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The right tool for the job.

This is the one common item between all of Shimano's Di2 groups -- the Di2 SM-BTR1-67 Battery. Call it Ultegra, call it Dura-Ace, but we'll call it the one you'll need. It's a rechargeable lithium-ion battery that mounts on a bracket designed to work with bottle cage mounts. The mount stays on the bike at all times, though the battery can be removed for charging.

Everyone's first question is about battery life. Shimano sat back and watched Mavic on both its attempts at electronic shifting. Both their Zap and Mektronic groups were susceptible to surprise failure. In a nice gesture, Mavic designed the rear derailleur so that the rider could manually move the pulley cages to choose a gear to ride home in. And it happened all too often.

For the prospective Di2 buyer, know this: running out of juice is nearly impossible. Besides the long battery life and short charges, there is a service light integrated into a module that is part of the shift wire near where it exits the tape under the handlebar. Holding one of the shift paddles down for a few seconds will activate the indicator light. When the light is green, it is fully charged. At 50% charge, it will start flashing green. At 25% charge, it will turn solid red. It will flash red when the battery is critically low. One nice aspect to the electronics in the Ultegra Di2 kit is that the battery is in a sleep mode and not using any energy when you're not shifting.

The Di2 battery lasts from between 600 to 1,500 miles between charges. You can expect that lots of shifting in cold, cold weather will result in shorter battery life, but we've found that 1,000 miles is an average interval. There is no "charge memory" in the battery, so you can recharge it as often as you like, though Shimano recommends once a week or so if you're a daily rider. The battery can go 300 charge cycles at 100% integrity; charging once a week means almost six years.

Wondering about getting a second battery, "just in case?" We asked Shimano. They say it's only a good idea if you think you're really going to go over 1,000 miles between opportunities to charge the battery. And, if you somehow miss all the warning signs and run the battery down in the middle of a ride, your bike will stay in the gear it was in when the battery died. You'll have to replace or recharge the battery to move the derailleur once again.

The Shimano Di2 Battery operates on 7.4-volts and is easily recharged with the Di2 charger (not included). Once discharged, it takes 1.5 hours for the battery to receive a complete charge. It uses lithium-ion technology to maximize output and minimize size.

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Here's what others have to say...

4 5

Works as OEM, cost more than my car batt

  • Familiarity: I've put it through the wringer

I lost my initial battery after about 500 miles on a rough road. I bought a replacement and it has worked just as well. I charge it about every 500 miles.

I would give this product a 5* except for the pricing. My car battery costs less. This is shimano charging a price premium for their branding.

2 5


  • Familiarity: I've put it through the wringer

My initial battery life was exceptional. However, once it was depleted it fails to hold a charge for more than 75-100 miles. It has become routine for me to spend significant time during my rides stuck in whatever gear I was riding when the battery died. This happens despite showing green on the battery indicator light at the start of the ride.

5 5

better than aftermarket

  • Familiarity: I've put it through the wringer

After using aftermarket batteries I have come back to this external mounted unit for its continuous ability to always be reliable. It just plain works!

4 5

better keep an extra

  • Familiarity: I've put it through the wringer

my fault i got caught out - these systems need a continuous led readout