A lot of amateurs want to go off grid.
The demand and desire to take amateur radio off grid is absolutely there. The problem is that information about off grid radio is sprinkled around. It’s hard to find straight answers. Many radio and survival blogs occasionally address the issue, but to my knowledge, Off Grid Ham and OH8STN are the only two outlets that deal with off grid radio radio exclusively.
For readers who are not off the grid, or seek to expand off grid capabilities, I’ve put together this “off grid radio guide” for beginners that will answer the most common questions in one compact package. This is not a comprehensive guide; we’re just going to summarize main points. At the end of this article there will be links to additional information on the topics covered here.
Have a purpose!
Graphic courtesy of tunein.com
I’ve beaten this drum so much it may seem tiresome, but it cannot be overstated that having clearly defined goals is an absolute must. If you do not have a specific purpose in mind, then you’re just going to trip around randomly trying different things with no meaningful result. If you have the time and money to spend on dead-end projects, then by all means don’t bother with a roadmap; you’ll eventually find your way and probably have a great time doing it. Off grid radio guide
But for those of us who do not have the means to live like plans don’t matter, the first chapter in our off grid radio guide is to have a purpose. Your stated goal does not have to be complicated or lengthy. Here are a few examples:
- Operate for a weekend or so while camping.
- Helping kids/scouts/youth group with an educational project.
- Involvement with contests and SOTA/POTA activities.
- Energy independence/operate off grid full time from a home station.
- Survivalist/prepper communications for when SHTF.
- Curiosity/self improvement. Off grid radio guide
Your goals may change over time. I originally got into off grid ham radio just to experiment and fool around with solar panels. That lead to a large home station, several portable power setups, and this blog! Regardless of what your motivations are, make sure you can define them.
How much power will you need? Off grid radio guide
Answering this question is a major component of defining your purposes and goals.. After all, it doesn’t make sense to plan a power system without knowing how much power you’ll need.
If your plans include an engine-driven mechanical generator, choose one that will run at 33-50% of its maximum capacity while powering your equipment. This is the window where generators are the most efficient. You don’t want to push a generator close to its limit for extended periods, nor do you want a generator that is way oversized for the load it powers. Either of these two extremes are a bad idea.
Batteries.
Matching power needs to batteries is a very tricky dance because a battery’s performance can change with age, temperature, previous use, and physical condition. A handy rule to follow is that whatever number you come up with for your needed battery capacity, increase it by 50%. This will give you plenty of wiggle room for inherent factors that degrade battery capability.
When determining battery size, carefully consider the expected duty cycle you’ll be demanding of your equipment. Duty cycle is a ratio, expressed as a percentage, of transmit time to receive time. The more you transmit, the higher the duty cycle and the more battery you’ll need. At a minimum, figure a duty cycle of 25% and up to 80% if you run a lot of data.
Solar panel calculation.
No off grid radio guide would be worthwhile without discussing solar panels. The biggest variable is the sun itself. On a cloudy day, you may realize only 10% of your panel’s capacity. A solar panel will never hit its rated maximum power due to the varying levels of sunlight and the inefficiency of the system. Like batteries, include generous headroom in the form of more solar wattage capacity to make up for the losses.
“Headroom” also means having enough extra battery to power your gear for an extended time without a recharge. How long that time should be is up to you. Don’t forget to take into account charging time for the battery. For example, if you operate at night and have a depleted battery by morning, a bright sunny day is great to see, but it’s not the end of your trouble. You’ll still be off the air until your battery charges back up unless you have enough solar to run your equipment and charge the battery at the same time.
QRP vs. QRO.
Many arguments have started over whether high or low transmit power is “better”. The debate is elevated when the limited electric generating capacity that naturally goes with going off the grid is factored in. Setting aside these arguments for a moment, it’s worth noting that basing your station on QRP lets you scale down your electric generating system. You won’t need as much solar or battery. You can use a smaller solar controller, smaller gauge wire…smaller everything. Additionally, your budget can be smaller too.
I can’t decide for others the value of a high power (QRO) over a low power (QRP) off grid radio station. I can tell you that as someone who has separate QRP and QRO off grid stations, the QRP is the one I use and enjoy the most. The lowered transmit power is not as serious a drawback as one might think. Ask yourself: Is the hassle and expense (which are significant) worth extra transmit watts that will give you only a modest benefit?
Solar controllers. off grid radio guide
There are two basic types of solar controllers: Maximum Power Point Tracking (MPPT) and Pulse Width Modulation (PWM). Of the two, MPPT is more efficient, but it’s also more expensive. For smaller systems, MPPT does not deliver enough bang to make them worth the buck. PWM controllers are far less expensive and deliver good performance for the money. Solar panels 25 watts or less generally do not require any charge controller (this further reinforces the merits of running QRP). If you are undecided what to get, go with the PWM. Off grid radio guide
What else do you need to know? off grid radio guide
Going off grid with amateur radio is not nearly as complicated as it may appear. Although it can initially be intimidating and everyone seems to have an opinion, once you take a breath and jump in you’ll be surprised at how easy and fun it can be. I feel like there is almost too much information out there, leading newcomers to feel a little overwhelmed. Hopefully this short, all-on-one-page guide will put newcomers at ease and give them the confidence to move forward.
Resources.
These previous Off Grid Ham articles provide some insight about planning and focus:
A Mall Ninja’s Guide To Ham Radio Training.
The Future of Ham Radio Is Not In The Numbers.
Party Time Over; Get Working On Your Goals.
These Previous Off Grid Ham articles give additional information about calculating battery capacity and power needs:
What You Need To Know About Lithium Batteries.
Solar Panel Efficiency, part 1
Solar Panel Efficiency, part 2
A Radio Amateur’s Guide To Solar Panels.
Taking Care Of Your Storage Batteries.
What You Need To Know About Inverter Generators.
How Much Battery Do You Really Need? –This is one of the most popular OGH articles and includes a discussion of duty cycle.
Flooded Batteries For Off Grid Radio.
These Off Grid Ham articles discuss QRP and QRO:
The Travel Light Off Grid Radio Challenge.
Here’s an article about PWM and MPPT solar controllers:
What You Need To Know About PWM and MPPT Solar Charge Controllers.
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This article was very timely. It reminded me that I really need to do something with my QRP setup if I want to ever lug it along when I’m on the bicycle, which was my original goal. The setup I have now works great to haul around in the car; the 818, mag-loop antenna are light and take up very little room. It’s the laptop and the AGM motorcycle battery that are the issue now. I could run for a couple of hours off the equipment’s internal batteries, but I still need a way to top the batteries up. And I’d like to have a transceiver that is completely independent from the grid as well. And a power system I can switch over to use with our VHF/UHF gear we use for ARES. I’ve been doing some calculations and scrounging around places like Bioenno Power. I don’t like to plug specific companies but they have some really nice equipment. I’ve been looking at their solar charge controllers and other stuff and I suspect I may end up just buying everything from them even though they’re not the cheapest out there. I also need to look into a different computer. The old Lenovo works great but it’s too bulky and heavy to deal with in a backpack and it sucks a lot of power.
I have a Bioenno battery and controller, and I must say their products are superlative. Bioenno is also very responsive with customer support. I absolutely recommend them.