DC to DC Converter or a Battery Isolator?

Question:

Hey Jeff, like many of your followers I own a sailboat with a bigger battery bank for the house than for the engine.  Currently my batteries are lead acid (Trojan) for the house battery and an AGM for the engine.  Following your advice that an ACR works better when house and engine batteries are equivalent capacity. Thus, I was looking to install a battery isolator to manage the charging of the battery banks.

Soon I’m thinking of converting the house battery bank for LiFe or LiPo. The tech at Battery world suggested DC to DC charger. Is the battery isolator a good (or the best option) or it would be better to use a Victron Orion 12/12-30 charging unit? - Martin

Answer:

Considering that you'll go with Lithium for your house, a DC to DC charging converter is best suited to charge different battery chemistries (AGM and LiFePO4).  Remember a battery isolator only shares a charging voltage from the alternator, but it does not modify the voltage for each battery chemistry.