Custom internal battery pack for Dura Ace DI2

Custom seatpost Di2 battery

How to build an internal battary for Shimano Dura-Ace  DI2 7970 and Shimano Ultegra DI2 6770.


Custom build DI2 battery

Note this is not compatible with the E-Tube system.


Instructions

DI2 wire colors

This is how it might look when you are done

Step 1
Sold the batteries in serie (3.7V + 3.7V = 7,4V). Layout the wires so they end-up in the same direction. Connect an female powerconnector. Use heat shrink plastic tube to wrap it all into an batterypack.

Modified powercable

Step 2
Extend the cut DI2-wire with new wireing in length of you seatpost tube and sold an
male power connector in the other end.


Custom powercabled connected to the junction

Step 3
Install the custom DI2-wire in the frame.


Custom batterypack installed in seatpost (with foamplastic) and connected
to the junctionbox with the custom powercable

Step 4
Connect the batterypack to the wire and testout the function of the DI2 shiting system. If all works ok please contine otherwise debug the setup...

Step 5
Slip on the shrink tubing on the battery pack and heat it to shrink. Make sure the power connector are in place while doing this.

Summary
Relativly easy build. The performance of this custom power solution is superior to the external battery solution provided from Shimano. This kit deliver 1800 mAh of power compared to 530 mAh from Shimano SM-BTR1 batteries.

Parts used

TrustFire 14500 3.7V 900mAh Lithium batterys

• 2 x TrustFire Protected 14500 3.7V 900mAh Rechargeable Lithium
• Shrink tube, 16 mm




Molex connector 0306-1023



Molex connector 0306-2023

• Power connectors
• I used Molex 0306-1023 and 0306-2023
• One DI2-cable with connectors for the juction box
• I had one spare so I cut one to get the connector
• Some wireing
• I used 0.14 mm wires




Lithium battery charger

• Charger for Li-ion batteries
• I used this one "Smart Charger 8.4V 1A for 7.4V 7.2V Li-ion Li-po Battery Auto-Stop"