Longer mash

I have a 12v cooler which will also keep items warm. I placed water in a jug in it. I checked the temp a few hours later and it was around 120*, by the next morning it had reached 153.9*.

If I heat a mash mixture like that, what would happens?

How much water was in the jug?

A full Sun Tea jar or about a gallon.

i guess the first question would be... is it safe to have un-contained liquid in there - meaning have you tried pouring the water right into the cooler and then testing temps that way.

doesn't sound like you have much control over it (just on or off) but sounds like it could certainly work if it's safe!

The cooler uses fans to move the air across a Peltier device in the cooler wall, so a separate container inside for the mash is needed. I do 3 gallon or smaller batches and I currently use an 8qt SS pot to mash in. I just checked and my pot fits inside the cooler.

I think some testing with a reading every 30 minutes should be my next step. Maybe preheated so the test starts at 120* or so. A controller to limit the upper temp might be needed.

I guess I need to look into recipes which require a highly fermentable wort.