# Di2 Sudden Power Failure



## TiCoyote (Jun 28, 2005)

I was riding yesterday afternoon, and my shifters suddenly stopped responding. 

I have Ultegra 6870 Di2 with an internal battery. I was 10 miles into a ride on a hot day, and all of a sudden it simply stopped responding. Pressing the button on the Junction A box did not activate the light. 

I pulled out my seat post and found that the battery had slipped down into the seat tube. I flipped the bike over and after some shaking, got the battery back out. It was still connected to the wire. I unplugged it and plugged it back in, but there was still no response. 

Then I unplugged and replugged the wires into the rear derailleur, front derailleur, and junction-A box, and I checked the wires at the shifters. None of these made any difference. 

Eventually, I just gave up and got back on the bike, resigned to riding without shifting. After about 1 min, the shifters sprang back to life. 

I checked the battery light, and it's solid green. 

The bike rode fine for the next 14 miles. When I got home, I unplugged and replugged everything, including the wires at the B-Junction. Nothing felt loose. I also noticed that unplugging a single shifter or derailleur doesn't stop the other one from functioning. 

I plugged it into the e-Tube software and everything was recognized (the B-Junction didn't show up, but I don't think that it would anyway. Let me know if I'm wrong about that). 

The battery is set in the seat post with some packing foam. I ordered the Ritchey mount to avoid the battery dropping down again. I'm not sure that this was the issue, and the battery could have certainly dropped down ages ago. But it's a good precaution. 

I guess I could go a to bike shop and have them run a diagnostic if it happens again. Please let me know if anyone has any other suggestions or things to check first.


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## Notvintage (May 19, 2013)

TiCoyote said:


> Please let me know if anyone has any other suggestions or things to check first.


Go buy Campy SR mechanical. It's brilliant and uses no batteries.lol


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## cxwrench (Nov 9, 2004)

Oddly enough I just got a bike in today that had the same thing happen. Customer went to Italy, road for 5-6 days then bike just went dark. Nothing worked, no LED's, nothing. Unfortunately it was August in Italy so the entire f'ing country is on vacation including any bike shop that might have the slightest clue about Di2. I just hooked it up to e tube and got nothing, so now I have to take the damn thing apart to figure out that there is probably a bad wire somewhere.


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## TiCoyote (Jun 28, 2005)

cxwrench said:


> I just hooked it up to e tube and got nothing, so now I have to take the damn thing apart to figure out that there is probably a bad wire somewhere.


Maybe not. I figure that the only bad wires that would knock out the entire system would be 
-Junction A to Junction B
-Battery to Junction B


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## cxwrench (Nov 9, 2004)

TiCoyote said:


> Maybe not. I figure that the only bad wires that would knock out the entire system would be
> -Junction A to Junction B
> -Battery to Junction B


Prob A to B on this bike, which is a Calfee w/ S&S couplers. At this point I have no idea where the B junction box is


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## duriel (Oct 10, 2013)

To the OP, please be aware that the Di2 connectors I have have '2' clicks when you push the wires into the FD & RD. When I originally installed them, I just went put them in till they clicked, the system started to get intermittant shifting, then I learned about the second click. All is well now... for me.


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## Notvintage (May 19, 2013)

And to add, mechanical works 100% of the time unless a cable broke. And going on a holiday trip with a battery operated drivetrain is just stupid.


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## duriel (Oct 10, 2013)

Notvintage said:


> And to add, mechanical works 100% of the time unless a cable broke. And going on a holiday trip with a battery operated drivetrain is just stupid.


There are a lot of stupid people out there, but I don't think riding with Di2 is that big of deal unless you are one.


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## TiCoyote (Jun 28, 2005)

Notvintage said:


> And to add, mechanical works 100% of the time unless a cable broke. And going on a holiday trip with a battery operated drivetrain is just stupid.


I'm not interested in your opinions about Di2.


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## tlg (May 11, 2011)

Notvintage said:


> And to add, mechanical works 100% of the time unless a cable broke. And going on a holiday trip with a battery operated drivetrain is just stupid.


I agree. If your holiday trip includes over 1,000mi of riding, it would be stupid. Of course if that were the case, you'd just take the battery charger with you. Very simply solution.

I'm sure when you go on holiday you take spare cables.


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## 202cycle (Sep 13, 2011)

I've seen this on two bikes, mine and a customers. The failure was in the wiring harness from the shifters to the junction box. Replaced and bingo all was well.


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## TiCoyote (Jun 28, 2005)

202cycle said:


> I've seen this on two bikes, mine and a customers. The failure was in the wiring harness from the shifters to the junction box. Replaced and bingo all was well.


Can you post a link to the part you replaced? Thank you.


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## 202cycle (Sep 13, 2011)

TiCoyote said:


> Can you post a link to the part you replaced? Thank you.


MY bad on this one, those were 6770 with the wiring harness/junciton box. best of luck


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## Srode (Aug 19, 2012)

Notvintage said:


> And to add, mechanical works 100% of the time unless a cable broke. And going on a holiday trip with a battery operated drivetrain is just stupid.


I would bet a higher percentage of people using mechanical set ups have had issues with broken shift cables while riding than those riding Di2 bikes have and non working Di2 set ups. Even if you forget to charge them, it's the front DR that goes first then rear. With mechanical most broken shift cables are on the rear due to the frequency of shifts, and I would much rather have lose use of the front than the rear.


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## TiCoyote (Jun 28, 2005)

I am not interested in a debate between drivetrains. I am just looking for suggestions to fix mine.


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## cxwrench (Nov 9, 2004)

Srode said:


> I would bet a higher percentage of people using mechanical set ups have had issues with broken shift cables while riding than those riding Di2 bikes have and non working Di2 set ups. Even if you forget to charge them, it's the front DR that goes first then rear. With mechanical most broken shift cables are on the rear due to the frequency of shifts, and I would much rather have lose use of the front than the rear.


^This^ You can always tell when someone posts w/ complete ignorance of the electronic drivetrains by saying 'Buy XXX mechanical'...generally the Di2 problems are few and far between..._everyone_ will fray/break shifter cables if they wait long enough.


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## Z'mer (Oct 28, 2013)

It is very probable you have an intermittent break in one of your wires. Probably the one from the battery. This is fairly common in copper wire that is subjected to constant bending back and forth (from vibration). 
I've tossed out at least a dozen cheap headphones used for running, that over time developed internal wire breaks. 
You can test the wires with a multimeter, and measure end to end resistance while bending the wire in every possible way. Usually the break occurs very close to the rigid connector area.


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## TiCoyote (Jun 28, 2005)

Z'mer said:


> It is very probable you have an intermittent break in one of your wires. Probably the one from the battery. This is fairly common in copper wire that is subjected to constant bending back and forth (from vibration).
> I've tossed out at least a dozen cheap headphones used for running, that over time developed internal wire breaks.
> You can test the wires with a multimeter, and measure end to end resistance while bending the wire in every possible way. Usually the break occurs very close to the rigid connector area.


This is a good suggestion. It may have happened at the connection to the battery, since the battery was sitting in the seat tube, probably putting major strain on the wire.


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