I am now sure that the relay I mentioned in the first post of this thread is something extra added to the Intellitec Battery Control Center. See attachment 1.
It is easy to see that this extra relay connects the chassis and coach batteries together whenever the ignition switch is ON. This relay is definitely not needed and because of the small wire size can be dangerous.
This a quote from the Intellitec Battery Control Center Manual:
"The charging circuit, (which utilizes an isolator solenoid to connect the two batteries together for charging) will charge both batteries if either battery is being charged. It operates by sensing the voltage on the main and auxiliary batteries. If either voltage goes above 13.3 volts (the minimum necessary to fully charge a battery) for more than about 14 seconds, the isolator solenoid will pull in, charging both batteries. If the voltage falls below 12 volts for more than 4 seconds while the ignition is on, the isolator relay will open, keeping all of the alternator's output available for the chassis functions. If the ignition is off and the auxiliary battery voltage should drop below 12.8 volts (voltage of a fully charged battery) for 4 seconds, the isolator relay will open, preventing the coach loads from discharging the main battery."
I'm am including a schematic of the Battery Control Center for reference. See attachment 2. Note the 'Bi-Directional Isolator Relay Delay Electronics' (BIRD) on the schematic. The components of the BIRD are on a PC board that is integrated into the Battery Control Center. Attachment 3 is a picture of the PC board. Note the 2 large connectors on the left side of the board and the row of fuses. That part of the PC board is visible in Attachment 1. The rest of the components of the PC board are under the relays.
Looking at the PC board it is obvious that the circuit is really simple. It does not use sophisticated electronics to achieve its function. Not much to go wrong.
I disconnected the extra relay and tested the function of the Battery Control Center. It functions as described in the quote from the Intellitec Battery Control Center Manual. I did not attempt to measure the delay times nor did I attempt to verify the low battery function defined in the Manual. But it does connect and disconnect the batteries from each other using the Isolator Relay at the appropriate times.
2003 34' Georgetown on W20 Workhorse Chassis. UltraRV power mods. Doug Thorley Headers and MagnaFlow 12589 mufflers. Front Sumo Springs, Rear P32 Sumo Springs, UltraRV Track Bar.
1998 Jeep Toad.