LFP house to LFP starter charging

[Drennan]

We are in the process of installing LFP replacements for our Gozzard’s AGM banks. I thought I could solve the final charging issue (14.0v house-battery charging > 14.6v starter-bank charging) with the boost function of the Sterling “Pro Batt Ultra” dc-dc charger; however, Amazon reviews and forum complaints indicate reliability & support could be a problem.

Another possibility might be a Victron 12/12/18-30A converter, SmartShunt, and manual activation. Cost would be about the same as the Sterling unit, but w/o automation.

1) Any shared wisdom with respect to Sterling, Victron, and alternative units or approaches is appreciated.

2) If I postpone/forego automated monitoring (SmartShut, etc.), how do I know when the starter bank LFP is charged near 100% SOC? Have I read that a charge-amperage decline to 3-5% of Ah capacity is indication of near-full charge? Thus a simple clamp-meter reading?

Thank you