Exploring Edison Batteries.

      20 Comments on Exploring Edison Batteries.

Revisiting the old school.

Most radio amateurs have never even heard of Edison batteries. Edisons been around for over 100 years, and while they enjoyed some early popularity, they more or less left the scene by 1910. Lately though they’ve been getting more attention from the off grid community. So what’s the deal with Edison Batteries? What makes them different than the rest? Are they for you? Here we go….

A quick history lesson.

Edison batteries, also known by the common noun nickel-iron (NiFe) batteries, were patented by Thomas Edison in 1901. This seems odd because Edison did not actually invent the device. That credit goes to Swedish researcher Waldemar Junger in 1899. The nickel-iron battery was supposed to be an improved version of the nickel-cadmium battery, which Junger also invented. He was never able to develop his nickel-iron battery into a practical technology so he abandoned the idea entirely, although he got far enough to earn a patent. Along comes Edison who brought his own ideas to the product, resulting in separate patents for what became the proper noun Edison battery.

Edison batteries were popular in early electric cars, then quickly faded into obscurity as gas engines took over the automotive market. For many decades after that, only niche applications used iron-nickel technology. Edison-branded batteries ended production in 1975 while other manufacturers continued to make generic versions in limited quantities to serve the few clients who still used them.

For the purpose of this article I will use the terms “Edison” and “nickel-iron” interchangeably.

Edison batteries

Photo courtesy of ironedison.com

Are Edison batteries a good choice for the off grid ham?

There is a lot to consider before jumping into nickel-iron batteries. Whether or not they are a good option for you depends on your situation, needs, and budget. More importantly, are you willing to give up the battery technology you’re currently using and replace it with something totally different? Laying out all the pros and cons may help you decide.

Edison battery-pros.

Very long service life: This is probably the biggest selling point of nickel-iron batteries. They can last decades with simple maintenance. You’ll probably hand them down to your children and possibly grandchildren. These batteries are usually rated for a 30 year service life, but this is an understatement. There are 60-plus year old units still out there chugging along! It is likely the last battery you’ll ever buy.

Survivalists/preppers planning for a complete societal collapse logically also believe the collapse will end commercial battery production. Therefore, what you have when SHTF is likely all you’ll ever have and procuring replacements will be difficult if not impossible. If this is your mindset, nickel-iron batteries should be a very serious consideration.

Deep discharge capability: Up to 80% discharge is not harmful to nickel-iron batteries. This is comparable to modern lithium batteries and far superior to lead acid flooded batteries.

Low maintenance: Top off the electrolyte every few months, and completely replace the electrolyte every 3-5 years. That’s it! There is no need to measure electrolyte density as it is not relevant to the state of charge. Also, you do not need to periodically equalize the cells.

Environmental impact: Edison batteries do not contain any heavy metals so their environmental impact is much less compared to conventional batteries.

Nearly indestructible: Edison batteries will easily tolerate overcharging, undercharging, deep discharge, and shorts. Aside from physically damaging the battery or willful abuse, it’s pretty hard to ruin one. They also cannot freeze and are unaffected by extreme temperatures. Typical operating temperature is -22F (-30C) to +140F (+60C).

Edison battery-cons.

High self-discharge: Edison batteries will self discharge at a rate of 1% per day. This effects the overall efficiency of the battery (which we’ll address in a moment). It does not sound like a lot, but cumulatively that’s a lot of energy you’ll have to account for just from your batteries sitting there. Think of self-discharge as a hole in the bottom of a water bucket. The bigger the hole, the harder it is to keep the bucket full.

Low charging efficiency: Charging efficiency is another manifestation of the hole in our “bucket”. Nothing is 100% efficient. You’ll never get as much out of any battery as you put into it. Edison batteries run about 65% efficient when charging. If your battery is being fed by a 100 watt solar panel, thirty five of those watts will be lost right off the top. This is above and beyond any other system losses.

Mechanical complexity: Edison batteries are manufactured as 1.20 volt cells, so to get 12 volts you’ll need to connect ten of them in series. You’ll also probably need to buy or build a rack to hold them.

In addition to the cost of the actual battery, amateurs should consider adding more charging capacity to offset the low charging efficiency. The table below compares the characteristics of common battery types with iron-nickel. The numbers are rounded/averaged due to variations between manufacturers. The weight measurements are for a 100 amp-hour battery:

edison batteries


Things that may not matter, depending on your situation.

There are a few things about nickel-iron batteries that can be either pros or cons, or may not matter one way or the other, depending on your needs and priorities:

Low energy density: This may not matter if you have a lot of storage space and do not require portability. As illustrated in the table above, nickel-iron batteries are quite large and heavy for the energy they produce. It’s more than double the weight of a flooded lead battery of the same capacity, and about five times that of lithium!

True cost of ownership: When amortized over their service life, the real cost of Edison battery ownership is comparable to conventional batteries. It’s also a hedge against inflation. But for the average off grid ham, it’s quite a stretch to justify laying out thousands of dollars today in exchange for a payback spread over decades.

Very high up-front cost: Prepare for massive sticker shock. In 2020 a standard 100 amp-hour flooded deep cycle lead battery costs, oh maybe $100.00 or so? A lithium is around $875.00. A similar capacity nickel-iron version will hit you for over $1000.00. That’s not a typo. On the upside, the Edison battery may last beyond your lifetime. Off grid hams have to decide for themselves if the long term savings is greater than the one time front-loaded cost.

Where do we go from here?

Jumping into Edison batteries requires a great deal of careful thought and calculation. My honest opinion is that very few off grid amateurs would benefit from them. In my mind, exceptionally long service life and tolerance for abuse does not supercede the high initial cost and other compromises inherent to nickel-iron batteries. After all, there is a reason why this technology has not been mainstream for over 100 years and is now used only in very specialized applications.

But that’s me. Your situation may be different. No matter which side of this you may fall on, you now have some clarity on which to base a decision.

20 thoughts on “Exploring Edison Batteries.

  1. Roy Eades

    Good reading, makes a person think and evaluate their real needs for “off-grid” power requirements. Thank you.

  2. Randall Krippner

    Thanks for the information. I’d heard the name Edison battery before, but I had no idea what it was or how it worked. Too bad about the cost of these things. The self discharge rate and inefficiency in charging could be dealt with. Even the size and weight wouldn’t be an issue in a stationary situation like a power supply for a house. But the cost – wow, that’s just nasty. That pretty much puts them in the category of only being affordable by the billionaires building their luxury bunkers out of old missile silos, at least for any kind of large scale energy storage.

    1. Chris Warren Post author

      Hi Randall, I agree. Edison batteries are not for me. But there are folks out there who would be a good fit and are willing to spend the money. For everyone else, knowledge is always worthwhile.

      1. Randall Krippner

        Knowledge is always worth the effort. And who knows? Perhaps getting more information out will result in people doing more research and perhaps coming up with a way of bringing the cost down, as is the case with lithium batteries. A whole home solar system is now available for about the price of a new car but the problem is storing enough energy cheaply to keep the house running at night and during bad weather.

  3. JustSumDad

    I am new to the ham radio world, just working on my basic now actually, but I would think that lithium iron phosphate would be a go to power storage system with a very low self discharge rate and recharge cycle life up to 2000 cycles…
    Just my thinking.

    1. Chris Warren Post author

      Hello, and welcome to ham radio! You are on the right track. Lithium batteries are probably the best technology currently available, and as the product matures the cost will come down.

    2. Randall Krippner

      You’re right, Justsumdad. At the moment the LiPo designs are probably the most cost effective. Like Chris said the cost is coming down every year. As is the cost of solar. I was just looking into it and I could put in a complete Tesla power system for about $50,000. That would include a 10kWh solar roofing system and two PowerWall units for energy storage. That may sound like a heck of a lot of money, but if you stop and think about it that’s less than a lot of cars and trucks sell for these days. And if you’re willing to go through the work, you could roll your own and end up with a similar system for a heck of a lot less.

      I’m going to need a new roof on the house in the next few years, and that’s going to cost me at least $15,000, so am I being ridiculous by considering going with a solar roofing system at $30,000+ that’s also going to generate a significant percentage of the electricity we use in the house?

  4. JustSumDad

    I was actually thinking of LiFE aka LiFePO4 formula not LiPo – That’s Lithium IRON Phosphate rather than Lithium Polymer.
    With LiFE voltage per cell is around 3.7v so lower than LiPo that runs 4.1-4.2v but with advantages in charge cycles and even lower self discharge than Lipo. Also the discharge of the LiFE is so flat that it makes it hard to use a volt meter to check the charge 🙂
    LiPo would a lower initial cost but with a charge cycle in the 300-500 range and the LiFE chemistry offering up to 2000!! Well LiFE would be the lower cost in the long run.
    LiFE can also run down to a lower voltage before damaging the cells, LiFE cutoff at 2.2 where if LiPo is discharged below 3.0v you lose a lot of capacity.

    When building any lithium based power system low voltage cut off is a very important feature!

    1. Chris Warren Post author

      There are many types of lithium batteries. The most common are the LiFePO4 as you mention. I use them for my portable QRP bag and a few other small applications, but they are still too expensive to deploy in my home system. In addition to the 600 amp-hours of batteries, I’d need to replace my charge controller too. I’ll be on lead acid for a while, I think.

      Thanks again for your input.

  5. Larry Nixon

    Good info. We used these to power fire lookouts years ago. I sent crews up over several days to pull them all out for recycling.

    I knew a ham in the early 90s who used them. He had a line of them running through his basement. Got them surplus from a railway I believe.

    Still think i will stick with my lead acid and Lipo though.

    1. Chris Warren Post author

      Hi Larry, yes railroads were and still are the biggest user of nickel-iron batteries. Like you, I considered nickel-iron batteries but ultimately decided to stick with lead acid and lithiums.

      Thanks for stopping by Off Grid Ham

  6. Goldrider

    Hi Chris,

    Nice article.
    I have 24V NiFe battery bank Am am using with my solar panels

    From the points you mentioned:
    regarding solar use.
    (Just in my humble opinion)

    – Regarding weight: I found them actually less weight then Lead Acid (LA) But they’re bigger.
    Doesn’t matter that much for offgrid use. But let me be clear though: both LA and NiFe are not ideal
    for mobile applications.

    Self discharge: I find _much_ lower self discharge then 1%. But even at 1%,
    it does not matter for off-grid usage. (charge and use every day)

    – They don’t sulfate (like LA does) No sun for a week? No worries!

    A disadvantage is that they are a wet style battery
    You are required to check the elektrolyte levels and fill with destilled water when needed.
    I am averaging around the 3 months between watering.
    On the positive side, you can recondition them with new elektrolyte.
    Making KOH (=lye) is a fairly simple affair.
    I made it at home and filled them up, no problem.

    Price is not cheap: but do consider you cannot drain a 100Ah LA battery to say 50% depth
    of discharge if you want it to last for any lenght of time. So you would
    need more LA batteries to math a comparable NiFe of NiCad set.

    It would not make the NiFe’s cheap, but the price gap is lower in that regard


    1. Chris Warren Post author

      Hello and thanks for your comment. I like the longevity and (relatively) low maintenance of Edison batteries. As for the rest…I’m not sure the pros outweigh the cons but the point you make about discharge is valid.

  7. Rhodes

    I’m a ham operator and I’ve been working with nickel iron batteries professionally for several years now. Even though I think NiFe batteries are the best thing since sliced bread, they are not a good diea to directly power 12v Ham radio equipment due to their large voltage window. A 12v NiFe bank (10x 1.2v batteries in series) has a charge voltage of 16.5 – 17 v, and will drop down to 11.5v when they’re at a 20% state of charge. I don’t know of any Ham radio gear that will operate under those extremes. Most radios want a constant 13.8v, or at least 12-14v. There’s a good chance your radio would release the “magic smoke” if it was exposed to the NiFe’s 17v charge voltage. If you have a DC-DC converter or regulator, then they’d be a great solution, but directly powering your shack with nickel iron batteries is not a good idea unfortunately.

    1. Chris Warren Post author

      Thanks for your insight and experience. You are absolutely correct: Some kind of voltage regulation is probably needed. MFJ and I think West Mountain Radio have off the shelf products that will perform this function (they are not cheap). There are also many, many on line articles and YouTubes with DIY versions.

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