I don't exactly know how to word this for a subject,
I have a lifepo4 battery I'm trying to keep warm enough to safely charge (via solar) this winter. It lives in a box that has an elevated aluminum (1/4" thick) floor and the battery sits atop that, separated by a thin silicone liner. The underside of the false floor features a 12v silicone heater stuck to the aluminum, which distributes the heat nicely.
I'm reading the temperature with the thermistor built in to the heat pad (these are for 3d printing) and I can hold whatever temp I want with PID, so that's great. But the floor temperature isn't really what I'm trying to control - more so the average of the two probes (on the battery monitoring system) which are several inches above.
Apologies for being long winded, but how would one go about targeting the average of the probe temperatures, while not making the floor a million degrees? I want the probe average to be like 47F, and the floor to be as hot as it needs to be to maintain 47F, without exceeding say 105*F. I could do some if-checkery but I feel like it'll result in the system just bouncing between writing off and on, negating the whole PID thing
Thanks for any direction