The WF-9855 Thor used in my Magnitude does not call out Lithium Batteries as supported. That is probably the 80-90% charge aspect. WFCO does offer the WF-9855LiS, which is designed for switching between Lead Acid and Lithium.
The Progressive Dynamics PD9260 I replaced the WF-9855 does not support Lithium but I was ok with it because I don't have plans to go that route. They have a 9100L series for Lithium.
Here is a good video that overs Lithium Battery charging for RV's you may find useful.
Thor Forums
