Nickel Iron Batteries
Iron Sun Kits
Living Energy Lights products are very different from typical off-grid solar kits. Our products all use DC (direct current), and none of our products are designed to be a general power supply for conventional AC (alternating current) appliances. Instead, our products are designed to provide specific services. Iron Sun kits provide lighting and charging for efficient 12 volt appliances. Daylight drive appliances like insulated solar electric cookers use energy straight from a photovoltaic panel without battery backup.
Our products work just fine as stand alone, household scale systems. But for best results, we recommend using them along with other daylight drive appliances and solar thermal systems as an integrated, village scale DC Microgrid. In the context of a DC Microgrid, our products can provide almost all of the services that grid power can, at a much lower financial and environmental cost. The team at Living Energy Lights has been living off the grid for ten years. Our DC Microgrid, which includes an Iron Sun Homestead kit and Roxy Oven, has been providing all the energy needs for a dozen people since 2010. We know our products work, because we live with them every day.
Our systems are durable. With mindful use, the main components of Iron Sun should not need replacing for 40 years or more. Every AC-based solar kit on the market has significant battery replacement costs- $1,000-$2,000 per year (or more) is not unusual.
Our systems are repairable. If a wire comes lose, or one of the smaller components wears out, the kit is easily repaired. The purchase of an Iron Sun kit includes free technical support for the lifetime of the product. No solar kit on the market is as repairable as Iron Sun.
There are no sudden power outages with our products, as there are with AC systems. If you draw down the power more quickly than the batteries can support, the lights will dim slowly, and you have time to adjust your power use. (See “What’s the problem with AC?” and “Is it true that nickel iron batteries charge and discharge more slowly?” for more details.)
Because Iron Sun kits and Sundanzer refrigerators are stand-alone systems, they can be added incrementally to a home energy system, as resources allow.
Because nickel iron batteries are not damaged by storage, Iron Sun boxes are uniquely suited for emergency back-up power.
The biggest disadvantage is the initial investment in DC equipment. For the most part, you cannot use our systems to power your existing AC appliances. (There are some appliances that run AC or DC, including many kitchen or shop appliances. See “What is daylight drive?” for more details.)
Swapping out new appliances may seem daunting, but it is a long-term investment in energy self-sufficiency. There is no other system on the market with near-zero operational costs. With a DC Microgrid and an Iron Sun Box, you will have no electric bills, and no expensive battery replacements – for the rest of your life!
Another consideration when using our products is that users must pay attention to the timing of energy use. We don’t truly consider it to be a disadvantage to deepen our awareness and relationship to the natural rhythms and resources that sustain us. Our community of a dozen people has lived happily with these systems for the past decade. It is not a sacrifice, but it is a different lifestyle.
If you want to live off grid, converting to DC (direct current) will save you a lot of money in the long run. Here’s the problem with AC. Every PV panel and battery generates DC electricity. The only advantage of AC, and the reason it has become the standard, is that it can travel long distances. This efficiency over a distance doesn’t matter at all for the off-grid homestead. But for an off grid system to power AC appliances, an inverter must be used to turn DC into AC. The inverter itself is a constant load on the batteries, which means the battery bank must be much larger in an AC system than a DC system.
When a battery bank powers an inverter to run a small load, like a phone charger or light bulb, more of the electricity goes into powering the inverter than the load. And when the battery bank falls below a certain voltage (which is inevitable during cloudy spells), the inverter shuts off completely. No power is accessible even for very small loads, because heavier loads- like the refrigerator, or even the inverter- have drawn down all the power.
Iron Sun Boxes use a small, durable battery set, and Sundanzer refrigerators use no batteries at all. This design keeps costs very low. The combined cost of a Sundanzer DDR and an Iron Sun Homestead kit is about $120 per year of service. A typical off grid AC-based system, on the other hand, costs $1,000-$2,000 every year to replace the batteries and inverters, in order to save a few hundred dollars up front by running cheap refrigerators and other AC appliances. It’s the ultimate penny wise, pound foolish mentality. Investing in good DC equipment, thermal storage and insulation, will save you many thousands of dollars in the years to come.
Daylight drive is the best way to power heavy loads in a DC Microgrid. In daylight drive systems, we wire PV panels directly to DC loads, with no batteries, inverters or charge controller. Because daylight drive appliances only run when the sun is shining, work must be done during the day, or alternative energy storage (like thermal storage, or pressurized water) must be used to provide services at night and during cloudy spells.
Because voltage and wiring requirements are different for heavy loads, a daylight drive system must be wired separately from an Iron Sun box.
Some DC appliances suitable for daylight drive are available on the market, such as DC pumps and Sundanzer refrigerators, that do not require any altering or external switches. Sundanzers use thermal storage to stay cool at night and during cloudy spells. Daylight drive DC pumps are perfectly suited to run irrigation systems during the day. They can also be used to charge pressure tanks or a gravity powered system for domestic water supply.
Another way to use daylight drive is to power an industrial DC motor connected to belt drive equipment, like old fashioned shop tools and tractor implements.
Generally speaking, conventional AC appliances cannot run daylight drive, but there are a few exceptions. These include resistive loads and universal motors. Resistive loads- those that make heat, like hot plates for cooking- will run daylight drive, but take the full capacity of the system, and do not run well in anything less than full sun conditions. It’s important to note that external switches must be installed to run these appliances with DC. DC current will melt switches designed for AC.
DC Microgrids provide a means for decent energy services to be provided by a modest budget of renewable energy alone.
PV panel and windmills are not environmentally free, their manufacturing has a significant carbon and toxic footprint. On top of this, the most difficult and costly part of renewable energy systems, both financially and environmentally, is energy storage. Industrial solar and wind must be backed up by a fossil fuel capacity equal to these intermittent renewables. It’s economical for the utilities to keep these “back-ups” running at near capacity, so (surprise!) that’s what they do. At peak solar production, a lot of the extra power gets burned off in giant heat coils, because it’s cheaper than shutting down and restarting the natural gas or coal plants.
There has been growing excitement about large scale lithium battery storage for renewable energy, but this is a pipe dream of the wealthy. The environmental implications of such scale of battery manufacturing and disposal is mind-boggling, not to mention prohibitively expensive.
With grid tie there is no incentive to conserve, or use electricity when the sun shines. It perpetuates the illusion that electricity is cheap, abundant and always available. In the meantime, future generations- and communities at the front lines of fossil fuel extraction- ultimately pay the bill.
There is no battery technology available that is as durable as nickel iron. In terms of rated capacity per dollar, lithium and lead acid seem to be cheaper than NiFes, with lead acid in particular looking very cheap on paper. But they will perform as rated the day you buy them, and not much longer. If they are not kept “topped off” by grid power or a generator, lead acid will typically drop to 50% capacity by year two or three, and by year four or five, they are pretty much useless. Lithium doesn’t perform much better- a four to seven year useful life is typical for deep cycled lithium systems.
The ability to use the full capacity of a battery is a big deal for living off-grid. At Living Energy Farm we don’t have a back-up generator, and we cycle our batteries pretty hard. The nickel iron batteries in our Iron Sun Homestead kit are ten years old and performing at 150% of their rated capacity. If we had lead acid batteries, we would have replaced them twice by now; with lithium, at least once.
Our battery supplier considers their NiFes to have a 40 year lifespan, but NiFes have been known to have a useful life far beyond 40 years. To test this claim, we bought an 80 year old NiFe battery- one of the first made by Thomas Edison- which had been neglected for years. We brought it back into service, and amazingly, it is performing at 50% its rated capacity.
There are other environmental benefits of NiFes, beyond their durability. In fact there is no battery technology available that is as safe and non-toxic as NiFes. NiFes are perfectly safe to store in your home because there are no toxic electrolyte or metals. Lead acid batteries are highly toxic and must be stored outdoors. Lead acid batteries used in the US are sent overseas to be recycled because the process is so toxic. Lithium battery disposal is toxic as well, and they also require scarce materials which are causing conflicts around the world.
NiFes are made of iron, which is super abundant, and nickel. Nickel is not as abundant, but there are nickel deposits in several places around the world, so the mining process is not as likely to cause conflict as is mining for the rare earth metals needed for lithium batteries.
One of the criticisms of nickel iron batteries is that they have a slow discharge rate. It’s true that NiFes are not great for a providing surge of power, like starting a car. But when used in an Iron Sun box, for a consistent output of a small amount of energy, this slow discharge rate is a NiFe’s biggest asset.
Have you every had the experience of walking along with a flashlight as it runs out of power? The flashlight gets a bit dim, then suddenly goes out completely. That experience of “going over a cliff” never happens with NiFes, as long as you maintain a modest draw rate. Let’s say you get our Iron Sun Cabin Kit. It’s a cloudy day, you’ve been running a few light bulbs, charged your tablet, and you notice the voltage dropping. At this point, turn off a load, and watch what happens. The voltage drop will slow down. Get down to the optimal discharge rate, and the voltage might even increase, with no power coming in! The optimal discharge rate is the rate at which the electrolyte can move in and out of the fine perforations in the plates inside the battery. At this optimum rate (which is lower than the full power rating), a nickel iron battery can sustain output for a very, very long time. There is no “cliff.” For living off grid, the fact that there is no cliff, no point where our batteries just give up, is a lifesaver.
It is true that nickel iron batteries must be topped off with distilled water at regular intervals. When NiFes are used as recommended in our Iron Sun box, this interval is once per month. Other websites claim that NiFes need to be watered weekly. We have never found this to be true, although if they are charged with a oversized PV panel and no charge controller, they will boil off electrolyte more quickly.
Another criticism of NiFes is that they off-gas flammable hydrogen gas. This is also related to how hard the batteries are being charged, and how big the system is. For a very large system, cycled hard in an air sealed room, the off-gassing could in theory be a concern. Iron Sun boxes are small, and in a room with reasonable ventilation, they do not represent a fire hazard from off-gassing hydrogen.
Great question! The short answer is that technology moves towards what is profitable, not what is functional. Sometimes what is most functional is also most profitable, but not always. Nickel iron batteries were invented by Thomas Edison and originally manufactured in New Jersey, but over time every American nickel iron manufacturer switched to other batteries that made them more money. Now they are only made in China and the Ukraine. That’s because it is more profitable for manufacturers to make a disposable battery than a durable one.
Consumer demand has not driven the large scale development of NiFes because they have low power density (output per weight). They are not practical to put in a cell phone. But for stationary use, or any application where weight is not a liability, they are great. Their bulk is a large part of what makes them so durable.
Depends on what you want to do with it. Generally speaking, the larger the system, the more battery capacity you get for your money. But if you only need a small number of lights (less than 5) and to charge your phone, or for occasional emergency back-up, the Cabin kit is fine. Consult the chart below to see if one of our smaller kits will meet your needs. If not, we recommend the Homestead kit.
While battery capacity limits nighttime use, Iron Sun boxes are compatible with any 12 volt DC appliance under 120 watts that uses a cigarette lighter plug. There are many on the market for truckers, RVs, and sailboats. Some examples are listed below.
Please note: The links below are for informational purposes only. We have not quality tested any appliances except those available through Living Energy Lights.
To approximate the amount of power your Iron Sun box will provide at night, divide the watt hour rating of your battery by the number of hours you expect to use the power. That is how many watts you can run at night after a sunny day. During overcast spells, you will have less power available.
The main components of an Iron Sun kit- the nickel iron batteries and PV panel- will perform for many decades, although their output will decline after 40 years or so. They are capable of putting out a useful amount of power for 80 years or more.
A PV panel is considered to have a 50 year useful life, because they lose about 1% capacity per year, meaning that after fifty years, output will be less than 50% of its rated capacity.
Our nickel iron battery manufacturers rate their battery to have a useful life of about 40 years. If maintained properly, NiFes will store a useful amount of power for longer than that. We revived an 80 year old NiFe that had been neglected for years, and it performs at 50% capacity.
The small components of an Iron Sun box- switches, fuses, outlets, etc- might fail at some point, probably while the main components are still functional. If this happens, contact us and we can help you diagnose the problem, source the replacement parts, and repair your box. Replacement parts for the smaller components will cost you $5-10 (on average) plus shipping.
Yes, definitely! They are the best solar kits on the market for a long term investment in emergency backup.
It comes down to the batteries. Nickel Iron batteries can be stored for years and brought back into service without loss of capacity. This is not true for lead acid or lithium, which are both damaged by storage.
Discharged NiFes will take 2-3 days of sunshine to come up to full charge. If you want to have your back-up system ready for use immediately, keep the box connected to a PV panel in full sun. You will have to put distilled water in your batteries once per month if they are connected to a PV panel, even if they are not being used.
While Iron Sun boxes are uniquely suitable for emergency back-up power, we don’t recommend you stick them in a closet. We recommend that you unplug yourself from the electric grid and start using our products today!
The most important ongoing maintenance is to top off the electrolyte with distilled water about once a month. Your batteries will be damaged quickly if cycled with insufficient electrolyte. Do not use tap water, well water, or anything other than distilled water to top off your batteries, as the mineral content in undistilled water will destroy your batteries very quickly.
It’s important to keep your PV panel clean and in full sun. Even a small amount of shade or debris on the panel will drastically reduce its output. Don’t forget to wipe the snow off your panel as well.
Although nickel iron batteries will tolerate deep cycling more than other batteries will, maintaining voltage above 10.5V will keep your batteries and appliances happy for longer. Very low voltages will cause the amerage to spike, which can damage fragile electronics.
While in use, an Iron Sun box should be kept in your living space, close to where power will be used. All batteries, nickel iron included, perform best if protected from extreme heat and cold. Another benefit of keep the box in your living space is that it keeps wire runs to a minimum, which will also improve performance.
If you are storing your kit for emergency backup, it’s okay to store it in a shed or unheated building, but don’t leave it out in the rain. It does not hurt the batteries to store them uncharged, but it does take one or two days for the batteries to reach full voltage if they are stored uncharged.
Iron Sun boxes are wired at 12 volts, which does not present an electrocution hazard. However, any electrical system can start a fire if connections are not done properly. It is important that all electrical connections, inside or outside the box, are done by a qualified electrician. Twisting wires together and covering them with electrical tape might work in the short term, but in the long term these amateur connections will fail, and might start a fire.
In regards to toxicity and off-gassing, nickel iron batteries are the safest battery you can buy. They are non-toxic, and off-gassing is not an issue with our small systems. The electrolyte, potassium hydroxide, is highly alkaline and can cause eye damage, but it is contained safely in the battery as long as the battery stays upright. Therefore it is important to keep the box upright to prevent spillage, and to keep children and pets from opening the box and playing with the wires or batteries, which can create a fire hazard. Put a strap and padlock around the box if this might be an issue.
Once a month, you will need to top off your battery with distilled water. This is a very safe process that does not put you in contact with the electrolyte.
Every 8-10 years, we recommend changing the electrolyte in your battery. We will provide instructions on how to do this with the purchase of your Iron Sun kit. Care must be taken during this process to prevent eye damage from the corrosive chemical, and to prevent contamination of the electrolyte, which would impair the performance of your battery.
The Iron Sun kit comes fully assembled and ready to use if you plan to use lamps for lighting. You will need an electrician if you wish to install overhead lights, or convert your existing lighting fixtures.
You will need to mount your PV panel in full sun. This requires light carpentry skills, and we do not include mounting hardware, because every situation is different. Feel free to contact us if you have questions about how to mount your panel.