Introduction: Poor-Mans Smart-Grid - Blackout Protection by UPS and Electric Motorcycle
First Prize in the
Off the Grid Contest
I came up with the concept of the "Poor-Man's Smart Grid"
Read on to discover how I not only got a great new charger, but can power my detached garage or even my entire house in a blackout, directly from my electric vehicle.
But first, what IS the "Smart-Grid"?
Please keep in mind that this project involves both both AC AND DC power, at potentially LETHAL voltages.
Persons unqualified and uncomfortable with household electrical should keep their hands out of the fusebox, and hire a professional to instal a backup generator system for them.
Electrical Code varies from one place to another. I make no claim on meeting code in your area.
Back-feeding power out to the grid during a blackout is illegal and highly dangerous. Any backup system must make use of "anti-islanding" technology. Connection to the grid MUST be disabled when running backup power.
Step 1: Smart-Grid Concept
The Smart-Grid requires smart, bi-directional meters, and electronic components that can either charge an electric vehicle OR pull power from it as needed.
At night, an electric vehicle owner charges their vehicle from wall power. At any time that the grid has sudden demand (or a sudden drop in supply) electric power is instead PULLED from the vehicle's battery pack to meet that demand. Electric vehicle owners will be compensated through special electricity pricing for being part of the program. A great deal of infrastructure is required for the Smart-Grid, as well as standardization between vehicle manufacturers, utilities, and interconnected equipment.
The way I see it, the Smart-Grid is a great CONCEPT, but has a number of issues. For example, what if I can't drive as far as I need to in my electric car, because my neighbor was simply being extra-wasteful with his energy use? How much money will it take to set up the Smart-Grid, when we have continually shrinking budgets in government, and much infrastructure that is already behind on repairs and maintenance?
On the other hand, what about a PERSONAL Smart-Grid? A small-scale concept of the Smart-Grid could be designed using little more than hardware-store parts and salvaged materials.
For my project, I required:
- An Uninterruptible Power Supply (UPS)
- Power cables and connectors (typical hardware store components)
- An electric vehicle - in this case, my electric motorcycle
Step 2: UPS - More Than Just a Delivery Service
At the heart of this system is an uninterruptible power supply, or UPS.
You may have a UPS on your home or work computer. It's typically a box that you plug into the wall, and then you plug your computer into it. In case of a power outage, the UPS instantly kicks over to battery power, giving you some certain small amount of time to continue using your computer, or at least save your work, and shut down the system. When power comes back on, the UPS recharges the 12V battery inside it, so that it's ready for the next time it's needed.
So, a UPS is actually TWO things. It's both a DC to AC Power Inverter (typically converting 12VDC to 120VAC) AND it's a battery charger (usually low power 12VDC.)
So, when I needed a new charger for my motorcycle, could I just use a UPS? And if so, could I use it as a power inverter as well? The answer in both cases is YES!
I called up my buddy Tom, who happens to run a computer recycling company. I asked him if he ever gets any 48V UPS to recycle. He said yes, but that the batteries are always dead, that's why people throw them out. Of course I already had the batteries - in my electric motorcycle.
I asked Tom to keep an eye out for me. Sure enough, in a few weeks, I got a call, and headed over to his shop to collect a rack-mount 2200-watt, 48V UPS which would have been used in a computer server room. There were no batteries with it, and it had several dents and missing screws, but the electronics functioned properly.
By powering the UPS on wall-power, I could charge my 48V electric motorcycle, and by running it from the motorcycle, I could create AC power to take my detached garage, or even my house, OFF-GRID!
Keep in mind that not all UPSs are the same. Cheap ones only create "Square-Wave" AC power, which doesn't work well for battery chargers, computers, and electric motors. Higher quality UPSs, and specifically ones sold for use with computers create a very smooth AC sine-wave. In fact, we hooked up this UPS to Tom's osiliscope and found that it made better AC power than he got in his wall outlets from the power utility!
Step 3: Custom Cable - UPS to Wall
I would need several special connectors and power cables to make my "Poor-Man's Smart-Grid" work.
The first one wasn't special at all. The UPS already came with a standard 120V electric cord to plug into the wall.
Typically, there are several outlets in the back of the UPS to which you would directly plug in devices such as computers and monitors that you would want to keep running in a blackout. On the back of this UPS, there are several 15 amp and 20 amp circuits.
But I didn't want to just plug in a device or two. I wanted to plug in MY ENTIRE GARAGE and maybe even my house when needed. To do that, I would need to make my own "Load-Side Connection".
Alternating Current (AC electricity) changes the direction it flows MANY times per second. In the United States, it's 60 Hertz. That means that AC goes BOTH directions! If you think about it, doesn't that mean that an electric outlet could just as easily be an electric "inlet"? Sure can! All that is needed is a special cable to connect the UPS back TO a wall outlet.
I added an additional, dedicated, 20-amp circuit to my circuit breaker box. The only thing on that circuit is a single twist-lock electric outlet, now being used as an "inlet". I chose that particular style of outlet because is is common enough to be purchased from a typical home-improvement store, yet I don't have any other outlets like that anywhere else on the property. It's a unique and dedicated connection.
I purchased 6' of heavy power cable, a twist-lock male connector, and a 20-amp male connector, which features a turned blade when compared to a typical power plug.
Stripping the jacket and individual conductors of the power wires, I made a dedicated male-to-male power cord that would connect the 20 amp outlet on the back of the UPS to the 30-amp twist-lock electric outlet on the wall.
When not in use, the cable is unplugged from both ends, rolled up, and stored away.
Step 4: Custom Cable - to Electric Vehicle
Most electric vehicles are just a big battery bank on wheels.
Also, they are parked 90% of the time. Lets say you have a long commute, and drive to and from work one hour each direction. That's two hours you use your vehicle, and 22 hours per day that it's just parked somewhere.
While my electric motorcycle is parked it can recharge, OR be a battery backup for my garage and home.
The motorcycle has four 12V AGM batteries rated at 55AH each, or 2.64KWH of theoretical energy. This is a relatively SMALL battery compared to most electric cars or solar battery arrays, but it's still plenty for my use, especially since I use CFL and LED lighting, and efficient appliances and electronics.
On the UPS end, I needed to adapt the original computer-style power connector that went to the four batteries to an Anderson connector. I cut off the original battery spade connectors and crimped the wires in to an Anderson connector.
Next, I built an "Anderson Extension Cord" with two of the same connectors (making sure to maintain polarity) and a length of 6 gauge power cable left over from another project. I plugged in the short UPS to Anderson pigtail into the UPS, and then the extension cable into that. When not in use, the extension cable is coiled up and hangs on the back of the equipment rack.
To connect the motorcycle to the UPS, I added an Anderson connector to the the ends of the batteries in the motorcycle. The plug is accessible, by pulling it up out of the gas tank through the gas filler port.
With the cycle parked near the UPS, I plug the extension cord from the UPS to the motorcycle. I then plug in the UPS to wall power, and it automatically starts charging.
Step 5: Manually Switching Power
Here's what I do:
- Unplug wall power from UPS
- Plug in the cable from the UPS to the twist-lock load-side "inlet"
- Turn the main breaker OFF
- Turn the load-side "inlet" UPS DISCONNECT breaker to ON
- Power the UPS to ON
If I wanted to run power to the house, I would need to first turn off the main breaker in the house, then I would go through the same sequence, only leaving on the garage main breaker, allowing it to feed back to the house.
(If for some reason the UPS was "plugged into itself" by accidentally connecting it both to AND from the fuse box, the GFI will trip, breaking the circuit, preventing any damage to the UPS or creating an unsafe condition.)
Step 6: Real-world Application
So, what's a REAL-WORLD application that would make the POOR-MAN'S SMART-GRID useful?
I'll give you an example.
This summer, we had a terrible heat wave. Everyone on our block was using their central air-conditioning, which is a very heavy electrical load. My wife has a heat sensitivity, and can get physically ill from being too hot, so staying cool in a heat wave is that much more important.
It was still over 100 degrees F. in the evening, when the neighborhood transformer blew.
In the house, I turned the main breaker off to disconnect us from the grid*. In the garage, I plugged in the UPS backup cable and turned on the UPS, but did not turn off the main breaker back to the house. That way, the garage simply fed AC power back to the house and any other circuits on the same 120V "leg" of household power.
In the United States, typical home electric power has TWO 120V wires coming into it. Each one goes to every other circuit in the house. High power electric circuits, such as for an electric stove, are on a double breaker, which combines both 120V "legs" to give you 240V.
Since my UPS is only 120V, and on a single circuit, it only powers EVERY OTHER circuit in the house. Knowing that, all the IMPORTANT circuits are on that leg.
During the blackout, the refrigerator, kitchen light, living room ceiling fan, kitchen electric outlet, furnace (for winter blackouts), and water pump, were all on power backup.
We had cold drinks, running water, the ceiling fan and box fan running, electric light, and the radio for both news and entertainment, all thanks to the POOR-MAN'S SMART-GRID!
*Please note: as with ANY kind of backup power system you MUST be disconnected from the grid during blackout using any type of generator or battery backup, whether that's with an automatic disconnect or manual system.
Step 7: What's Next?
The POOR-MAN'S SMART-GRID has been a great experiment, which has expanded the usefulness of my electric vehicles and made my home more functional at nearly no additional cost.
But what would it take to make this setup even better?
Here's a few ideas:
Solar power is a great way to create electricity from a renewable source of energy, but the right amount of solar panels seldom fit on an electric vehicle! Typically, you are better off with them permanently mounted in your yard or roof of your house or garage. (Here's an exception, that I built as a solar-powered vehicle for my daughter - Solar Power Wheels.)
If you have solar panels on your garage, they can be connected to a solar charge controller, and a battery bank. Since 48V is a "standard" DC voltage common to solar equipment, solar panels can be routed to DIRECTLY charge a 48V electric motorcycle.
A solar charge controller like the Xantrex C-40 can run 12,24, or 48V systems. Instead of using it as a typical charge controller, it can also be set to use as a DIVERSION controller. When fully charged, instead of disconnecting power between the solar panels and electric vehicle, it would simply RE-ROUTE power to a different load. If the secondary load was a small Grid-Tie inverter, the excess solar energy would be routed to the grid (or deduct from the amount of energy my home is using) instead of simply being wasted.
While my system works well, it is not AUTOMATED.
A typical power backup system would use an Automatic Transfer Switch. An ATS is usually installed between the power utility and the home main breaker box. It is a "break-before-make" switch that automatically disconnects grid-power during a blackout, and then connects power to the backup generator.
On my system, a typical ATS wouldn't work, due to having a detached garage with separate breaker panel. However, the system could be automated through some clever use of relays and automated breakers, such as what's used in Recreational Vehicle power systems. At that point, I could simply always leave the UPS running and connected, and allow the automated equipment to kick over to backup power during a blackout.
I already have some solar panels, charge controller, a small grid-tie inverter, and some RV parts around. It would only be a matter of a little more work and study to automate the system.
Electricity is a wonderful thing. It can light up our living room, heat our home, cook our food, and transport us from one place to another. It's hard to imagine living without it. Because of so much of what we do is based on electricity, it's nice to have a backup plan and learn all one can about batteries, generators, and electrical power.
Please visit 300MPG.org for all my clean transportation projects or click HERE for my other Instructables.
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