Poor-Man’s Smart-Grid

Ever hear of the “Smart-Grid”?

It’s a pretty cool idea – using advanced electronics and communications to control power to maximize the electrical grid and keep it up and running. One idea I keep hearing about is the idea of using electric cars as part of that system. Basically, electric cars get connected to the grid to charge them. If there’s a sudden increase in demand, power can be pulled from the electric car battery to provide the additional power.

It’s a neat concept but not without a lot of problems. Just to start with, there’s a lot of standardization that would be required between auto manufacturers, electric utilities, and third parties just to make everything connect and talk to each other. Beyond that, we already have trouble with currently failing infrastructure and government budgets. Who is going to foot the bill for the Smart-Grid, when we aren’t even keeping up our current grid?

I do like the concept of using an electric vehicle for something more than just transportation. Basically, it’s a battery bank on wheels. A while back, my cheap (made in China…) 48V compact charger for my electric motorcycle crapped out on me. It would be nice to get a more powerful, fully automatic charger, but without having to shell out the big bucks for one. After thinking about it for a bit, I realized that an Uninterruptible Power Supply (UPS) is a battery charger AND a power inverter, all in one case.

My buddy Tom recycles computer components by trade, so I asked him to keep an eye out for a recycled 48V UPS. Since my electric motorcycle is 48V, there’s no reason why I couldn’t use the UPS to charge my motorcycle, but also use it to take my garage OFF-GRID!

Sure enough, a few weeks later, I had a free UPS. It was dinged up and had no batteries, but the electronics worked perfectly. I set to work making a special cord to connect the UPS to the motorcycle, and also one to back-feed the UPS to the wall so that I could power my garage from my motorcycle!

I only needed a few hardware store electrical parts, and a few industrial components. Inside the UPS, the original plug to the batteries just used standard spade connectors. I chopped those off and instead crimped the wires to an Anderson connector – a popular industrial electrical disconnect. I then wired a matching connector directly to the 48V battery pack in the motorcycle, and fashioned an extension cord with the same connectors, so that I could park my cycle a few feet from the UPS.

Next, I wired up an additional, dedicated, 20-amp electric circuit, complete with a twist-lock electric outlet. That outlet is unlike anything else in my garage. By making a custom cable to go from the UPS to that outlet, I had a dedicated way to feed power from the UPS, back to the fuse box, and back out to the rest of the garage. I could even feed electricity back to my house if I wanted (although only at 120V, NOT 240V.)

The system works really well. It’s what I’ve been using to charge my electric motorcycle all summer.

A few weeks ago, we had a blackout. It was HOT outside (100+ degrees at night!) and we suddenly had no A/C, lights, or refrigeration. I flipped the house main breaker off (disconnecting us from the grid,)  went out to the garage, plugged in the cable, and turned on the UPS. Back in the house, all the circuits on the “A Leg” had power. Of course, those were circuits that I already planned on being the important ones in case of a power outage.

We had power to our fridge, our ceiling fan, kitchen and living room light, and the radio. While everyone else on our block was sweating it out, we had cold drinks, a nice cool fan, and news and entertainment!

Because I used salvaged equipment for the project, I only needed to pay for a few electrical connectors for the dedicated cabling. So I had not only an electric motorcycle charger, but a household power backup, all for $20 or so!

Have you cleverly repurposed something to take your place off the grid? Do you have great secondary uses for YOUR electric vehicle? Let us know!

For a more “Step-by-Step” version of this project, please take a look at the write-up I did for Instructables.com!

-Ben