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DIY Solar Powered Window Air Conditioner: Part 4, Upgrade to 48v/Smoke Test

Let’s make some upgrades to the Solar Peltier System. Since starting this project, I’ve learned a lot about planning power budgets, how power supplies generate heat, how amperage at lower voltages can turn into a lot of heat, and how heat moves in an air conditioner. I’ve pulled the unit out of the window and started some upgrades that definitely keep things cooler. Keeping the power supply and lines cooler means more energy is available to power the Peltier modules and actively cool the room. I’m starting to understand why so many of the Peltier projects I see online fail — they’re probably introducing more heat to the room than they save. The all 12v system generates an unsafe amount of heat in the wiring, so let’s get that voltage up and decrease the amperage going through the wires!
48v @ 6A is much nicer than 12v @ 24A! At 12v, the wires were easily 140F (60C) or more, and I’m not interested in living to the ripe old age of “died in a house fire.”
Upgrades
So here’s a pretty simple laundry list of my current upgrades:
- 48v 400W power supply, this should also stay cooler, since it will be running at lower power than it’s full rating. The previous supply was right up (and even above) it’s actual rating, which probably was causing some of the extra waste heat.
- Soldered connectors and screw-down connections. Tighter connections to reduce waste heat.
- Peltiers in series directly tied to 48v supply, other 12v systems from a separate 48v to 12v converter.
- Inline Fuse for Peltiers After running the smoke test (below), I realized I really need some kind of fuse for the 48v@6A Peltiers. 15A was the lowest I had, but that should at least prevent some kind of runaway if something goes wrong.
- Wire nut connections for any temporary connections. Tighter connections to reduce waste heat.
- All power supplies go outside. Did this on the previous build as well. At some point I’m gonna move the fan below the power supplies, as I’m sure the extra heat load isn’t helping.