Remove a stuck Di2 battery from a seatpost
Are you trying to take out a Di2 seatpost battery? Is it stuck? Before you take your pliers to it and ruin the battery or the seatpost itself, try using a J-bend spoke instead.
Whether you run 11-speed Di2 or 12-speed Di2, chances are pretty good that you have a seatpost battery - either the BT-DN110 10-/11-speed or the BT-DN300 (12-speed).
If you do, you could tuck away the battery in the seatpost using a piece of cloth or foam and be done with it. Alternatively, you can install a seatpost battery holder.
I tend to use the battery holders, just because I like my battery to be really secure. They're relatively inexpensive and work really well.
I'm using a Deda battery holder in my BetterShifting Cinelli, but any will do, really.
PRO make them, as well as Deda, Ritchey, Cannondale, Giant, and many others.
Most will fit round seat posts, and come in different diameters. Make sure you get the one that matches your seatpost. If your seatpost isn't round, double-check with your bike's manufacturer.
Are you trying to take out a Di2 seatpost battery? Is it stuck? Before you take your pliers to it and ruin the battery or the seatpost itself, try using a J-bend spoke instead.
Learn how to install your Di2 BT-DN300, BT-DN110 or SM-BTR2 battery in your bike's seatpost.
Watch me build up my Cinelli Veltrix Disc with a full Di2 R8050 Ultegra groupset and the Shimano FC-R9100-P Power Meter.