More than once, I’ve been very grateful for our generator. When the power goes out and it won’t be coming back online for many hours or longer, a generator is one purchase that is worth every penny. But how do you know which type and size to buy? Here’s what you should know before making that expensive purchase.
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In this article
Electricity is critical to our lives. More than ever, our civilization relies on electrical power for everything: lighting, entertainment, communications, security, heating/cooling, cooking, food refrigeration, the list goes on and on.
Short power outages (under 12 hours) have resulted in widespread traffic chaos, hospital evacuations, and even civil disorder. Multi-day outages can adversely affect water and sewage systems, supermarkets, gas stations, and cellular phone systems.
This subject is huge and I am only scratching the surface here. As a result, I’m not discussing solar, wind, or small-hydroelectric power. All three have pros and cons that are discussed at length in print and online. Here, I will concentrate on what most people can easily put together in a suburban environment with a reasonable investment in time and money.
Generate and Store for Extended Power Outages
Preparing for extended power outages is a little more complicated than you’d think. These days, having a generator is just scratching the surface…EVERYTHING in our lives consumes electricity. While you could run a generator 24 hours a day, it is a horribly inefficient waste of fuel, as well as a surefire way to piss off your neighbors and attract unwanted attention.
Any serious power outage strategy will also include one or more storage batteries, a 12-volt-to-120-volt inverter, and a quality battery charger. You can run your generator in the daytime to power appliances and charge batteries, then shut it down overnight while you quietly run your devices on the stored power in your batteries.
The Basics
The electricity that comes out of your wall sockets is 120 volts, alternating current (AC). AC current is easy to transmit long distances but cannot be stored. It is very dangerous if mishandled, resulting in burns, electrocution, and/or death. Conversely, direct current (DC), which is used in phones, laptops, and car batteries, can be safely and easily stored for later use. A 12-volt DC current is one of the keys to emergency power.
Electrical Definitions
Let’s define a few electrical terms:
- Current: This parameter is measured in Volts; think about a mountain stream, the higher the current number, the stronger the current, and the more power is transmitted through the current. This is a measure of force, or “push.”
- Amperes (Amps): This is a measure of the quantity of electricity. We’re most familiar with amps because an overload of amps on an electrical circuit usually causes a fuse to blow or a circuit breaker to trip. You know, Mom using her blow dryer while Susie heats up her coffee in the microwave…too much power in use. Batteries are rated in terms of “Amp-hours,” which is an expression of how long the battery can provide a certain quantity of power.
- Watts: This is the measure of the amount of work that can be done. It is the key to determining if appliances can be accommodated in a given electrical circuit. It is a familiar measure for light bulbs and blow dryers. More importantly, it is the measure used to rate the power-generating capacity of portable generators and inverters.
AC current can be converted to DC current; we do this every day when we plug in our phone or laptop charger. DC can be converted to AC through the use of an “inverter.” To store power, we use “deep-cycle” batteries, which look like car batteries but are specifically designed to efficiently take in and give back DC current. When we need an AC current to run a refrigerator or lights, our inverter converts the DC current to AC.
Determining What You Need
Like generators, inverters are rated in watts so you can easily choose the model for your needs. Deep-cycle batteries (also called RV or Marine) are rated in amp-hours; using the formulas below, you can calculate the size and number of batteries to support your system.
If you can understand a couple of basic formulas, you are set: Watts=Volts x Amps, and Amps=Watts/Volts. All electrical devices are marked with their power requirements, allowing you to make an electricity “budget” and intelligently plan for your needs. For example, my refrigerator requires 5.0 to 6.5 amps when operating. Using the equation above we can determine the number of watts it needs: 6.5 x 120 volts= 780 watts. Here are some common wattage requirements for various appliances:
- Table lamp: 40-100 watts
- Toaster: 800 watts
- Microwave oven: 1500-2000 watts
- George Foreman grill: 800 watts
- Electric skillet: 900 watts
- Cellular phone charger: 24 watts
- Laptop AC adapter: 72-144 watts
- 42” Plasma TV: 286 watts
- Digital cable box: 40 watts
If I expected to run all of the above devices at the same time, I would need to provide up to 5,100 watts of electricity. However, if I planned ahead and was careful not to use high-wattage devices at the same time, I could get away with only half of that capacity. As you might expect, the more watts you need, the more it will cost.
Building a System
So let’s build a simple system based on the above information, assuming that we will run the generator 12 hours a day (7:00 AM to 7:00 PM), and use inverter-provided power the other 12 hours. If we do all of our cooking while the generator is on, we can get along with a smaller inverter and less battery capacity for our nighttime needs. We can also freeze some ice blocks during the day, putting them in the refrigerator compartment at night and turning the fridge and freezer controls down to low at night; if the fridge stays closed, it will run minimally at night.
Our system will include a 3,500-watt-rated generator ($400), a 1,600-watt inverter ($110), two Sears Diehard Marine batteries with 180 amp-hours capacity ($220), and a Diehard automatic battery charger ($75). This solid, basic system can be upgraded as needed and will maintain your ability to communicate, cook, store food, and stay alert for emergency notifications. Don’t forget to sock away enough extension cords to reach your appliances.
Also recommended is a small power bank to keep indoors and move from room to room as needed.
Your electrical preparedness strategy is crucial to your family’s safety and comfort in a disaster. The good news is that you don’t need to be an engineer or electrician to properly prepare for when the lights go out.
READ MORE: If a power outage happens in cold weather, you’ll want ways to stay warm that will help you conserve your stored power. This article has ideas for that.
Gasoline vs. Propane
The two most common fuels important to people preparing for emergencies are gasoline, which is liquid at room temperature, and propane, which is used as a gas at room temperature.
While most consumer generators are available only with gasoline engines, in the last few years there has been an increase in the availability of generators fueled by propane, or propane and gasoline (usually called “Dual-Fuel”). This is very important for the home generator user for these reasons:
- Gasoline is difficult to store safely in sufficient quantities to keep a generator running;
- You may already have propane as fuel for your BBQ grill or patio heater;
- Propane tanks are very safe to store at home, and tank exchanges don’t require power; and
- Having the ability to use different fuels in a disaster situation is priceless.
Propane, also known as LPG (Liquefied Propane Gas) is used for heating and cooking in mostly rural areas where natural gas is not available and is stored in large tanks at the user’s home or business. Periodically, the propane tank is refilled by a mobile propane truck.
Advantages of Propane
Propane has the advantage of portability, available in consumer-sized portable containers including the popular 20 lb. tank used for barbecue grills and a small 16 ounce tank used for lanterns and small barbecues.
Another advantage of using propane is that it is a cleaner-burning fuel than gasoline, and so the exhaust is less of a health hazard if you’re working around it while running.
Using Propane
Using propane with a generator can be tricky at first, as I learned with my first dual-fuel unit. I hooked everything properly and while the generator worked great with gasoline, I couldn’t get it going on propane. Fortunately, the manufacturer was nearby, and the service guy who helped me showed how to slowly open the propane valve to avoid activating a leak-prevention safety device. Once I had that figured out, I was good to go.
Other Fuel Options
Diesel & White Gas
Other liquid fuels include diesel fuel, a denser, oily fuel popular in trucks and generators, and “white gas,” a petroleum fuel related to gasoline but used in the popular Coleman and other brand camping stoves and lanterns. Unlike pressurized gas fuels, petroleum liquid fuels have a limited shelf life; they separate into their component chemicals over time and become unusable.
Natural Gas
While natural gas has more widespread use in home heating and cooking, it is used less in rural areas because of the extensive piping needed to distribute it. Where it is available, it is cheaper and easier to use than propane. Natural gas is lighter than air, and thus disperses more easily than propane which is heavier than air.
“Inverter” Generators
Another relatively recent trend is the introduction of the “Inverter” generator, which can be confusing in the context of this article. As I described separately, a 12 volt to 120-volt Inverter can be used as part of a quiet energy storage and retrieval system for overnight use, for a freezer, for example.
An Inverter Generator creates “cleaner” AC power better suited for electronics like computers, and if you need to run a desktop computer directly plugged in to the generator it may be worth the price premium ($100-$300) you’ll pay for one. However, most appliances and battery chargers work just fine with a conventional generator, and since a laptop’s power supply charges its’ DC battery, there’s no problem running it there as well.
Solar Generators
A solar generator might be the best choice for you as a backup power supply. They’re silent, never give off any dangerous fumes, and there’s no need to store fuel. Survival Mom has tested and uses these solar generators from 4Patriots. Read this post for a thorough review of 4Patriots solar generators.
Generator Safety
Portable generators are invaluable during power outages, but they can also be dangerous if not used correctly. Here are some essential safety tips:
Frequently Asked Questions
They both have advantages and disadvantages. A solar generator stores energy for later use, being charged by an electric outlet or solar panels. It’s completely silent, which is very nice since other generator types can be extremely loud. Survival Mom has a short class to learn more about all types of generators and decide if you even need one! You can get all the details for that class at this link.
That’s a great question! Here are a few suggestions. Before you need it, think about where you could store it so the distance between the generator and the hook-up point is as close as possible. (Be sure you know where and how to hook it up!) If you must move it, prepare a smooth pathway from Point A to Point B. You could place the generator on a platform truck like this one and keep it there year-round. Make sure it can easily hold the weight of your generator. Finally, ask for help! A generator is heavy, must be hooked-up correctly, may need to be refueled in the duration of the power outage, and then should have some maintenance done each year. This could be a job for a handyman/woman if hiring someone is the best solution.
Not surprisingly, the best container to store gasoline is called a “Safety Can.” These 5-gallon cans are built to prevent rupture, and have a spring-loaded seal instead of a screw-on cap. The seal keeps the gasoline vapors securely inside, and a spark arrestor screen prevents the contents from igniting from a flash back. In the event of a fire outside of the Safety Can, the seal will vent gasoline vapor that builds up inside, preventing a catastrophic explosion.
A Type I Safety Can is just for storage, you’ll need a funnel to pour out the gasoline. It’s also the least expensive of the Safety Cans, available on eBay for about $40.00 each. Type II Safety Cans add a flexible spout to make refueling easier, and are about $60.00 each. Reputable brands include Justrite and Eagle.
If you decide to store gasoline or diesel, you have to plan a rotation schedule, as they both will start to decompose within several months. Using old fuel in an engine will cause major problems in short order. You can extend their life with a fuel stabilizer like STA-BIL, but ultimately if you don’t use it you’ll lose it.
Let’s say you store 8 five-gallon cans of gasoline, for a total of 40 gallons. Number the cans 1 through 8, and each week empty one of the cans into your car or other gasoline-powered equipment and refill the can. Mark this on a calendar and it becomes automatic; in two months, you’ve rotated your gasoline stock without too much trouble.
Related Power Generation & Storage Content
- Two Ways to Quietly Run a Chest Freezer During a Power Outage
- Is a Solar Power Source the Right Backup for You?
- Buying Tips for Your First Generator
- Which Emergency Light Sources are Best for Your Family?
Thanks for this info. I’ve been looking at an alternative to running the generator when we don’t need to worry about running our sump pumps. I’ve been wondering about inverters and this really helps give a direction to look into.
THANK YOU for this stripped down, info filled article!
I have found many articles on this topic, but all are written for the electricity educated and/or MIT graduate!
With this information, I can EASILY get what I now know I need to sustain me through an electrical outage….
GREAT stuff!
A couple of things to consider when building such a system:
1. If you can afford it, I’d suggest a pure sine wave inverter rated to support a power surge of around 2200 Watts (the start-up surge on a refrigerator’s compressor can be about triple the appliance’s running Watts). Some appliances (like anything motor-driven) run less-efficiently on modified sine wave power.
2. Don’t forget that the batteries in such a system will need to be maintained. Battery University is an excellent resource for learning about the care and feeding of batteries (it’s recommended on a solar power forum on which I participate).
Thanks, your input is valued. Rather than invest in a pure sine inverter, I was thinking about investing the difference in inverter cost in a UPS instead? I only need the pure sine for computer things, so would it work out better financially to pay for a UPS and get the additional battery storage from it and rely on the UPS to deliver the clean electricity to the computer?
What you call current is actually called voltage. Current is what you call “amps”. Just to be clear.
One significant correction: Although you correctly state the basic equation, “Current” is measured in Amperes, and the other quantity, “Potential,” is the one measured in Volts. You can think of the voltage as the potential speed, or pressure, and the amperage as the amount of electricity available to flow. This is WHY the relationship (volts times amps equals watts) works.
Consider: if you had a job (work) to do such as using water to clean some gunk off a dinner plate, you could either pour many gallons of water over the dirty plate at a sluggish speed of a couple of miles per hour, OR you could squirt only a few onces of water at the plate at 100 miles per hour… both methods would yield a clean plate, although the first is a lot of water at low speed and the second is a tiny bit of water at high speed. 1 Volt at 100 Amps equals 100 Watts, and so does 100 Volts at 1 Amp… or 200 Volts at half an Amp, for that matter… all three are 100 Watts, the SAME amount of work. You can think of Voltage as the speed, Amperage as the amount of water available, and Wattage as the work done.
Another point: the description you used for deep-cycle batteries actually applies to ALL batteries (geek note: yes, yes, many batteries are manufactured already charged, but the acid or alkaline paste still had to “take in electrical energy” at some point whether the means were chemical or electrical). The salient point for deep cycle batteries is that they are still manufactured with the thicker lead plates that all car batteries had prior to about 1965, and thus can be drained most of the way down to zero charge and still re-charged again and again… up to a thousand times, according to the labels, whereas a typical modern car battery, with its very thin (read: cheaper) plates can only survive a very few such nearly-complete drains of charge.
One other minor matter: if you use a Mercury-vapor fluorescent (ugh) or much safer LED bulb in your table lamp instead of incandescent, the figure drops down to the 6 to 14 Watt range… not a minor consideration when designing a backup power system.
I hope this helps.
AC current is very dangerous if mishandled, resulting in burns, electrocution, and/or death. Conversely, direct current (DC) which is used in phone, laptop and car batteries is able to be safely and easily stored for later use.
It’s not the whether electricity is AC or DC that makes it dangerous. If anything, DC is more dangerous than AC because of inductive effects (the tendency of flowing current to want to keep flowing). What makes electricity dangerous is its voltage along with its maximum current capability. Twelve systems are safe (AC or DC); 120 volt systems can kill you (AC or DC).
Interesting concept. I would definitely go with a high quality pure sine wave inverter to avoid destroying your sensitive electronics. Also, more importantly, two 12 volt 180 amp-hour batteries will not provide as much power as you think. These batteries are rated to provide 180 amps at 12 volts for one hour or a total output of 2 x 180 x 12 = 4.3 KiloWatt-Hours (KWH). However, I don’t recommend totally draining those batteries each night. They won’t last that long. Perhaps 50% usage is more reasonable. In this case you will only have 2.15 KWH available for 12 hours of night. So, on average during the night, you can only use 2.15 KWH / 12H = 180 watts. I think that a very important aspect of emergency power is to use devices with extremely low power consumption. Don’t use incandescent bulbs. Just three 60 Watt bulbs will use up all your available nighttime power. Think LED for lighting. Only use low power electronics, not a 42″ plasma TV. Also, the George Foreman grill and electric skillet will drain those batteries very quickly and leave you with no power. Other low tech methods will be much better for cooking such as a gas grill or a camp stove with propane bottles. You can store more energy in propane than you can in batteries.
Good article except for one thing…Current is not measured in Volts, Voltage is. Current is the flow of electrons through a conductor and it is measured in Amperes, or Amps. Voltage is the actual ‘pushing’ force that you referenced while, as you stated, Current is what actually ‘makes things happen’. (synopsis version)
The start up amps needed are called locked rotor amps, and can be difficult to find out, fridges & air conditioners can get pretty high.
Good introductory article. It’s nice to see a starter system available for under $1,000. I agree with AuricTech that the start up amps of a compressor (refrigerator) is about triple the running amps. Also, you might be interested to know that electrocution is a fatal exposure to electricity. An “electric shock” is a non-fatal exposure to electricity (so saying electrocution and/or death is redundant).
Current is measured in amps (Amperes), not volts. Voltage is measured in volts.
Comparing electricity flowing through a wire to water flowing through a hose, voltage is equivalent to the water pressure inside the hose, and current is equivalent to the volume of water (gallons/min) flowing through the hose.
It’s great that you’ve thought all this through!
One important thing to remember is that there are many ways we can reduce our electricity needs. When you need new appliances, buy energy efficient models; it will save you money in the long run, and lower your energy needs in an emergency situation. Maintain your appliances, too; the user manual should cover that. (And keep the manuals accessible for future reference!) Cleaning the coils on your fridge is easy and makes a big difference, but how many people do it?
And switching to LED bulbs can be great! Not only do they use a fraction of the electricity, but they last many times longer. The initial cost is more, though – maybe a lot more. Definitely pays to shop around!
Under Building a System: It sure would be nice to have links to the ‘simple system’ items:
3,500-watt-rated generator
1,600-watt inverter
Diehard Marine batteries with 180 amp-hours capacity
Diehard automatic battery charger
Otherwise, great post!
Generator safety should be expanded: news items have linked touching generators with death…….