Tag: solar

Off Grid Ham: When Your Batteries Are Boiling

Chris at Off Grid Ham has an article up, talking about the danger/effect of heat on your batteries. When Your Batteries Are Boiling

Most of the USA is going through a blazing hot summer! Here in the upper Midwest it’s been over 90F/32C every day for almost two weeks. As I write this it’s 87F/31C in Buffalo, New York. That doesn’t sound too bad until you consider that it’s past sundown there, and the average daily July high for Buffalo is only 80F/27C. Most off grid amateurs fuss about battery temperature when it’s cold. Have you ever thought about what heat does to batteries? If you haven’t you should.

The chemistry of heat. battery temperature

How heat effects batteries varies greatly depending on the type of battery, how it is used, and the current going into/out of the battery. Battery chemistry, which is quite complex, is made even more complex by changes in temperature.

In addition to ambient heat, batteries themselves generate heat when they are charged or discharged. So, we have two factors at play. The radio amateur has only limited control over these two factors. Managing heat, to the extent that you can, will give your batteries better performance and a longer service life. battery temperature

Lithium batteries. battery temperature

Few things have benefitted amateur radio like lithium batteries. They are so much lighter and more powerful than their predecessors that the step forward in technology can plausibly be compared to when the transistor replaced the vacuum tube.

But like their ancestors, extreme temperatures effect lithium batteries. Once a lithium reaches 113F/45C, it should not be charged because excessive gas buildup can cause a cell to bulge. Lithiums can be discharged at up to 140F/60C but will lose capacity as they reach the upper limit of their operating range. There is also evidence that the higher the beginning state of charge, the more capacity will be lost as the battery heats up.

All larger lithium batteries have an on-board battery management system (BMS) that controls charging and cell balancing. Usually these electronics will reduce the current or not let you charge or discharge at all outside of acceptable temperature parameters. The high limits may seem generous, but do not underestimate them. Leaving a battery in a car on a hot summer day can easily push it beyond 113F/60C. If you are operating outdoors on a hot day and connect a solar panel to your lithium battery, the ambient temperature plus heat generated by the charge has the potential to exceed established temperature limits. The bottom line is, if your lithium batteries do not already have temperature-compensating circuitry, then you’ll have to monitor battery heat yourself.

AGM/Sealed batteries.

AGM, sealed lead acid, and gel cell batteries are cousins of each other and share similar characteristics. They’re very popular with amateurs due to their relatively low cost and ease of use. battery temperature

The top operating limit for AGM/SLA/gel batteries is 120F/49C. Like lithiums, AGM batteries will have reduced capacity at high temperatures and can also bulge/expand out. Thermal runaway is rare but possible. Overcharging generates heat and AGM batteries are especially sensitive to overcharging, so radio amateurs should be attentive when charging these batteries. A “smart charger” with a temperature probe would be ideal.

AGM-class batteries should not be discharged to less than 50% full. This presents a problem because they lose capacity at high temperatures. So if you have a battery that already has diminished capacity because it is hot, and then have to observe a 50% floor, that doesn’t leave much useful power for your equipment. At the same time, you will have to reduce charge current to avoid further overheating. The end result of all of this is a battery that will need to be charged more often and for longer periods. In a hot environment your AGM battery will for all practical purposes have less than half of its rated capacity. Lastly, long term exposure to heat will cut the service life of an AGM battery by half for every 15F rise above 77F (source)…

Click here to continue reading at Off Grid Ham.

Off Grid Ham: Small Solar Can Give Big Results

Chris Warren at Off Grid Ham has another good article up on small solar arrays for power, Small Solar Can Give Big Results…If You Play It Right.

Call now! Operators are waiting! small solar power

You’ve probably seen the campy ads hawking small solar power systems and “solar generators”. These ads make some remarkable claims and the manufacturers are deliberately vague on the technical specifications of these products. They further fuzz up the facts with unrealistic depictions of hypothetical situations. small solar power

I especially get a chuckle from the TV commercial showing happy, cheerful kids playing a board game in a large, well-lit house during a power outage and raging storm outside. The entire house is powered by, we’re supposed to believe, the advertised product which is a small battery pack weighing almost nothing and fits under the bed. Are small solar power systems worthwhile, or are they junk? As anyone with at least one functioning brain cell should suspect, the truth lies somewhere in the middle grey area.

Pictures are better than words. small solar power

This video was recently posted to the Off Grid Ham YouTube channel. It’s just over three minutes long and demonstrates the power of small scale solar.

Small scale solar has been addressed on this blog before, and my advice is still the same. If you are looking to take amateur radio off grid with solar, your best option is a purpose built home brew system made from components that you personally selected for your application. Furthermore, a DIY system is almost always less expensive. If you don’t care about cost and just want a plug-and-play “solar generator,” then by all means go drop several hundred dollars for a glorified battery in a box (you’ll lay out another few hundred on a matching panel to charge it). To be fair, it’s a very cool looking box but in the end you’re only paying for looks so in that regard you’re getting your money’s worth. small solar power

I’m not knocking the functionality of these products. They actually do work very well if used within reasonable expectations. I’m sour on them because of their breathtaking price tags and marketing that vastly oversells their capabilities. The ads are targeted to non-technical people who will not bother or know to ask the right questions. The technically-savvy people who know what to look for will have a hard time finding even basic specifications such as amp-hour ratings on batteries. The information is usually dumbed down with generic statements like, “runs a laptop for twelve hours!” small solar power

The bottom line: They work, if you keep it real.

small solar power

Off Grid Ham original photo ©2017

The bottom line is that small solar power systems do work, up to a point. Forget about powering your house through a storm with anything that will fit under a bed, unless there is physics-defying alien technology out there I haven’t heard of yet. But if you need to run a QRP radio, charge up your handhelds, and have some juice leftover for other needs, a little 50-150 watt solar setup paired with a modest battery should suit the job just fine. And you don’t need to plop down six hundred-plus dollars to do it.

In the video a continuous 50 watt load is easily supported by the small system. It gets better: The system in the video is overbuilt for a 50 watt load. I used it for demonstration purposes, but you could get by with much less…(continues)

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

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?

Organic Prepper: How to Deal with Rolling Blackouts: Notes from South Africa

In this article from the Organic Prepper, a South African writes notes about dealing with rolling blackouts and alternate forms of power like generators and solar power. It has some good information on battery cycles and reducing your loads. While I haven’t seen as much damage to equipment from power outages as the author of the article, it does happen. Some power utilities will help you put in a whole house surge suppressor. Our local utility will put one in at the meter for around $6 per month charge.

Living in South Africa we have had our share of rolling blackouts nationally. The cause: nefarious activities. The result being us forced to find ways to ensure we are not affected as badly.

The problem is better now, but it has highlighted that it is not just a South African problem, but in actual fact a Western world problem. We all are totally reliant on a massive aging infrastructure that can come tumbling down like a house of cards, with or without help.

Another problem is the cost to keep the national system operational. In some areas, it is not a priority to resolve the regular failures.

For getting started with backup power, remember that NEEDs vs WANTs –  a huge price difference.

  • UPSs – with like 2 up to 8 100ah batteries. Good for a number of hours depending on use – most cost-effective solution
  • Generators – works for some, but cheap ones cost more as they damage some electrical appliances over time.
  • Solar inverters and panels – power failures, what is that? And you save a lot of money afterward IF YOU DO IT RIGHT.

What is also good to know, when the power goes off, switch off your distribution board, leaving just the light plugs on. When the power comes back on, lights come on, wait a few minutes for the grid to stabilize, before switching things on. We have lost computers, internet modes, freezers/fridges, alarm systems etc, damaged when the grid goes off and back comes on. UPS’es have the best protection for this.

How does one solve the issues from frequent blackouts?

Here are some pertinent notes from my own experience.

  • Older fridges/freezers have a huge start-up current, necessitating a bigger inverter and they use a lot of kWh over 24 hours. Upgrade them to an A++ or even A+++ model, as soon as you can. It will save you on utilities and can be powered longer on batteries.
  • Lights: obviously CFL and / or LED, and not cheap LEDs. They are cheap for a reason. Test the wattage, it may be more than the claimed wattage “saving” you nothing. Check the claims lumens.
  • Putting lights on solar is not a “savings”. It is actually an increase in cost for batteries are more expensive per kWh than utility power costs per kWh because lights are use when there is no solar power. So switch to the best lumens for the lowest watts, and switch the light off when not in use, biggest saving ever.
  • Stove/oven/kettle – entire kitchen – on solar power is doable, but expensive. Utilities are cheaper. Kettle take few minutes to boil, microwave also a few minutes, why spend more on inverter and batteries to power them. Use gas. Gas per unit of power may not be cheaper than utilities. Check what you are paying for each.
    Maximum savings are: Switch off at the wall, not in standby, for all the standby power adds up to a lot of power paid for, yet not used.
  • When all the occupants of a house are asleep, say 11pm – 5am – how much power is used during that time? Excluding alarms and outside lights – which have a motion sensor to switch on. Figure this out and find places to cut.

The Rules of Running Backup Power Efficiently

Right, now that you have a few notes to consider, here are the rules that we have found important when using backup power like a generator.

The very first rule: NEEDs vs WANTs

Needs are much cheaper than wants, like you WANT to power your entire house during a power failure, or do you just NEED to power very selected devices like a fridge, lights, cell phone chargers?

The second rule: Know your loads and runtimes and match the batteries to that…

Click here to continue reading at the Organic Prepper.

Off Grid Ham: Grounding Your Off Grid System

Chris Warren over at Off Grid Ham has a nice article about the often confusing concept and execution of system grounding in Grounding Your Off Grid System. He’s not just talking about grounding your communications gear, but also your solar panels, and generators. Don’t get burned; learn to ground.

It’s hard to follow.

One issue that seems to come up a lot in the off grid radio realm is proper system grounding. The rules and expectations are hard to follow. There are a lot of opinions out there. Many of them are accurate, others are not. Today we’ll go over some basic grounding principles for off grid ham radio. This is by no means a comprehensive guide.

All the same basic grounding concerns with commercial power also apply to off grid energy. Electricity does not behave differently just because it comes from a renewable source. Finally, lightning does not discriminate!

What exactly is “ground”?

In the most simple terms, “ground” is a reference point. If you remember your basic electricity training for your amateur radio license, voltage is an expression of potential energy. However, potential doesn’t mean anything unless it is compared to something. For example, if you are standing on the roof of your house you have potential energy (via gravity) when compared to your yard. If you are laying flat on your back in your yard you have no potential energy compared to the yard because, after all, you’re already in the yard. You can’t fall if you’re already down, right?

Electrical grounding works the same way. Electricity needs a place to go, and it will not go anywhere without potential. Ground provides an electrical reference point. This has many implications for the operational effectiveness and safety of your off grid system.

Grounding outdoor equipment.

If electricity needs a place to go, it’s best for it to have a defined safe path instead of letting it find its own way. Off grid hams should place a high priority on grounding antennas and solar panels.

Connect (bond) solar panel frames together with 6 gauge copper wire attached to a conductive metal pipe or rod pounded into the ground. Be sure also to connect any metal support structures. Grounding lugs made specifically for solar panels are available from many sources including (of course) Amazon. Ground rods should be at least six and preferably eight feet deep. Getting a ground rod down that far will be a problem for many hams. You can substitute two or more shorter rods in place of one long one (be sure to bond the rods to each other).

GROUNDING

OFFGRIDHAM.COM ORIGINAL GRAPHIC ©2019

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

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