wake them up and get current readings.
My Experience with Battery Life
I’ve found Shimano’s pretty conservative with their estimates. They reckon about 1,000km per charge for the main battery, but I regularly get closer to 1,500km. The shifter batteries? Well, those CR1632s last ages – we’re talking a couple of years of regular riding.
When Things Go Wrong
If your main battery gets really low, the system will stop you using the front derailleur first. Once it’s completely flat, you’ll be stuck in whatever gear you’re in – not ideal if you’re facing the climb up to Colsterworth!
Quick charging tip: The main battery takes about an hour to fully charge. Just plug the charging cable into the port at the back of your rear derailleur and you’re sorted.
Local Battery Hunt
Speaking of those shifter batteries – good luck finding CR1632s in Stamford! I’ve been round every shop in town, and they’re rarer than hen’s teeth. I ended up ordering a bulk pack online after being caught short before a club ride. If you’re desperate, shout up in our WhatsApp group – I’ve always got spares.
The key thing is to check your batteries regularly, especially before longer rides. There’s nothing worse than having your Di2 pack up when you’re miles from anywhere. Check them, charge them, and keep riding!
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