Backup Power Overview

The Key to Selecting that Off-Grid Backup Generator

We live in interesting times to say the very least. From war to plague, the modern world seems (at least, in my opinion) to be on the brink of some even crazier times. I would be lying if I wrote that I wasn’t already preparing for this years ago. I started prepping back in 2008 because I thought that within just a few short years I would be defending myself against hordes of zombies, condemned to living out my days alone in a world with no future. That day never came. Instead, the world kept going, people kept living and eventually, we ended up with the troubled times of today.

Now, the mess we have today hasn’t produced the zombies I thought would be roaming the streets, but they are out there in one form or another. Furthermore, you don’t have to prepare for the same event(s) for which I am prepping in order to have an interest in backup power. There are always the natural and man-caused disasters around the world, such as hurricanse, sunamis, earthquakes, and tornados to give any reasonable person pause to consider how one may mitigate a long-term disruption to the power grid. Whatever the cause, such an event has the potential to drastically change how one lives daily life. Therefore, whatever preparations can be made in advance of such an event can help to improve life in the aftermath.

Such an event is often referred to as a shtf event, or stuff hitting the fan event. When preparing for this, I prioritize backup power because I like electricity. Electricity makes life easier and more convenient and I have a lot of electronic devices I want to use if things go sideways. I want to power my refrigerator and freezer so my food doesn’t defrost or spoil and I want to make coffee. Having unspoiled food and coffee to drink can make all the difference to a person’s state of mind during a shtf event and that is priceless.

Before building or buying a generator, it is crucial to consider the amount of daily energy consumption of the appliances or electronics you wish to power. If your generator is too small, then it won’t produce enough power. Plain and simple. I measured the energy consumption of my appliances with this meter. You can use any meter to measure, but just be sure to do it. I cannot stress this point enough. Being realistic will save you the time and frustration of having to deal with the shortcomings of any system that you decide to purchase or build. If you find that you simply cannot power everything you want to power, then at least you know and can plan ahead. In my situation, I know I cannot provide power for everything I want to power. So, I have prioritized my devices and I have figured out ahead of time through testing of my generators that I can use certain devices one at a time, instead of simultaneously. For instance, I can provide electricity to my refrigerator around the clock for months using my larger 24V solar generator, but the second I want to plug my washing mashing into my generator the refrigerator must be unplugged. The surge power from both appliances running at the same time is too much for the inverter and the protection circuit shuts everything down. Testing the system over a period of months led to this discovery. I wanted to know the extent of the capabilities of all my generators in addition to being familiar with how to use them, so I tested them all months. I put them through all kinds of tests, which is beyond the scope of this article.

Later in this article, I will focus on my smaller 12 volt generator. This particular generator powers the lights for my indoor Kratky vegetable grow boxes. That’s where I currently have celery and lettuce growing. I wrote an article focussing on this grow method and you can find that article here. Before I get further into the details of this diy 12 volt generator, I want to discuss some other options for backup power. These options are ones I have considered myself. I looked at purchasing several different types such as PTO, gas and completed solar generators. I’ll cover these now.

PTO Generators

Depending on individual circumstances a PTO Generator may be something to consider as a source of backup power. PTO stands for Power Take Off and this type of generator uses another power source, like a combustion engine, to transfer mechanical energy into electricity. The drive shaft of a tractor connects to this generator to provide the mechanical rotation this generator needs.

They come in various different sizes which can be mounted onto a portable cart or trailer to be moved to a desired location. The relative portability of this type of generator is one of its benefits. It can also supply enough power to keep larger appliances on. If a diesel tractor is used with it, then diesel fuel will be needed but diesel is safer to store in large quantities than unleaded gasoline. The drawback to using this type of generator is that it requires another source of power, such as a tractor. The external engine of a tractor is loud and can draw potentially unwanted attention to your location. The footprint of this system is larger and it cannot be brought indoors, which would require additional precautions to prevent carbon monoxide poisoning.

Gas Generators

Consumer grade gas generators are handy when a source of electricity is unavailable or difficult to access because they are relatively small and portable. They also don’t require a separate source of power because the engine is built into the design. This is appealing to those of us who do not own tractors. The principle of the generator is still the same though, converting mechanical energy to electrical energy. An inverter provides alternating current (also known as AC) through a number of outlets, which vary by type. Modern versions may include USB ports whereas older ones will not. These generators can be loaded onto a vehicle or carried by hand to a location around a property with relative ease.

Various makes, models, and capacities are widely available due to their mass production over several decades making them common. Their their replacement parts are also common. Like any other engine, they require regular maintainence and care. Some gas generators can even be converted to operate on propane instead of unleaded gasoline. Operating on propane is cheaper and safer.

There are cons to using a gas-powered generator during a sthf event. First, gas generators are noisy. When the grid goes down and you’re running a gas generator, your neighbors are going to hear it running. As soon as they do, they will know you have gas and electricity. So, if you live in the suburb of a major metropolitan area with neighbors living fifteen feet away or less, you might want to rethink any plans to run a gas generator. Otherwise, you may hear them knocking on your door or worse. If you live out in a rural area, the noise can still attract unwanted visitors roaming around the area, looking for a farmhouse to raid. Take precautions by clearing a good field of fire, setting up an early warning alert system, and blocking any paths on ingress.

Second, a gas generator requires gasoline. In a shtf event, unleaded gas will become scarce and extremely expensive. You will want to plan ahead for this if you plan to use this type of generator. How will you refill the generator once it runs out of gas? Do you plan to store gas ahead of time? If so, then how? Will you steal or buy gas from others? If so, then do you plan to siphon it? Do you own a siphon? Unleaded gas is more dangerous to store than diesel fuel, so if you’re planning to store it, make sure to take the proper precautions.

These generators also produce exhaust. The exhaust is dangerous. Without proper ventilation to prevent carbon monoxide poisoning, this type of generator cannot and should not be used indoors. It must remain outside in order to be operated safely.

Solar Generators

Solar generators are becoming more popular and common. There’s a variety of brands manufacturing them and like gas and PTO generators, solar generators come in all kinds of sizes and capabilities. The features built into the inverter depend on the model, which range in price, but include USB charging ports, 12V sockets, and AC outlets. Some even come with built in and attached solar panels.

Unlike their gas powered counterparts, solar generators use a battery bank to supply power. The batteries can be recharged using a chord that plugs into a standard AC outlet or with external solar panels. A built in solar charge controller regulates the charge coming in from any solar panels being used. The battery chemistry of the internal batteries varies by manufacturer but many are commonly lithium iron phosphate (LiFePo4), which offer an advantage over other types of lithium batteries. A battery management system (BMS) to monitor the current flowing in and out of the batteries is also built into these generators.

Overall, this type of generator is appealing because it is easy to use, lightweight and portable, and it doesn’t produce a lot of noise while in use. Compared to running a PTO or gas generator, the solar generator is quiet. It can be safely used indoors and it doesn’t require the use of gas, propane or diesel. There are some cons to using this type of generator though. First, the batteries in the generator have to be recharged. If other sources of electricity are scarce or unavailable, then this generator must be connected to one or more solar panels to recharge the battery bank. Solar panels only work during the day and even then, their efficiency can vary depending on cloud cover and the angle of elevation towards the sun. Careful consideration must be given to how much voltage and current the charge controller can handle. Too much current or voltage from one or more solar panels can result in damaging the controller, or worse, it can cause a fire.

The second con to using this type of generator has to do with the type of battery used in the battery bank. A LiFePo4 battery or battery bank consisting of that kind of battery isn’t a bad thing. These types of batteries are relatively safe, as their chemisrty is structurally stable. They can be exposed to harsh conditions, the battery cells are incombustible and if they happen to catch fire, thermal runaway is unlikely. So, why is the battery type a disadvantage? When selecting a solar generator, it is important to research the battery technology and battery chemistry of the battery inside the generator. Lithium Ion batteries made with other cathode materials, such as cobalt-oxide, can be dangerous. When these batteries are exposed to harsh environments or they are damaged, they can explode. A poor battery management system can also allow these batteries to over or under charge, creating unstable charging conditions which can also cause a fire or explosion. Fires involving these types of batteries are extremely difficult to extinguish, as water and traditional firefighting methods do not work. Special chemicals have to be used and fire departments often do not have them on hand. So, when other types of lithium ion batteries catch fire, they are usually just left to burn themselves out. Be sure to research not only the battery chemistry but also the quality of the battery management system, when selecting a solar generator to purchase.

The third and final drawback to this type of generator I will mention is that third party solar generators can’t really be worked on. If something inside breaks, it becomes useless. Think about the context of s stuff hitting the fan scenario. If the solar generator you’re using suddenly stops working, will you know how to repair it? These generators are completely enclosed in a plastic housing (usually) that has to be carefully removed. Inside the housing are the batteries, battery management system, solar charge controller and other electrical components? Are you confident that you have the skills to repair or replace something that has stopped working? Will there be a functioning supply chain to get you the replacement parts?

Repair or Replacement Discusion

The supply chain question applies to all types of generators. So does the ability to repair or replace broken or damaged components. Someone with mechanincal skills may be able to work on a gas generator to keep it going but that same person may not have the electrical background needed to diagnose and fix a problem with a solar generator. However, regardless of one’s skillset, if a functional supply chain doesn’t exist, then obtaining replacement parts to keep any generator going will be impossible. That’s why supply chains and manufacturing ability is important. Currently, most Americans have access to most of the components needed to keep any of these types of generators running. If you decide to purchase one, it would be a good idea to research common problems others have had and then buy the spare parts that would be needed should you encounter the same problem.

My 12 Volt Generator

Weighing the various options, I chose the solar generator for my source of back up power because it is better to have a quiet generator in my current living environment. I have a total of three solar generators ranging in size and configurations. The first one was also a do-it-yourself project involving the help and expertise of my dad. He designed a system that was a hybrid between two different blueprints, one from Will Prowse and another from a local ham operator, who’s identity I do not have permission to share at this time. The companents are mounted to a piece of ply-wood and that mounted to a hand-cart for mobility. It’s a 24V system and is the largest of the three. Perhaps, I will write it up separately in the future.

The Second one I own is quite small. It’s the Ecoflow River Mini. I purchased this to power smaller electronics. I can take this with me when traveling to charge my phones, tablets, or to run small fans or whatever. You can find it here on Amazon. I have comepletely discharged and recharged it using only solar panels several times. It will also charge of off a standard AC outlet in my house. I can’t use it to power major appliance like my 24V system but it is handy.

The third, is my small 12 volt generator which was built to fit inside a milk crate. All of the components except for the battery fit inside of this space. The battery sits on the floor next to the crate and connects via fused battery cables. The design for this generator was based on the design developed by Will Prowse, author of “Mobile Solar Power Made Easy!” His book walks the reader through everything. He covers a lot of material including how to select a battery. His website mobile-solarpower.com also has a wealth of information as does his Youtube channel WillProwse. The resources he provides will really help you to dive deep into the topic of mobile solar power.

Many of the components I purchased for my system were recommended by Will. As you can see in the picture above, it all fits into a crate and that makes the footprint of this generator small. Some drilling was needed in order to mount the components. The benefit to building a system like this is that you gain an understanding of how it works and therefore, if something breaks or stops working you know how to replace it. It is also relatively easy to work on this sytem. Each component is easy to get to.

If you are interested in building a generator like this, I have no objection to copying this desgin. Simply figure out first how much power you need, like I discussed at the begining of this article and then purchase what is needed. The next step is figuring out how to fit everything into the crate and where it will mount. Screws, bolts, washers and nuts will be required along with some tools.

Please note: I am not a certified electrician and I am not responsible for any injuries incurred by anyone building their own solar generator. Consult a certified electrician if you have questions. Working with electiricty is dangerous and can result in serious injury or death. Take proper care and use caution when working with electricity.

Component List

Given the availability of each component on Amazon, I chose that website to purchase the components. I labeled the components in the above picture for the ease of listing them out. I’ll hyperling the name of each component.

A. Battery Disconnect Switch - This shuts off the current between the battery and the rest of the system, allowing for work on either the battery or other components.

B. Solar Charge Controller - This works with a variety of batteries and solar panels. It regulates the current into the system from the solar panels.

C. 100 Amp Shunt - This is used with the multimeter (H) to measure the current from the battery.

D. Circuit Breaker - This shuts off current between the charge controller and the rest of the system.

E. Positive Power Distribution Block - This accepts and distributes all of the power from the positive terminals of each component.

F, Negative Powever Distribution Block - This accepts all of the ground wires for each component.

G. Remote Meter for Solar Charge Controller - The MT50 remote meter can be purchased separately if needed. The link I included for the solar charge controller had one included. I recommend having one either way because it will display the current and voltage coming in from the solar panels.

H. Multimeter - The multimeter displays information about the current coming from the battery through the shunt. This particular meter comes with a shunt and I have linked them both so you can find them with either link. There are better multimeters out there. I will tell you that this particular meter is basic and it gives a ballpark figure regarding how much power is left in the battery. A it is possible to use a more advanced meter with more features, but this is the one I decided to use. Additional meters can be added to the system for additional readings too.

I. Push Button Switch - This switch is wired to a resistor that is under the switch. The resistor is necessary to charge the capacitors in the inverter, prior to turning on the system. Will Prowse explains why this is important here. The resistor to use can be found here.

J. Custom Housing - Ok, let me explain this. The top of this was fabricated out of separate pieces of clear acrylic plastic, which were bonded together with adhesive and then it was all attached with screws to the top of wood. The housing hides the wires under the meters and covers the resistor needed to charge the capacitors in the inverter. It also hides the chord for the remote switch for the inverter. It was needed so that the meters and the button could be mounted in such a way to make them accessible and visible. This was a personal preference over mounting these components directly to the sides of the crate. Sometimes custom a build sparks creativity and that creativity is expressed through the fabrication of something new that meets a need.

Caption 1: A partial view of the wires hidden under the Custom Housing.

Caption 2: A closer look at the outside of the Custom Housing.

K. Remote Switch - This button powers on the inverter remotely.

L. Power Inverter - This 12 Volt Pure sine wave inverter provides the electricity I need to keep the lights on over my indoor vegetables. This is the component that delivers the goods to the electronics requiring power.

M. ANL Fuse - This 100 amp fuse protects my inverter. If there is a sudden surge of current into this part of the sytem, the fuse will blow and my inverter will be safe.

N. Circuit Breaker - This circuit breaker allows for the current to be shut off between the charge controller and the solar panels. In order to safely connect and disconnect solar panels to the system, this breaker needs to be in place and shut off.

Lastly, the milk crate I used is this one. Be sure to match all of the power ratings for each component before purchasing and assembling anything. Refer back to the Will Prowse videos for other ideas and to learn more about how to build these systems. Remember, I’m running two Spider Farmer SF1000 LED Grow Lights with my generator. Those can be found here. I wanted a way to grow food indoors and off-grid during seasons of extreme weather and in case the grid goes down. Instead, I just ended up powering my lights all the time on this sysem.

It has taken some testing and experimentation in order to figure out how long I can run the lights and for how long. I have connected solar panels to the system in series, parallel and series parallel in order to figure out what works best. I’ve found that the positioning of the solar panels relative to the position of the sun also matters. There are a lot of factors to consider and since the Earth’s rotation is always changing, the best orientation of the panels has been a challenge to determine.

What About My Battery?

As of today, I have only one 12 volt LiFePo4 battery in the system. After watching Will Prowse completely dismantle a Weize battery and run rigorous tests on it, I decided to go with the brand. Overall, this is one of the best batteries on the market. I own several of them and so far, I am satisfied with their performance. The 100AH 12V Weize Battery can be found here as well.

Conclusion

This diy project was not too complicated nor was it too difficult to build. However, building a solar generator from scratch is not for everyone. If you’re looking for something complete then just be sure to research the various models on the market. No matter which kind of backup generator you get, remember to be realistic about your needs. Figure out how much daily power you will require and find a generator that meets those requirements. Then prioritize which electronics you need to power and when the stuff hits the fan, you’ll be ready to execute your plan.

If, on the other hand, you want to build your own solar generator, then I hope this article gives you some ideas and resources about how to go about doing it. I should mention that these mobile solar systems can be used in RVs, for traveling, and for camping. You don’t have to be a prepper to want backup power or mobile power. Either way, no matter which backup generator you go with, you won’t be left in the dark!

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