Why stay away from Renogy? I haven't had a chance to test mine yet, but there is a 40A Renogy DC-DC charger in my setup.
Both of the Renogy DC-DC chargers I had would continuously and randomly shut off when trying to charge Lithium batteries. Renogy customer service is terrible. You wait on hold for a long time and just talk to some kid who has no idea what they are talking about and reads back a script from a computer screen.
The Renogy DC-DC chargers seemed to work fine with AGM and Gel.
I would recommend charging straight off of the alternator/starting battery via a BlueSea relay, or go with a Sterling unit.
Edited by ClimberRob, 21 August 2019 - 01:07 AM.