I own both a 13 and a 19 quart and don't have any issues with keeping them alive. With my 13, I purchased 4 dozen big emerald shiners during a walleye tournament. Bought them on Thursday and left the 13 in the back of my truck during the evening. They were still alive on Sunday.

Last week, in the 90 plus degree heat, I purchased 5 dozen minnows and put them in my 19 qrt. At the end of the day, I had two dead minnows and I think they were DOA to begin with.

It may help you to add some ice cubes to your water when storing them at home. We usually use a fish tank bubbler at home just to ensure the batteries don't run out in the middle of the night.

I suggest cleaning your minnow net (that fits in the box) as well as the box itself. For me, when I empty my minnows, I pull the net and hang it on the side to air dry. I also allow my box to air dry. I do NOT leave the lid closed or a wet net inside of the box. This "might" be a culprit.