I had this BcDC in my 4runner for 2 1/2 year works perfectly it powered my auxiliary battery and other accessories. I’m throwing in an battery monitor from Ironman 4x4 for free(worth about $100).

It was in use until I sold the 4runner and I’m going in a different set up for my current rig.

The REDARC BCDC1225D In-vehicle Dual Battery Charger is a 12 volt, 25A in-vehicle DC-DC battery charger designed to charge your secondary battery banks to 100% state of charge while on the move