Call me old fashioned, but I started using the pour-over method for making coffee when my last coffee maker died. I can boil the water any way I like and then pour it over the coffee grounds using the same carafe and #4 filter as I used with the coffee maker. I’ve use this every day; last time we had a power outage I brought out the butane burner to boil the water and had coffee quicker than on the 220VAC stovetop burner.

That’s for making coffee. As for keeping coffee hot all day... who does that? Geez, if the coffee is so old you need a powered carafe to keep it hot you are taking too long. Make a fresh cup, your taste buds will thank you. This looks like a solution in search of a problem.