Nickel-Iron batteries

Built for off-grid: modular 1.2 V cells build 12/24/48 V banks
🛡️ Fail-safe by design: no BMS,  non-flammable alkaline electrolyte
EMP-resilient: chemistry keeps working when electronics don’t
🌡️ Cold-ready: wide operating range
🔋 Abuse-tolerant: handles deep discharge, overcharge
🔧 Field-serviceable: performance can be renewed via electrolyte refresh
🔁 Decades of service: century-proven NiFe chemistry
♻️ Sustainable & recyclable: steel plates and alkaline electrolyte

 🛡️  Download DATASHEET (PDF)

THE ORIGINAL, INDUSTRIAL-GRADE EDISON BATTERY.

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Nickel-Iron battery : Europe-made, ultra-durable battery

⏳ Long-Term Reliability

Proven power for remote and demanding environments

NiFe batteries deliver decades of service without the failure modes seen in lead-acid systems.

  • 🏔️ Built for remote reliability: ideal where maintenance access is limited.
  • 🛡️ No classical degradation: no sulfation, no stratification, no corrosion-driven shorts — unlike OPzS/OPzV.
  • 30+ year lifespan: significantly outlasts li-ion technology under normal use.
  • ♻️ Performance rejuvenation: simply renew the electrolyte instead of replacing the pack.
  • 📚 Century of data: extensively documented field behavior — predictable and trusted.

NiFe batteries are an excellent choice for remote locations where reliability and longevity are the primary factors. These batteries do not suffer from the degradation effects commonly seen in lead-acid batteries (electrolyte stratification, sulfation, electrolyte deterioration, electrode corrosion leading to internal short circuits), even in the best versions (OPZ). The average lifespan of a Nickel-Iron battery is over 20 years under normal use, with the added benefit that its electrolyte can be replaced to rejuvenate its performance. Nickel-Iron batteries have over a century of proven performance, and their behavior in the field has been extensively studied and documented in specialized literature.

Nickel-Iron battery

Unparalleled chemistry : Nickel-Iron for durable storage systems :

Edison once claimed that his batteries were designed to last a century. While Edison, being a brilliant businessman, certainly knew how to craft a compelling sales pitch, there is documented evidence of a 1934 batch of Nickel-Iron batteries where 50% of the capacity was recovered (link).
Although they are more expensive upfront compared to the best lead-acid batteries, this is justified by the cost of raw materials (Nickel), and the investment is offset by a low total cost of ownership.

Their high tolerance to abuse (prolonged partial charge, short-circuiting, extended deep discharges, mechanical shocks, freezing) provides great peace of mind, making them particularly well-suited for the harsh conditions often encountered in off-grid setups.

Rugged batteries that are built to last :

Unmatched in robustness and longevity since their invention in 1901 by Thomas Edison and W. Jungner, NiFe batteries fell out of favor in the 1970s, overtaken by the more affordable lead-acid batteries, and later by lithium-ion in the 1990s. The exceptional longevity of Nickel-Iron batteries is explained by their chemical properties (see PDF study).

The structural degradation of the components (iron electrode and nickel electrode) is virtually non-existent, thanks to an alkaline electrolyte that acts as a preservative for the metals, much like in Nickel-Cadmium batteries (as opposed to acidic batteries). Historically, they were used in challenging conditions such as subways, mines, and military aviation.

nickel-iron battery

For instance, some salvaged, old Nickel-Iron batteries dating back from 1930’s showed amazing capacity recovery after a couple of charging/discharging and an electrolyte remplacement. This is a testimonial to their exceptional longevity.

Nickel-Iron battery restaured capacity

Documented old Edison batteries manufactured in 1930 that were reconditioned to a decent capacity, in 2010.

The low tech design of the Nickel-Iron battery eliminates malfunction risks :

🔥 Safer By Chemistry

Non-flammable electrolyte — engineered for fail-safe power

NiFe batteries use a water-based alkaline electrolyte with no flash point — eliminating lithium-style fire risks.

  • 🔥 Non-flammable KOH electrolyte: no flash point — safer than lithium's organic solvents.
  • 🌱 Low toxicity + no harmful emissions: safer for environment and indoor systems.
  • 🪫 No BMS required: chemistry self-regulates — avoids electronics vulnerability.
  • 🔁 User-replaceable electrolyte: simply mix KOH technical grade with distilled or ionized water.
  • ⚖️ Trade-off for safety: ~80% efficiency vs >95% lithium — chosen for reliability, not fragility.
  • 🧱 Tubular nickel-plated construction: extreme mechanical shock resistance.
  • 🚗 Originally designed for automobiles: built for real-world vibration and abuse.

Nickel-Iron batteries use a non-flammable alkaline electrolyte, with no flash point, composed of an aqueous solution with approximately 25% potassium hydroxide (KOH).

Free from environmental toxicity and without harmful gas emissions, these batteries do not require electronic management systems (BMS), unlike lithium batteries, where the organic electrolyte does not provide a regulatory function in case of overcharging.
The electrolyte can be replaced by the user, using technical-grade potassium hydroxide powder and distilled or ionized water. The trade-off for this safety-oriented design is that Edison batteries have a lower efficiency (~80%) compared to lithium batteries (>95%).

The tubular design of the battery, where the electrode materials are enclosed in finely perforated, nickel-plated tubes, provides very high mechanical resistance (to shocks).

This is precisely why Edison initially designed these batteries to be used in automobiles.

Pocket plate design

Nickel-Iron is a great choice when power is critical

⚡ Off-Grid Reliability

Built for places where failure isn’t an option

Nickel-Iron systems deliver durable, field-serviceable power you can trust when the grid can’t.

  • 🪖 No BMS — EMP resilient: no delicate electronics required for safe operation.
  • ❄️🔥 Extreme tolerance: deep discharge, overcharge, and temperature swings without thermal-runaway risk.
  • 🧰 Field-serviceable: simple distilled-water top-ups and electrolyte refresh rejuvenate the pack.
  • 🏔️ Off-grid readiness: ideal for cabins, homesteads, telecom, wildfire or storm-prone regions.
  • 🛡️ Century-proven: engineered for decades-long service life based on Edison’s original durable chemistry.

Edison (Nickel-Iron) batteries can be relied upon when the grid can’t. Built on century-proven chemistry with no onboard BMS or delicate electronics to fry (EMP-resilient by design), they’re engineered for true fail-proof operation in remote power systems. Thick steel plates and an alkaline electrolyte tolerate deep discharge, overcharge, and wide temperature swings without the thermal-runaway risks of other chemistries. Maintenance is simple—periodic distilled-water top-ups—and even after years of hard use they can be rejuvenated with an electrolyte refresh. For cabins, homesteads, telecom sites, and storm- or wildfire-prone regions, NiFe delivers durable, field-serviceable power you can count on for decades.

Nickel-Iron batteries with SUNCONNECT prewired system

The long service life of the batteries lies in the chemistry :

🔬 NiFe Solid-State Chemistry

Stable solid-phase reactions — not dissolving chemistry

Nickel–iron stores energy through reversible solid-state redox without corrosion-driven decay.

  • 🔋 Solid-state redox: iron & nickel cycle between hydroxide/oxyhydroxide phases — not dissolved ions.
  • 🛡️ No corrosion or dendrites: electrodes don’t pit, crack, or grow lithium-like dendrites.
  • 🔥 No flammable SEI layer: no thermal-runaway interface to form, maintain, or destabilize.
  • 💧 Replaceable KOH electrolyte: acts as conductor and OH⁻ reservoir — can be renewed if carbonates build up.
  • ❄️ Legendary tolerance: survives overcharge, deep discharge, and temperature extremes for decades.
Nickel-Iron batteries

Nickel–iron battery store energy through highly reversible, solid-state redox reactions in a strongly alkaline electrolyte (typically KOH). During discharge, the iron negative electrode is oxidized from metallic Fe to ferrous hydroxide, releasing electrons (Fe + 2 OH⁻ → Fe(OH)₂ + 2 e⁻), while the nickel positive electrode is reduced from nickel oxyhydroxide to nickel hydroxide (NiOOH + H₂O + e⁻ → Ni(OH)₂ + OH⁻). The overall reaction is a phase change between insoluble hydroxides/oxyhydroxides: Fe + NiOOH + H₂O → Fe(OH)₂ + Ni(OH)₂. Charging simply drives these steps in reverse, regenerating Fe and NiOOH. Because all active species remain as solid phases with extremely low solubility in high-pH media, the electrodes don’t “corrode” in the usual sense of dissolving or pitting; instead, they shuttle between stable oxide/hydroxide states. Alkalinity rapidly passivates iron with adherent Fe(OH)₂/Fe₃O₄ layers, and nickel operates within a potential window where transpassive dissolution is negligible. There are no intercalation hosts to crack, no dendrites to plate, and no flammable SEI to maintain. The KOH electrolyte acts as an ionic conductor and OH⁻ reservoir rather than a reactant, so it can be replaced to restore conductivity if carbonates accumulate from CO₂ ingress. This chemistry underpins NiFe’s legendary tolerance to overcharge, deep discharge, and temperature extremes, translating into decades-long service life.

NiFe chemistry

Flush the electrolyte, recover the capacity !

♻️ NiFe Electrolyte Reconditioning

Turn “end of life” into scheduled maintenance

Nickel-iron batteries regain performance by renewing the electrolyte — not replacing the pack.

  • ♻️ Electrolyte-renewable design: most aging comes from CO₂ converting KOH, not plate degradation.
  • 🔁 Drain, flush, refill: fresh KOH (optionally with LiOH) restores near-new efficiency.
  • 🧪 Clear maintenance triggers: rising internal resistance, slower charging, PH dropping. (< 13).
  • 💧 Rinse & reset: deionized water removes fines & carbonates and reopens conductivity pathways.
  • 🛠️ Long-life serviceability: low-cost, non-toxic, field-doable maintenance that extends decades.

These batteries are also uniquely “renewable” at the electrolyte level: most performance fade stems not from irreversible electrode damage but from CO₂ ingress that converts KOH to potassium carbonate (K₂CO₃), lowering pH, ionic mobility, and charge acceptance while raising internal resistance and gassing. Because the active materials remain solid and insoluble, a full drain/flush and refill with fresh KOH (optionally with a small LiOH additive for low-temperature kinetics) restores the cell’s transport properties and operating window—often recovering near-as-new efficiency. Practically, operators trigger reconditioning when they observe rising IR, sluggish charging, visible carbonate crystals, or lab checks showing significant carbonate fraction by simple two-endpoint titration (separating OH⁻ from CO₃²⁻). Rinsing plates and separators with deionized water removes carbonates, iron fines, and carbonated gel, reopening pores and wetting paths; the new electrolyte then re-establishes high conductivity without altering electrode stoichiometry. Benefits are compelling for off-grid users: service can be done in the field with basic PPE and containers, it’s low-cost and non-toxic relative to replacing a pack, and it resets calendar life without dependence on electronics or proprietary firmware. In effect, NiFe turns “end of life” into scheduled maintenance—swapping the electrolyte when carbonate accumulation becomes performance-limiting, and keeping the same rugged plates working for decades.

Nickel Iron battery specifications

High quality Edison cells made in Europe

For several years, we sourced Chinese-manufactured Edison cells due to their strong availability and competitive cost-to-value ratio. More recently, however, we have transitioned to a European-based manufacturer for strategic and quality-driven reasons:

  • Uncompromising quality assurance — ISO-certified production with individual cell testing and traceability before dispatch.

  • European-sourced raw materials — steel, nickel, iron powders, and consumables sourced within the EU whenever possible, ensuring supply chain transparency and higher consistency.

  • Exceptional logistics and delivery speed — only 3 days from factory to our facility, enabling rapid order fulfillment before onward shipping to the US and Canada through our logistics partner.

  • Superior performance characteristics — flatter and more predictable discharge curves, supporting higher discharge rates (up to 1C) and tolerance to power bursts from inverters without voltage sag or collapse.

Edison cells voltage curve

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