If you can get a small 25 watt bulb.. You might have one in you refrigerator... Also you can leave the top of the cooler partially open to vent some of the heat..
The idea is to use the smallest heat source you can.. You want it to struggle to keep your desired temp.. That way there is no chance of over heating..
The idea is to use the smallest heat source you can.. You want it to struggle to keep your desired temp.. That way there is no chance of over heating..