Di2 battery on an ebike?

[Xmouth]

Hi all,
I have a custom ebike which I want to switch over to Di2 IGH.......it seems crazy to add a Di2 battery when I already have a battery on the bike. Does anyone envisage problems if I use a buck converter to reduce from 48V to 7.4V to power the Di2?
Thanks

 

[fechter]

I didn't see any electrical specs for that hub. It should work with a dc-dc, but it may have a fairly high current spike when it's shifting. You may need a large capacitor on the output of the dc-dc to handle the spike.