Di2: Can a "False Shift" Drain the Battery?
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  1. #1
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    Question Di2: Can a "False Shift" Drain the Battery?

    I got on my bike, now mounted on my Wahoo Kickr trainer, to ride on Zwift the other day only to be surprised that my Di2 battery was completely dead. This was a surprise because I had just ridden the bike a few days before and had over 50% battery capacity. This got me thinking about how on earth the battery could've been drained so quickly when I wasn't even riding the bike.

    If one clicks the Di2 rear shifter to shift a gear but the rear wheel isn't moving, hence the chain isn't moving either, could this potentially put Di2 into a weird state where it's 'trying to shift' but can't, thus draining the battery?

    Since my bike is sitting on a Wahoo Kickr trainer, I'm wondering if I accidentally hit the shifter when not pedaling as I got off the bike. That would've given Di2 plenty of time to drain the battery as it attempted to shift for days(?)

  2. #2
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    It'll do it with the FD, and probably with the RD too. Hence that remark in the Di2 literature about always be pedaling when shifting*

    *Among other reasons
    "We are doomed to live in very interesting times"

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    Quote Originally Posted by Marc View Post
    It'll do it with the FD, and probably with the RD too. Hence that remark in the Di2 literature about always be pedaling when shifting*

    *Among other reasons
    I'm an engineer and a guy... I don't read documentation

  4. #4
    tlg
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    Were you in the large or small cog? I've heard if the limits aren't set right and you shift, the derailleur keeps trying to move and drains the battery.

    In the middle of the cassette, I can't see this happening. In all the years I've had Di2 I'm sure I've done this at some point, whether in the repair stand or on the trainer. I've never had a drained battery.

    I've also heard some firmware can cause battery drain issues so make sure you're updated.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

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    Quote Originally Posted by PoorInRichfield View Post
    I'm an engineer and a guy... I don't read documentation
    DCR's review of the Kickr said something in the unboxing like..."And here's the documentation that, let's be honest, none of you are going to read..."

    Although, TBH, the included documentation basically tells you about the axle adapters...and for the v5 the feet....and that is it.
    "We are doomed to live in very interesting times"

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    Quote Originally Posted by tlg View Post
    Were you in the large or small cog? I've heard if the limits aren't set right and you shift, the derailleur keeps trying to move and drains the battery.

    ...

    I've also heard some firmware can cause battery drain issues so make sure you're updated.
    Unfortunately, I don't know which cogs or chainring the bike was in... I didn't realize I had no battery until I had already pedaled a few miles in Zwift Per Marc's comment, I suppose it's possible I had clicked the front derailleur button as well by accident.

    Ironically, I had just downloaded the latest e-Tube v4.0.2 for Windows and just did a firmware update before this battery drain thing happened.

  7. #7
    tlg
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    Quote Originally Posted by Marc View Post
    It'll do it with the FD, and probably with the RD too. Hence that remark in the Di2 literature about always be pedaling when shifting*

    *Among other reasons
    Oh wow... it does say that.

    Notice:
    Be sure to rotate the crank when carrying out any switch operations which are related to gear shifting.

    Technically, you shouldn't do that on a mechanical derailleur either. But is that to prevent damage or for battery drain? It doesn't say.
    Many times I've done this with the bike in the stand or when changing a wheel with zero issues.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  8. #8
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    Quote Originally Posted by Marc View Post
    DCR's review of the Kickr said something in the unboxing like..."And here's the documentation that, let's be honest, none of you are going to read..."
    I have a v1 Kickr, so even if I had read the directions I certainly wouldn't remember them by now (or even know where the are). I just got Di2 this year so I've been going through the whole Di2 learning curve since this Spring. Most of the time I love it, but I pretty much think batteries are the root of most evil these days.

  9. #9
    tlg
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    Quote Originally Posted by PoorInRichfield View Post
    Ironically, I had just downloaded the latest e-Tube v4.0.2 for Windows and just did a firmware update before this battery drain thing happened.
    I'd google the firmware version and "battery drain".
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  10. #10
    tlg
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    Quote Originally Posted by PoorInRichfield View Post
    but I pretty much think batteries are the root of most evil these days.
    While I agree with you... the Di2 batteries are pretty great. If anything they last too long and you forget to charge them.

    I have the wireless Unit on all my bikes which gives battery percentage on the Garmin.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  11. #11
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    Quote Originally Posted by tlg View Post
    Oh wow... it does say that.

    Notice:
    Be sure to rotate the crank when carrying out any switch operations which are related to gear shifting.

    Technically, you shouldn't do that on a mechanical derailleur either. But is that to prevent damage or for battery drain? It doesn't say.
    Many times I've done this with the bike in the stand or when changing a wheel with zero issues.
    With the FD, it takes a couple crank revs to complete the Di2 trim cycle. So if you're like me, and live at the top of a rise steep enough to want to dump the front chainwheel....and are like me and lazy and would rather just park the bike and be ready to go next time and be on the dinner plate....beware leaving enough crank revs to complete the trim before parking....otherwise Di2 will stay awake and drain the battery.

    That ofc is the FD....RD is an entirely different animal in terms of design, but I believe the same rules apply of the RD where if it feels resistance to its motion completing it'll keep fighting it. I think the FD is a linear motor, whereas the rear is a servo(?)
    "We are doomed to live in very interesting times"

  12. #12
    tlg
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    Quote Originally Posted by Marc View Post
    So if you're like me, and live at the top of a rise steep enough to want to dump the front chainwheel
    I live in a valley
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

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    Quote Originally Posted by PoorInRichfield View Post
    Unfortunately, I don't know which cogs or chainring the bike was in... I didn't realize I had no battery until I had already pedaled a few miles in Zwift Per Marc's comment, I suppose it's possible I had clicked the front derailleur button as well by accident.

    Ironically, I had just downloaded the latest e-Tube v4.0.2 for Windows and just did a firmware update before this battery drain thing happened.
    It probably isn't your fault. E-Tube 4.0.2 is very buggy and half of the time it does NOT actually disconnect when you tell it to, causing the battery to drain.

    I have written a page on this right here ;-) https://bettershifting.com/e-tube-pr...bugs-overview/

    GPLama had some people comment on his videos with the same issue and he experienced the issue himself too.

    TLDR: You can safely use E-Tube 4.0.2, but after you disconnect make sure the bike actually shifts. If it doesn't, reconnect and then disconnect again.

  14. #14
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    Quote Originally Posted by PoorInRichfield View Post
    I have a v1 Kickr, so even if I had read the directions I certainly wouldn't remember them by now (or even know where the are). I just got Di2 this year so I've been going through the whole Di2 learning curve since this Spring. Most of the time I love it, but I pretty much think batteries are the root of most evil these days.
    You misspelled 'cliff'.

    I love my Di2...but Shimano's documentation for the entire system is piss poor for the electronics and firm/software. Did I say piss poor? I meant non-existent. They basically pulled a Garmin and outsourced all the development to the community to figure that crap out.
    "We are doomed to live in very interesting times"

  15. #15
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    To answer the original question: a 'false' RD shift should not drain the battery.. It'll try for ~5-10 seconds and then just give up.

    I'm not sure about the FD

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