The way the system worked:
12 volts came from the Land Rover truck battery and was charged continuously by the alternator. it fed a 12 volt power inverter ( the 1000 w Black and Decker unit), plus the 12 volt water/glycol pump and 2 12 volt PIDs to monitor fermentation temps. But the power inverter also powered a 120 volt trickle charger which charged a deep cell Marine battery.
The idea here was during the day while we traveled, the Land Rover powered the demand for the pump and PID's, when we stopped for the night, I converted power from the deep cell to keep the pump running overnight and at stops. As the battery would run down over night, it was recharged during the day, it worked perfectly.
The control panel
The way the glycol system worked:
The pump circulated the liquid thru a cooler which had a stainless steel coil, ice was added and maintained a reasonable level of insulation and fairly low level of melting. The PID's where connected to thermocouples into the fermenters, a range was set ( I choose to ferment at 62-65 degrees) and as needed the PID's called for the pump to come on or not. I added a low level grant for adding glycol or purging air from the system. It took some time to prime the system but the grant helped and worked smoothly after it was all balanced and running.
The chilling circuit: