I got 8 x 40ah LiFePO4 cells for my little Vienna chair. And I regretted it because at 11.5kg it is almost as heavy as the lead was and completely unmanageable. So when I use my big heavy outdoor chair that I don't like, it will have to be an add-on pack for that.
Meanwhile I am letting my bank account recover from the encounters with
1 which is a bit fraught, but interesting) battery building, and
2 which is worse and totally pointless) Motability
Then I'm getting some 12ah cylinder cells to put in the original battery case and I'll see how that goes. And I've reverted to the original seat for the chair, as the seat post weighed so much that it wasn't worth it with the lightweight replacement, freezing my butt off and going without the headrest and tilt.
I'm in no rush. As usual, I'm short of energy for messing about with wheelchairs. I'm considering with dismay the prospect of tightening the loose hinges on my mother's window.