Older Endurace seat post and Di2 battery

I have a 2020 or 2021 endurace that I’m planning to put di2 group onto. I want to put the battery in the seat post (it’s the SP43 post). I’m reading that you can’t put the battery in the endurace seat post but I’m assuming that’s only for the newer split posts. The seat post I have is just a round tube (see pics). I’ve never installed di2 before so just making sure this will work before I start.

Thanks!

by word_sa1ad