Dude and I have been talking about this for a while. I finally got around to giving it a try. Part of this was sparked by some of Dude's suggestions, and part of it was from a brainstorm I had when I caught a glance inside one of those travel coolers that runs on car cigarette lighter power. It turns out that they're nothing more than Peltier coolers, and they contain many of the parts required to adapt the same principle to a fermenter. Here are some pictures and further explanation:
Here you can see some of the inner workings. I sandwiched a second 40mm/113W Peltier device (eBay) between a 1/2" aluminum plate and the guts of the travel cooler. The devices work as heat pumps if you stack them on top of each other (with sufficient power and heat sink capability). The threaded aluminum bar is intended to extend inside the keg (like an aquarium cooler) and seals with an o-ring.
Here's another view with the threaded piece attached. You can see how one of the Peltier devices is sandwiched between the aluminum pieces. The other one is insulated with a foam square from the travel cooler.
Here's what it looks like inside the keg:
Here's a picture of my first test run. It's plugged into a 12VDC/6A power supply. The keg is a 7 gallon corny I welded up today. I'm monitoring the temperature with the digital thermometer on top. It'll probably be a few hours before I notice any temperature changes.
Here you can see some of the inner workings. I sandwiched a second 40mm/113W Peltier device (eBay) between a 1/2" aluminum plate and the guts of the travel cooler. The devices work as heat pumps if you stack them on top of each other (with sufficient power and heat sink capability). The threaded aluminum bar is intended to extend inside the keg (like an aquarium cooler) and seals with an o-ring.
Here's another view with the threaded piece attached. You can see how one of the Peltier devices is sandwiched between the aluminum pieces. The other one is insulated with a foam square from the travel cooler.
Here's what it looks like inside the keg:
Here's a picture of my first test run. It's plugged into a 12VDC/6A power supply. The keg is a 7 gallon corny I welded up today. I'm monitoring the temperature with the digital thermometer on top. It'll probably be a few hours before I notice any temperature changes.