I made a baitwell using a Marine Metal Fish Saver and a 36-quart Igloo Marine Ultra Cooler. Works great. I wired the fish saver to a 12V plug so I can easily plug it into either of my 2 12V receptacles on my boat. I tie the cooler down with a bungee to the captains seat which keeps it held solid while under way. Only modification I made to the cooler was to cut a small "V" out of the lip under the lid so the power cord for the fish saver fits nicely. I use it for minnows and bluegill. I also have a 120V aerator I use at the house to keep oxygen levels up while waiting to go fishing. I've kept minnows alive for over 2 weeks in it by changing 1/3 or so of the water every few days and keeping the temperature down with frozen water bottles as needed. I bought a cheap digital aquarium thermometer off of Amazon to keep an eye on the water temperature. It should work fine in a 100-quart cooler as well since it is rated for up to 30 gallons. I have it dialed down pretty low when using it in my 36-quart cooler. Turned all the way up it would probably quickly beat my bait to death.
https://www.amazon.com/gp/product/B000EYUJFS?psc=1&redirect=true&ref_=oh_aui_detailpage_o08_s00
https://www.amazon.com/HDE-Digital-Fish-Aquarium-Thermometer/dp/B00GR0LKN8/ref=sr_1_3?ie=UTF8&qid=1456931316&sr=8-3&keywords=digital+aquarium+thermometer
Only picture I have of my setup, but you should get the idea.