Technical 2005 2.0JTD Lithium upgrade

[nosmo]

So I am wanting to upgrade my leisure battery to lithium
This is the current setup

I'm not 100% sure but this is how I am thinking it works
The 240v input is from the EHU to provide power to the silver box (charger/240v/12v power converter?) to A: charge the leisure battery and B: power the converter to give 12v into the fuse box you see to the left of the silver charger
The leisure battery is connected back into the fuse box to feed the 12v when no 240v is connected?
So what do I do here, do I just change the existing charger box and replace it with a DC/DC charger leaving the 240 input disconnected as will be using alternator and/or solar to keep it charged
Is it that simple or more involved than I am thinking?
Sorry for the noob question but I cant see much info about these chargers online

 

[NeilDD]

@nosmo To charge the habitation battery from the vehicle you use the B2B charger
To charge the habitation from an EHU you need a lithium compatible mains charger, with enough headroom to supply the 12V domestic lighting etc.

I'm just about to start a similar upgrade on my later 2019 van,