Shimano Di2 SM-BTR1 Battery

The Shimano Di2 SM-BTR1 Battery is the external power source for Shimano's Di2 electronic groupset range — a compact, rechargeable unit designed to keep your shifting system running reliably across thousands of kilometres. It mounts to the bike via a SM-BMR2 Battery Mount and is compatible across Di2 generations.

Expect roughly 1,000–2,000km per charge under normal conditions, though that figure shifts depending on how frequently you use the front derailleur, ambient temperature, and overall shift volume. The system gives you advance notice before power runs out — a warning light on the junction box appears first, followed by loss of front derailleur function, leaving you with an estimated 100–200 rear shifts before the battery is fully depleted. Charging from empty takes approximately 90 minutes using the SM-BCR1 charger and power cable. The battery is rated for around 300 charge cycles before capacity begins to decline, which works out to well over a season of regular riding before you'd notice any difference.

Shimano Di2 SM-BTR1 Battery Specs at a Glance

• Compatibility: All Di2 generations (requires SM-BMR2 Battery Mount)
• Estimated range: 1,000–2,000km per charge
• Charge time: Approximately 90 minutes from empty
• Cycle life: ~300 charge cycles before capacity degradation
• Charger required: SM-BCR1 Battery Charger and SM-BCR1 Power Cable (sold separately)