Gratz, I think. Do you have a TM-2025?
I would love to know the DC amps they pull.
Apparently they make both kinds. Here is what the manufacturer has to say about the products.
Q) When should the UltraHeatŪ Tank Heaters be turned "ON"?
When should it be turned "OFF"?
A) The 13.5 VDC power switch for the 13.5 VDC UltraHeatŪ Tank Heaters should be turned "ON" or the power cord for the 120 VAC UltraHeatŪ Tank Heaters should be plugged in when the outside temperature approaches freezing 32°F (0°C.) The 13.5 VDC power switch should be turned "OFF" and the power cords unplugged when the outside temperature stays above freezing. All UltraHeatŪ Tank Heaters are thermostatically controlled, they turn "ON" automatically when the holding tank temperature is 44° F (7° C) and turns "OFF" automatically when the liquid in the holding tank reaches 64°F (18°C.) The UltraHeatŪ Tank Heater should be turned "OFF" or unplugged when dumping the holding tank.
Another update: They also make a dual powered pad. (120VAC and 13.4VDC) not sure how you select which one to use. Also the 12VDC units pull 10 amps when running (PER PAD) and I have 2 in my unit. The units with a galley tank have 4 pads (one on the galley elbow).
With nothing else on but the tank heaters, my 75 AMP HOUR (as delivered) DC-24 battery would last about 3 hours. Add the furnace and it would not make two hours.
Not an issue while towing for you though since the pads would draw power from the TV. I will need to check this further. Been over a year since I looked at my tank heater paperwork.
Lou and Laura with Bella - German Short Hair Pointer
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