Someone mentioned this thread, so I'm jumping in mid-stream. Pardon if I missed some context.
Regarding "load dumps"... there may be some well known BOAT concerns creeping into some RV discussions. BOATS are famous for having multiple battery banks behind a big "A":"B":":"A+B" red selector switch, in part so one battery bank can sit disconnected in reserve. If the selection switch is used while the alternator is running, the alternator can be toasted by 100VDC+ voltage spikes when a load dump occurs between the switch breaking and making contacts. With the introduction of LiFePO4 batteries with BMS's that can suddenly disconnect, this general class of topic is starting to come up more and more in the RV world.
Without a more modern charger in the mix, spikes towards your alternator and your RV electronics can occur when a BMS disconnects. I don't know if having a lead acid battery in the mix (next to the alternator) partially or fully clamps the spike. Sterling's alternator protector is just a voltage clamp device.
Here is someone's attempt to better explain the load dump problem (~2/3rds down in the article). It is sales pitchy, but some of the points are good.
https://marinehowto.com/understanding-the-sterling-power-pro-batt-ultra-battery-to-battery-charger/
Wrt other merits of a DC-to-DC charger. I posted the following to a nearby forum.
FLA batteries start to accept a charge and pull amps at 12.6V, but LFP batteries start that process at 13.6V, a whole volt higher. Depending on your alternator's voltage output and the voltage drop in your wiring, LFP could charge SLOWER than FLA, and FLP charging could fail to reach 100% SOC where-as FLA could.
With my 45A Progressive Dynamics Inc charger running in FLA mode, my old ~200Ah of FLA would pull 18A over 10ga wiring. Still running in FLA mode, my 200Ah of BB LFP at 30% SOC only pulls 4A over shorter and bigger 8ga wiring. Putting the charger into boost/LFP mode (boost the voltage) increases the pull to 39A. Point being, same charger, the LiFePO4 charge rate is 1/4th the flooded-acid rate.
Sterling (maker of DC-to-DC alternator chargers) has some nice videos on YouTube where they wire LFP direct to an alternator with ~4ga wire, and the charging rate is pathetic. Then they insert a DC-to-DC charger in the line and the charge rate jumps substantially, because the charger can re-boost the voltage.
All in all, current is pulled based on volts being delivered. For 7-pin systems, the Achilles heel is voltage. Solve the voltage problems first, and then you can start to worry about the current problems next.
--tg
