Tag: battery

Off Grid Ham: Jumping Off the Grid for Beginners

Chris Warren at Off Grid Ham has written an off grid radio guide for those who are beginners to working their radios without mainline power. There are a bunch of useful links at the end of his article, too.

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!

off grid radio guide

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…

Click here to continue reading at Off Grid Ham.

The Medic Shack: The Powergrid. Is it as screwed up as we think it is?

The Smart Survivalist: Off-Grid Batteries and Power Systems

The Smart Survivalist: How Much Does it Cost to Live Off Grid?

OH8STN: Emergency Power for Communications

Amateur radio enthusiast, blogger and vlogger OH8STN (Julian) has posted the second video in his Grid Down Communications series. In this video he addresses peoples’ concerns with how they will keep their communications online when the grid is down, including batteries, solar generators, solar panels, and other alternative power.

PNNL Lecture: Redox Flow Batteries for Energy Storage, Jan 15, 2019

The Richland Public Library is hosting a PNNL lecture on Tuesday, January 15th at 7:00 PM on Redox Flow Batteries (RFBs) for Large-Scale Energy Storage. Some battery manufacturers are starting to make RFBs available for home solar storage, so this may be an up and coming technology, though issues may still be being worked out. Manufacturers call them the safest and cleanest energy storage solution, and that the risk of battery fire is eliminated. RFB lifespan is also suggested to be longer with more than 10,000 power cycles with no degradation.

PNNL develops large scale RFBs for utility-level storage, like the 8 Megawatt-hour battery installed at a Snohomish PUD substation back in 2017.

PNNL Lecture – Redox Flow Batteries as Candidates for Large-Scale Energy Storage

Redox flow batteries (RFBs) are prominent candidates for large-scale energy storage because they offer high safety, decoupling of power and energy, long life span, quick response, and potentially low cost. This talk will introduce this unique energy storage technology to the Tri-Cities community, and provide an overview on its working mechanism, development history, major components, and the various chemistries used.
The talk will also cover new redox flow technologies developed at Pacific Northwest National Laboratory.

Presented by Dr. Wei Wang, Chief Scientist, Energy Processes and Materials Division

 

Off Grid Ham: Introduction to AC Inverters

From Chris at Off Grid Ham, An Introduction to AC Inverters. Even if you’re already happily running all of your ham radio equipment off grid, at some point you might wish you could run something that wants 120V AC. If you’re not a ham radio operator, and you’re looking into running some household stuff from a battery/solar system, then you also are probably interested in learning something about AC inverters.

AC inverters are like other technology in that during the early  years they were very expensive and didn’t work particularly well. Over time they were tweaked and improved and today inverters are better and less expensive than their ancestors. I suggest including an inverter in your off grid plans even if you don’t think you need one because the day may come when it will be an essential asset. Furthermore, if you have any intentions of owning a larger solar energy system to power common household devices, then a familiarity with AC inverters is a must…There are three basic types of AC inverters on the market: Square wave, modified sine wave, and pure sine wave. Which one will work for you depends on what you plan on powering and of course your budget…

Click here to read the entire article at Off Grid Ham.

Off Grid Ham: How Much Battery Do You Need?

Chris Warren over at Off Grid Ham has a nice article up, How Much Battery Do You Really Need? The article discusses how much radio time you can get from a battery, or conversely how much battery do you need to run your radio.

It’s always some variation of “How big of a battery do I need to run my (fill in the blank) radio?” It comes up a lot, not just in my email but also on the various forums and blogs I visit. The question is too open ended and comes with too many variables to give a definitive answer, but there are some basic battery concepts that will help you sort through this confusing topic.

Before asking the question, provide some answers.
It certainly does not help that many of the answers floating around the internet are based on guessing, hypothetical conditions, and overly generous manufacturer data. Before you can know how much battery you “need”, first find out how much power all your stuff consumes and what you plan on doing with it in the real world. Off Grid Ham reader James (whose question was the inspiration for this article) asked about going off grid with his Yaesu FT-450 radio. The official Yaesu specifications state that this radio consumes maximum 22 amps/304 watts on transmit, and 0.55-1.5 amps/8-21 watts on receive depending on the audio level (these numbers are rounded).

Discharge reality.
James wants to run his radio with a 35 amp hour AGM battery and charge it with a 2 amp plug in charger. He plans on adding a solar panel at a later time. So what can he realistically expect from this setup?

A 35 amp hour battery can provide 35 amps for one hour. This is known as the C-rate or 1C-rate. The 2C-rate would be 17.5 amps for two hours, the 3C is 11.66 amps for three hours, and so on. Following the math, the 35 amp-hour battery should push James’ 22 amp transmitter for a little over ninety minutes. In the receive only mode, assuming an average of 1 amp, the battery will go for 35 hours.

But let’s deconstruct this…

Read the entire article at Off Grid Ham by clicking here.