Di2 battery issues

My DI2 battery started losing charge over a 6 week period eventually giving up the ghost. The battery is 3.5 years old and I didn't have a single problem in that time. A new £100 battery BT-DN110 (internal) has solved the issue. The old battery had an odd smell about it but was not leaking and there was moisture around the connection point and around the rubber seat post fitment which I reckon came from washing the bike upside down which allowed water into the seat post via the bottom bracket dainage hole. Cause and effect? Either way this is a bad idea if you're running DI2.

Also bought a new D-fly to take advantage of the etube app for iphone. Some useful functionality and it shows you all connected DI2 components so if you have a connection issue then that component will not show up. It also enables multishift & other stuff. Annoyingly the shimano app tells you to enter 000000 to pair bluetooth to DI2 via D-Fly which simply does not work. You must first connect di2 to a windows laptop to set the bluetooth pairing code and most likely update the firmware. After that you can then bluetooth the etube app to bike using the iphone without the need. for a laptop.  Remember to proactively disconnect the bluetooth on your phone otherwise DI2 will stay in adjustment mode which means it won't respond to any shifter inputs and you'll think you've killed it. 

You haven't been using it to power your crankset, or your jockey wheen have you?  That will wear it out in no time!

The battery can go 300 charge cycles at 100% integrity; charging once a week means almost six years. Shimano will replace at n/c with receipt of proof of purchase. To verify the issue follow what kev-s mentions.

Not charging the battery often shouldnt make any difference

best bet is to check the wiring and try switching the battery with a friends to see if thats the issue

also email shimano's uk distro madison explaining the situation and that your lbs have checked and cant find the fault

They maybe able to help or offer a new battery

Id do a connection check on the battery and junction box b to make sure the wire is fully seated and the wire has no damage

It maybe just a case of the wire has managed to come a little loose

Also the mech could be slightly out and its trying to shift which will drain the battery

Find somewhere quiet and shift the bike into the largest sprocket at the back and see if you can hear the rear mech still trying to shift,  do you hear the mech's motor quietly clicking away?

How old is the groupset? as if its less than 3 years old and the battery is faulty then shimano will replace it under warranty (3 years for Dura Ace & Xtr, 2 years for Ultegra)

If you do get a replacement battery from shimano or anywhere else ask them to update it to the latest firmware then update your bike to the latest firmware before you fit the new battery

If you dont do this then you may have issues and you will need to make a trip to your local bike shop for a update with the sm-pce1 diagnostic tool just on the battery on its own (you cant do this with the bcr2 charger/pc interface on individual components)

If you dont do this you might find once you fit the new battery  that your groupset has firmware version 4.2 but the new battery has firmwire version 3.9 so wont work until the battery has been updated, if the battery is  on version 4.0 or above and the groupset is version 4.0 or above then there shouldnt be any problems

Had this problem a little while ago on a gearkit upgrade for a customer (still using the bikes original battery and wiring) luckily i have the sm-pce1 diagnostic tool at home

Yes it is easy to disconnect and change. If it is in the seat tube then there is usually a circlip holding it in that needs circlip pliers to get it out (and obviously a Di2 wire to be disconnected, ideally with a small plastic Di2 tool that should have come with your bike, but it is possible to disconnect my hand - provided you don't try just yanking the cable to do it - only hold the plastic plug at the end of the cable)

However it is unsual for a battery to die so quickly all of a sudden.

How often do you charge it?  (only when it is flashing half way or when it gets to red?) when is that? (every 3-6 months?)

One issue I found is that if you have something obstructing the movement of either derailleur it can quickly drain the battery. Usually still takes more riding than two days but it does depend how much you changed gear in those two days. Have you adjusted the end-stop screws on either derailleur recently?

What caused my problem, was, I adjusted the FD screw to force the chain onto the larger chainring after the battery went into limp mode and I had a long descending road home. Once home I adjusted it back (and charged the battery) however I had not adjusted it back enough and every time I changed gear on the FD, the motor was running against the stop-screw. 3-4 rides later it was showing the battery very discharged. Realised it must be the screw - set that correctly and battery life back to normal.

I've not had any issues myself, but one thing I have read is that you need to ensure the firmware matches across all the components - a replacement battery might end up with newer firmware.

I'm not sure how hard this is, it may be easiest to have the LBS replace the battery and flash all the firmwares for you.  You can do this yourself (apparently) with a windows machine and the charger cable that came with it - but I've no practical experience of this - I've left well enough alone with mine.