Don't think it really matters what you put them in when it's cooler outside. I have used a standard ice chest and the Engel bait keeper. When the temperature gets up into the 90s I add a little ice to the water throughout the day in both. The Engel bait keeper does keep the water temp down longer when it's really hot but still have to add ice occasionally in either one. The main thing I like about the Engel is I can latch the lid and not loose half my water going to the lake or while I'm running across the lake in rough water. It's nice to keep your boat floor dry when the temperature is in the low 30s outside. Nothing worse than paying for a pound or 2 off minnows and loosing all your water and bait on the way to the lake.