Roadbike , carbon post, Di2 battery in it in bung. Last put back together a while back and battery was in bung at end of post. Had cauase to take it apart as it stopped working and lo the blinking battery has disappeared off up the seatpost, its a good 3″ up there and I can’t think of a way to get it back out and/or plug it all back in. Any smart ideas ? Only one i have is drill a hole in the top of the seat post and try and shove it back down to get it out. Or buy a new seatpost, battery and bung which is last resort stuff !

Some carefully placed oil and a whippy wrist action onto a covered bed/sofa soft thing?

Put it in the freezer. The rubber and the battery will contract more than the post. Remove and apply some light lubricant and whip it free.

Take the saddle and clamp assembly off, there’s sometimes (I stress “sometimes”) a hole that will allow you to push from the top.

Melt the end of a glue stick with a lighter, stick on, tug?

This above. Although I’d do it with a hot melt glue gun (why have you not got one) Blob hot glue on stick/metal rod, poke up post to battery, let set and gently pull it out. Then peal off the glue.

How good is your hoover?

Trip to A&E and say you slipped in the shower

Had this once before, i used a thin pair of long nose pliers to grab the bottom of the battery and pulled it out the seatpost

Worst case, remove the saddle and seatpost guts, drill a small hole in the top of the seatpost and poke a old spoke though it to push the battery down

One of these any good?

Another option if the post is indeed sealed could be to use something like a sealant syringe to create a vacuum in the post and try dislodge the battery downwards.

Would be a bit of a challenge sealing the hose up but worth a go if all else fails.

Shove a spoke up there (I speak from experience). Also done a stick with hot glue when another one went down the seat tube.

Trip to A&E and say you slipped in the shower

avdave2 wins