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Utilizing 12v DC Systems for Primary or Emergency Power

By: Tom Chatham

When the grid power that you depend on suddenly stops for an extended time, you need an alternative supply to work with. If you have an off grid home you will have the same options to look at for power. The main thing is if you are living off grid for extended periods you will need to analyze how you create and utilize that power.

Using a backup generator for a few days every year is a far cry from providing all of your power on a continuous basis. A backup generator is great but most of them are not built to provide power on a continuous basis. Even if you had the fuel supply to run it for a year it is likely your generator will break down after only a few hundred hours if you are even that lucky. I have seen a brand new generator suffer an electrical failure after the first hour of operation with no load on it. The motor had to have an electrical component replaced inside the motor which required a mechanic with the proper tools and the replacement part.

For those that want or need to live off the grid it is necessary to look at the power system and understand where the weak links are. If you find yourself in a situation where you must provide all of the maintenance and repairs yourself, you must have the necessary tools and repair parts as well as the knowledge to do the job. In a longterm situation, the simpler the system is the more reliable it will be and the less you will need to fix over time. There are systems that are well made if you can afford them, and they will give many years of service but eventually you will run into the same problem. You may be called on to repair them some day and most people are not prepared to do that.

If you are contemplating a retreat to shelter you from some kind of catastrophic event, you will want something that the average person can work on and maintain with minimal effort for thousands of hours. It is common to find that the most efficient and easy to use systems are filled with high tech components that the average person does not understand and has no hope of fixing given a component breakdown. The more electrical components you have in your power chain from the generator to the appliance you wish to run, the more chance you have for a failure of some type that requires replacement of a component or equipment to restore electrical power.

Living off grid you have three basic choices for electrical power. You can have no electrical power, use 110v AC or 12v DC. In many cases you will have a combination of AC and DC components. To keep things simple you may want to analyze your situation and determine if using only 12v DC power may be best longterm.

Utilizing only 12v systems will greatly simplify your system and make it easier for the average person to fix when something breaks. A pure 12v system works well with alternative power generation such as solar, wind and hydro. In most cases you are generating power and storing it in a battery bank for later use. If your appliance is 12v DC you will be able to run this item straight off the battery system . In this instance you have reduced your components to the very minimum. Generator, regulator, battery and appliance. This is basically how the electrical system on a car is set up.

This very basic electrical system is easy to maintain, very durable and easy to repair. An automotive alternator can operate for thousands of hours and can be rebuilt with a few tools and repair parts by anyone with some mechanical ability. The automotive regulator either internal or external is easy to replace and easy to stock extras for future use. There are many 12v DC appliances available that can be useful in an off grid household to include refrigerators and freezers.

When thinking of longterm use the fewer appliances you have the easier it will be to provide the power you need. Having only a few necessary appliances and some 12v lighting will allow you to harden your system and get the most out of it over time. With a 12v system you can still utilize 110v appliances when needed utilizing power inverters but in the event these components become inoperative you will still have the use of your 12v system for full utilization.

You may still need a motor to turn your alternator but you will have more options to do so. You can use a small air cool motor that you already have and if it breaks you have the ability to replace it with another one. You can even use your car to provide the power and use it to charge a battery pack. The ability to power engines with homemade fuel also allows you to generate power when fuel is hard to find.

Making automotive alternators the center of your power system will give you much more flexibility over time. It is much easier to find another alternator than an AC generator especially in desperate times when everyone is looking for them. The same can be said for power inverters. We have an AC generator for emergency use but to date it has not been used.

In the past when we have suffered power outages lasting for days we have used a home built system. We take the motor off of our rotor tiller and bolt it to a board with an automotive alternator. This system charges a set of deep cycle batteries. We then hook a power inverter to the battery pack to run the freezer. With this type of system we can run the motor only a few hours a day and have uninterrupted power all day and night. This helps to conserve limited fuel supplies and limit’s the wear and tear on the motor.

When the power goes out we take everything out of the kitchen freezer and put it in the deep freezer. We then place gallon jugs in the deep freezer to freeze and rotate these into the refrigerator to keep it cool. This allows us to keep everything refrigerated and only have to power one appliance to conserve on power.

Having some type of plan to maintain power to essential devices is essential to maintaining your quality of life when you can no longer depend on the power grid. Whether you use 12v exclusively or a combination of AC and DC power, you will need to have something you can depend on if the unthinkable happens and you are thrown back on your own resources.


Off Grid/Grid Down Power Systems: Part I

By: Tom Chatham

Whether you are thinking about moving off the grid or are concerned about a grid down scenario, the need for power production equipment can lead you in many directions depending on what you need. Many of the modern day conveniences we take for granted can be eliminated without causing serious deprivation but some things are beneficial to your standard of living. The need for refrigeration, water pumping and lighting are among those things that make life much easier if they can be done at the flick of a switch. While even these things can be performed with non-electric means with the proper planning, they free up time and energy for other things.

When planning for off grid/grid down operations you need to consider what your absolute needs are. While you may need power under both of these situations, the systems will have some subtle differences. The major difference will be the duration of grid down time. A short duration will require much less energy production capability in the form of liquid fuel storage.

For a short duration power failure you may only need alternative power for a few days. This will require less fuel reserves and less equipment overall. While a plan to deal with a long term power situation will work for short term situations the opposite is not true. A more robust and self sustaining system is needed for long term use. There are certain components you need to consider when building an energy system.

Energy source
Power production equipment
Energy storage
Power conditioning/conversion devices
Power usage devices

In a short term power situation you may opt to rely on a generator as many do. The generator will need a fuel supply that you must have on hand. The loss of power will prevent the purchase of fuel locally so this must be taken into account when this type of plan is devised. With a generator there are five negative aspects that must be taken into account. The generator must be used in a well ventilated place which opens up the possibility of it being stolen. A generator is noisy which will advertise the fact to your neighbors that you have resources they may not. A generator needs a constant supply of fuel that must be stored on site and last throughout the situation. A generator will only provide power while it is running. A generator has many electrical components that can fail at any time and prevent power production such as the coil, spark plug or control panel.

For a temporary power disruption these things might not present a problem but under prolonged disruptions, it could cause serious friction within your neighborhood unless you live in a remote location. The longer your neighbors have to live without power the more they may come to resent you for being prepared. It is for these reasons that alternate methods may serve you better.

With an engine of some sort to produce electrical power you will need a fuel source which could become a weak link in your plan over time. Unless you have the ability to produce the fuel you need, you may want to develop other options for prolonged use. The use of solar and wind present viable options for long term use while eliminating the need to store a fuel source. These systems can be the foundation of a multi platform production capability. The use of a power driven generator can provide good backup capability for this type of system, reducing the fuel needs of this type of device.

With a power generator there are six viable options for fuel. You can use gasoline, diesel, propane, natural gas, alcohol or wood gas. The use of natural gas and alcohol fuels are options but are not as readily available in many locations. Gasoline and diesel will require a large tank and the addition of fuel stabilizer for long term storage. Propane will store indefinitely but will also require a large supply on site. Wood gas can be used and the wood fuel produced from locally available sources. For long term viability, wood gas or alcohol would be the best options for local fuel production. Bio diesel produced from soybeans is also an option for self sufficiency. Information on alcohol and bio diesel production can be found in Brown’s alcohol motor fuel cookbook.

With a solar or wind system you eliminate many of the negative features of a power generator. These systems are quiet, non polluting, require no stored fuel supply and have minimal parts that can fail making them very durable. These devices charge a battery bank that can supply power even when the devices are not producing any power providing the ability of uninterrupted power for limited uses. With a battery pack you also need a power inverter to convert the 12v DC power into 120v AC power that household appliances can use.

One way to get around the expense of a power generator is to build your own. If you are using a battery pack for energy storage it may be more efficient to use a homemade generator to charge it. By combining a 3 hp motor with a car alternator, you can produce 12v power and charge your batteries. Depending on how much power you require you may be able to run your motor just 2 or 3 hours a day and have uninterrupted power around the clock. This could make the necessity of storing fuel much easier.

Where you might need 5 to 8 gallons of fuel a day for a typical generator, a homemade unit charging a battery pack may only consume ½ gallon a day. A typical alternator produces around 1,000 watts of power so producing and storing 2 or 3 KWH of power in a few hours is possible. A large deep cycle battery can hold about 1 KWH of power. A typical refrigerator/freezer or small deep freezer will use about 1.1 to 1.3 KWH of power a day so an hour and a half of run time can power your freezer for 24 hrs. The advantages of this type of system quickly become apparent. Even if you only have the homemade generator, inverter and several batteries, you could have continuous power for almost 2 weeks on the fuel needed by a conventional generator in one day.