I have a theory about parties held outdoors. Every one of them has a cord. It’s orange. It runs from a kitchen window or a garage or a generator, and it crosses the grass at the exact spot where a man holding two drinks is going to find it with his foot.

You know this man. You may be this man.

Blame the frozen margarita. In 1971, in Dallas, Mariano Martinez rigged a soft-serve ice cream machine to make them. That machine sits in the Smithsonian now, in the National Museum of American History, which tells you how seriously this country takes a cold drink. For fifty years since, the frozen margarita has been plugged into a wall.

A theory is no good until you test it. So this month I stood behind a table at the Chefs For Farmers Food & Wine Festival in Dallas. Shade. Black tablecloth. A bottle of Lunazul blanco, a stack of LiquidZERO frozen margarita mix pouches and a great deal of ice. And a blender with no cord.

It’s called the All Terrain Blender. Two quarts, red base, a 40-volt battery where the plug ought to be. Tom Lovering invented it, and he sent us one to try.

The plan was simple. Make margaritas until the crowd quit or the battery did. I had my money on the battery.

Here’s how it goes. Mix, water, tequila, ice, lid. Start slow, so the blades pull the ice down instead of throwing it at the lid. Bring it up. Hit Turbo. Listen. The rattle turns into a heavy, even roll, and that’s the sound of a drink being finished. Pour.

Then do it again. Two quarts, then two more. All afternoon. Hundreds of margaritas, a line of people holding out cups, and not one moment when the motor sagged or stalled or asked me for anything. The power came on as gently or as hard as I wanted. The jar took a festival’s worth of handling and never complained.

At the end of the day it was still running on the charge it showed up with. The crowd quit first.

Lovering is the president of All Terrain Appliances, Inc. He put a brushless motor and a bank of lithium-ion cells in that red base, and the company says it runs like a 1,200-watt plug-in machine and makes more than 500 margaritas on a charge. He holds two patents on it. A third is pending. I didn’t count to 500. But I was there, and I believe him.

The smart part comes after the party. The base slides inside the jar. The whole thing packs down to 10.5 inches tall and weighs less than seven pounds, which means it fits the standard 11-inch upper cabinet in an RV. It has a light for after dark. The battery will charge your phone and ten others.

It’s built for a sailboat, a campsite, a hunting lease. I’ve only had it on a festival lawn. That was enough.

It costs $385. That’s about $15 less than the closest Vitamix, and the Vitamix needs a wall. On Kickstarter it’s $285 right now, because the company’s VIP list takes $100 off. That’s real money for a blender. I’d pay it to never see the orange cord again.

So I’m revising my theory. Every party held outdoors has a cord, unless somebody brought this. Then it just has margaritas.