Elementary Electricity
Copyright © March 19, 2025 by Robert Wayne Atkins, P.E.
All Rights Reserved.
Introduction
There are two basic types of electricity;
- AC or Alternating Current: This is the type of electricity that is delivered to your home. It provides power to your refrigerator, lights, and appliances (microwave oven, coffee maker, and fans).
- DC or Direct Current: This type of electricity operates a battery-powered device, such as a handheld flashlight, a cell phone, a tablet (or iPad), a laptop computer (when the computer is not plugged into an outlet), and a motor vehicle (a 12-volt battery generates the initial spark that ignites the fuel in the engine and then the vehicle's 12-volt alternator takes over).
AC Power
In the USA there are two major types of AC electricity:
- 110 or 115 or 120 volts:: These are not different types of electricity. These are all the same type of electricity. Appliances that use this type of electricity may refer to this type of electricity using any of these three numbers (110, 115, or 120 volts). This is the voltage that is used by most refrigerators, washing machines, lights, fans (ceiling and portable), portable electric space heaters, and some window air-conditioners.
This type of electrical wiring normally has three different wires as follows:
- Hot Wire: This wire will usually be black or red.
- Neutral Wire: This wire will usually be white or gray.
- Ground Wire: This will usually be a green wire or a bare wire. However, some small appliances do not have a ground wire.
- 220 or 230 or 240 volts: This type of electricity may be referred as 220 or 230 or 240 but it is the same type of electricity. Typical appliances that use this type of electricity are electric clothes dryers, electric ovens, and central electric heating and air-conditioning systems.
DC Power
DC power is battery power. There are many different types of batteries and they have different volts and amps.
All DC systems have a positive terminal and a negative terminal. The electricity always flows from the positive terminal to the negative terminal.
12-Volt Batteries for Motor Vehicles:
- Positive Terminal (+): A 12-volt automotive battery has a PLUS terminal and the red wire from the engine connects to this terminal.
- Negative Terminal (-): A 12-volt automotive battery has a MINUS terminal and the black wire from the engine connects to this terminal.
There are two major types of 12-volt batteries:
- Normal or Automotive: These batteries are designed to provide a significant amount of power to start an engine. Then the battery is recharged up to its maximum potential.
- Deep Cycle or Marine or Golf Cart: These batteries are designed to provide continuous power over an extended period of time. When the battery has been discharged to its minimum power (usually 9.5 to 10.5 volts) then the battery needs to be recharged to its safe maximum power (usually 12.5 to 13.3 volts).
Flashlight Batteries:
Flashlight batteries have a positive (+) terminal at one end of the battery and this end of the battery usually has a slightly raised metal end. The negative (-) terminal is at the other end of the battery and it is usually flat.
The most common sizes of flashlight batteries are AAA, AA, C, and D. However, very few devices are currently being made that use the C or D size batteries. Most devices now use either the AAA or the AA size battery.
All of these batteries are advertised as being 1.5 volts. However, the bigger batteries have more amps.
Flashlight batteries are available as follows:
- Single Use: The battery can be used until it has been drained of all of its power and then it should be discarded. This type of battery cannot be safely recharged.
- Rechargeable: The battery can be recharged hundreds of times until it will no longer hold a charge. Then the battery must be discarded.
Rechargeable Device Batteries:
These are the batteries that are inside cell phones, tablets, portable computers, and a variety of other devices. Most of these rechargeable batteries can be recharged by plugging a special AC adapter into a 110-volt wall outlet, or by plugging a special DC adapter into the recharging port (cigarette lighter plug) in a motor vehicle. The AC adapter and the DC adapter are both designed to convert the incoming power into the correct DC voltage required by the device. Most of these batteries have a life expectancy of several years if they are properly maintained.
Reserve Electrical Power
In the early 1900s electricity was considered to be a luxury item. Many families that lived in rural areas did not have any type of electricity. For example, my grandparents on both sides of my family did not have any electricity on the small farms on which they lived.
In the 21st century electricity has become essential to the survival of most people all around the world. Although most people could survive for a few days without electricity, most people in the 21st century would not be able to survive if there was no electricity for two weeks or longer.
In the 21st century most people worldwide have become dependent on water and electricity being delivered to their homes. If the water or the electricity stopped flowing to their homes then a lot of people would start dying for a lot of different reasons.
The good news is that most people could collect enough rainwater each time it rains in their area to meet all of their water needs (until the next time it rains). However, they would need a few heavy-duty tarps and enough water storage containers to store the water until the next time that it rains.
Electricity is different. When most people think about providing their own electricity they usually think about buying a generator that runs on gasoline, or diesel, or propane, or natural gas. A generator will run for between 2 to 2.5 hours on one gallon of fuel. And the generator must be running for it to produce electricity. When the generator is on then you can use a little electricity, or an average amount of electricity, or a lot of electricity. But there is no way to store the surplus electricity if you do not need it when the generator is running. On the other hand, the utility company that provides power to your home will allow you to use no electricity, a little electricity, or a lot of electricity at any time and you only have to pay for the amount of electricity that you use. This is the major difference between a utility company and a home generator. The cost to operate a home generator is the same regardless of how much of the generator's peak power you need at any moment in time. If you will stop and think about this for a few minutes then you may realize that a home generator may not be a reasonable option for your specific situation.
On the other hand, a small solar generator may be just right for you. A solar generator requires a monocrystalline solar panel (100 watts), a charge controller, a 12-volt deep-cycle battery, and a pure sine wave inverter (at least 2000 watts). The entire system can be purchased for less than $300 (March 2025). And the entire system can be connected together using red wires (positive) and black wires (negative). And a solar system does not make any noise and it does not create any carbon monoxide. And the entire system can be easily moved to any spot that gets good sun. If the sun hits different windows in your home at different times during the day then you could move the system to the window that is getting good sun. And you could store the sun's energy as electricity inside your 12-volt battery. When you needed electricity you could use the 12-volt battery to provide DC power. Or you could use the 12-volt battery to provide 110-volt AC power using an inverter. It is also possible for the 12-volt battery to provide DC and AC power at the same time. A small solar system would not provide enough 110-volt electricity to run a refrigerator for more than 30 minutes. A small solar system would not provide 220-volt power to operate a well pump. But a small solar system could be used to recharge the batteries in your cell phones, tablets, and portable computers. And it could be used to run several small fans to keep you cool during a hot summer day when the sun is making you very uncomfortable. The small solar system could also recharge all your AAA, AA, C, and D rechargeable batteries so that your flashlights and your worldband radio would always work. If you will stop and think about this for a few minutes then you may realize that a small solar system may be a reasonable and affordable option for your specific situation.
For most families, the cost of a solar power system that would be big enough to provide all the electricity they need to keep their entire home operational would not be feasible for two reasons.
- Cost: The total cost of the entire system would be excessive and it could not be economically justified using a twenty-year payback period.
- Reliability: A solar system will only recharge its battery bank when the sun is shinning. If you have several days of bad weather, or significant cloud cover, then the batteries will discharge and you will run out of electricity.
However, as mentioned above, a small solar system that is strategically used to provide electricity to a few critical devices could significantly enhance your chances of survival during a long-term grid-down situation.
Conclusion
Depending on your situation, you may not need any type of electrical power to survive if the electrical grid goes down in your area for an extended period of time.
On the other hand, if you had access to a small amount of renewable electric power each day that the sun does shine, then that small amount of electrical power could make a significant difference in your ability to survive during a long-term grid-down situation.
If you are considering a solar system then you should invest in a monocrystalline solar panel that provides at least 100 watts of power when the sun is shining. Some solar panels have a charge controller that is already attached to the solar panel and the charge controller will prevent the overcharging of a 12-volt battery.
Some additional information about solar power is on my website at the following link:
A Very Simple Explanation of a Backup Emergency Power System
Respectfully,
Grandpappy.
Grandpappy's e-mail address is: RobertWayneAtkins@hotmail.com