There are two types of electric "Coolers" one is the ThermoElectric solid state (Think Koolatron) units, I call them a -30 box because the best they can do is 30 degrees below "Room" temp so if it's 100 in the shade, they get you to 70, if it's below 70 they work. (70-30 = 40 which is the warmest you want a fridge)
The other is a high effiency compressor unit, these are way heavier, I know both Dometic and Norcold have offerings in this category, I do not know if Coleman does, they usually run on either 12vdc or 120vac draw around 35-40 watts running and the Engel next to me does a great job of keeping ice cream frozen even when it's 90+ here in the RV.