Battery Charging Problem ***UPDATE***

LOG wrote:
It appears that your motorhome has the voltage drop problem that DrewE was explaining. And has nothing to do with a "smart" charging system.
Maybe you need a better battery isolation manager or combiner.

LOG,

I have dual charging paths with #8 wire (rating 50 amps) with dual solenoids, each rated at 200 amps continuous. I have manual control of the solenoids and charging from the alternator. Each charging path is protected by a 50 amp automatic circuit breaker.

If the house batteries are "hungry", then I see more than 75 amps of charging. (my meter only reads to 75 amps). On occasion I've observed at least one of the circuit breakers flipping off and then on.

On normal use, because my starting battery is given a maintenance charge when ever the sun is shining, I see little charging after the starter battery is full from the ecm's point of view.

I can "force" charging of the house bank by using the inverter and running the 1400 watt water heater. However this does, after about 20 minutes, cause the starter battery to go down to 12.3 volts. At that point, I use my manual control to stop the charging, and I disconnect the water heater. The reason for doing so, is the 1/3:2/3 duty cycle on the alternator which I do not wish to burn out.

After 40 minutes of highway driving, I can repeat the above process. The last hour of driving I use to return some charge to the house bank.

I can "see" one of the breakers flipping in and out if I run the engine and use the microwave (170 amps draw) and the induction cooker (70 to 130 amps) at the same time.

These observations are from 2013 when I had 8 identical marine jars, one of which was used as a starter battery, and the house banks were configured as 3 and 4. Both banks were wired in a balanced manner. The "house" bank was 875 amp-hours @ 12 volts.