Di2 external power

[Deere John]

Hi!

I would like to fit XT Di2 on my ebike with regular battery. Feels like it would be wasted with a Di2 battery when I already have a big battery for motor. I only need a 36V to 7.4V converter. But that is something I would like to get anyway for lights.

Is that possible? I mean, easy, only +/- wires and no data signal of some sort?

What voltage level does it take, I guess 8V is ok at least?

Is there any junction box that is better/worse for this? I need only one derailleur, one shifter. Hide the junction box in a frame bag.

Need some advice here, it is a jungle this

 

[vfr400]

A normal Di2 doesn't work very well with a crank motor because of the tension on the chain and the fast shifting. Any gear sensor that you have will be over-ridden because there is no shifter or cable to sense. It looks like there's a special Di2 for ebike motors that integrates with the control system. AFAICS, it doesn't have its own battery.

https://si.shimano.com/pdfs/dm/DM-EX0001-02-ENG.pdf

I tried a Bafang HD with Di2 fitted. It wasn't very comfortable regarding the shifting. It worked, but I had a feeling that something was going to break sooner or later. Have you already tried a Di2 on a CD bike?

 

[Deere John]

yes, I have considered that too. But I have a wheel motor so it should be no problem.

I found a mighty interesting page on DIY battery pack for the (old) standard Dura Ace Di2:

Custom internal battery pack for Dura Ace DI2

En blogg om att träna inför och genomföra en svensk klassiker

tomasklassiker.blogspot.com

And this video:

 

[vfr400]

That DIY guide is a bit dodgy because there's no cell balancing, which could cause the battery to catch fire when charging. He should have used a 2S balance connector instead of the one he used so that he could add the cell-tap between the cells and a 2S lipo charger to balance them. In fact, it would have been better to use a long thin 2S lipo pack than those 18650s.

Turnigy nano-tech 1200mAh 2S 25-50C Lipo AIRSOFT Pack

Turnigy nano-tech 1200mAh 2S 25-50C Lipo AIRSOFT Pack

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