2 Pack RV Holding Tank Heater Pad

I installed two heating pads as Lithium ion battery heaters. The batteries have low temperature cutoff control. So they will shut down and protect themselves during very low temperatures. That's what saved them from these heating pads. I was controlling the pads through a separate, adjustable electronic thermostat. I left the original snap action limit switches that are factory wired to the pads ( the only temperature control method that comes with the pads) inline just as a backup safety incase the electronic thermostat had any issues and wouldn't shut off. That was a big mistake!Both switches for their respective pads refused to close and energize the pads. The batteries were down to 14f when I checked on them today. Even thought the digital thermostat had closed and was providing good 12 volt nominal power to the input wiring of the pads, including directly to the pad limit switch. Once I removed the switches and wired passed them, the pads energized and started to warm the battery bank. I checked continuity of both switches and even though they had just been removed from 14f battery cases and were sitting in 3f air temperature, they were both open. I would not recommend this manufacture if they can't provide and test reliable control systems for their equipment. If my batteries didn't have a working low temperature cutoff built into them, I could have lost an expensive bank of batteries by using these.