Hello Jonathan. Welcome to the forum. Where in the world are you? Are you on the
www.ev-network.org.uk/ ? (Obligatory joining questions out of the way
There are several lithium PSA vehicle conversions underway/completed, and every one has been done differently.
Is your motive purely availability of spares? This is a good enough reason in itself, but the Ni-Cads are very robust when they are working, where lithium needs constant baby-sitting.
A commercial company doing the conversion would have many takers, I think. My own project is proceeding interminably slowly, as my cells rot away in the garage...
I will be interested ton hear what sort of reception you get from Jukka at FEVT. His company was not planning to cater for home-builders, but your commercial venture might get his interest. His own Berlingo was a development vehicle for the system he sells.
Evan Tuer has succeeded in integrating his own cell protection with the SAGEM controller you have under your bonnet, even to the extent of re-programming the charger for the correct regime needed for lithium. I chickened out and bought a separate charger, but may use his system in the future, once I am on the road.
That will do for starters. I hope your ideas spark interest with others.