Nilar reoxygenating battery strings


Nilar batteries are connected as strings in series of 2-5 battery packs to fit customer system voltage. The battery strings are controlled by Nilar BMS for verification of specified performance. The bi-polar battery design enables high power charge/discharge and the Nilar Hydride® (NiMH) battery chemistry provides not only non-flammable water-based electrolyte but also long calendric lifetime. Add to it our patented reoxygenating technology and we now provide customers with high cycle life strings delivering from 2.4 to 6 kWh.



  • Nilar Hydride® bi-polar design enables us to offer safe and sustainable batteries, providing long term power for energy storage solutions.
  • Nilar batteries have a sealed design with no emissions of gases or electrolyte during its service life.
  • Nilar batteries are easy to transport and aren’t affected by any costly or complicated transport regulations.
  • Nilar batteries contains none of the regulated heavy metals mercury, cadmium and lead. The design has been developed to enable a cost efficient recycling process and a high degree of reusable materials.

Battery Pack Features

Nominal voltage
The cell voltage of a battery cell is governed by the electrochemical potentials of the active materials used in the negative and positive electrodes and the electrolyte. For the hydride system used in Nilar battery packs, the nominal cell voltage is 1.2 V. The Nilar 12 V module is comprised of 10 cells connected in series within the module, achieving a nominal module voltage of 12 V. The nominal voltage of Nilar battery packs is determined by the number of 12 V modules connected in series within the battery pack. Battery packs are connected in series to match the required system voltage, forming a string. The nominal voltage of a string equals the number of battery packs multiplied by the nominal battery pack voltage.

Rated capacity
The battery capacity is rated in ampere-hours (Ah) and denotes the quantity of electricity a fully charged battery can deliver at a 5 h discharge to 1 V per cell at +20°C. Nilar battery packs are made with a number of 12 V modules connected in series to achieve the battery pack capacity of 10 Ah. To meet the required capacity of a Nilar battery installation, the battery packs, or battery strings, are connected in parallel. The total battery capacity is given in multiples of 10 Ah.

Operating voltage
Typical cell operational voltage is minimum 1,1 V per cell at discharge to maximum 1,6 V during charge. This corresponds to a 11 – 16 V range for the module.

Operating temperatures
For optimal performance the recommended battery room temperature is +20°C.

Intermediate state-of-charge
Batteries can be stored or operated at an intermediate state-of-charge (SOC) without loss of performance.

The Nilar battery is a stable electrochemical system. The design mitigates corrosion to prevent premature and unpredictable end of life. The design is virtually shock and vibration resistant. Testing shows a graceful decline in performance over the life of the pack.

The Battery Design

The bi-polar design enables Nilar to produce modular batteries with improved volumetric power density and simplified battery construction. The main advantage of the bi-polar design utilized by Nilar is the common and shared large area current collector. This important feature reduces the volumetric overhead and inherently results in uniform current flow across the cell. Uniform current and resistance paths promote uniform heat gradients over the electrodes. A uniform battery temperature promotes a uniform electrochemical aging of the electrodes in the modules, which translates into a long service life.

Nilar battery packs are optimized for installation in energy storage systems, whether it be for a home, business or infrastructure projects. An Integrated Monitoring Unit is integrated on the battery packs together with industrial connectors for electrical and communication interfaces. The electronic battery management system, communication bus and the battery packs are designed to fulfill requirements for electrical safety in battery systems with a nominal voltage up to 600V.

Expanded view of reoxygenating battery pack.

Pack design

The pack designs achieves a compact assembly of cells and other components required in a battery pack to meet required system voltage and run-time. They are assembled into a pack by a pick-and-place manufacturing process, followed by electrolyte filling and formation using a few charge/discharge cycles to activate the electrochemical system in the cells.

There is one end-piece on each side of the battery packs. Together, with the steel bands, the end-pieces provide uniform cell compression over the electrode surfaces, impact protection to the cell stack, and electrical insulation from the pack potential.

The end-pieces also serve as a support structure for the Integrated Monitoring Unit mounted on one of the endpieces of the Energy and Energy+ battery packs.

Integrated Monitoring Unit
The Integrated Monitoring Unit (IMU) is an electronic monitoring system, enclosed in a case and attached to the battery pack end-piece. The IMU monitors the conditions of the battery pack and communicates the measured data to the BMS.

Pressure sensor
The integrated pressure sensor enables recording of battery pack pressure. This signal is used for battery pack diagnostics and for high precision charge management. The risk of venting by overcharging the battery pack is eliminated by this unique feature.

Rupture disc
Nilar battery packs are fitted with a rupture disc located on the rear side of each battery pack that is activated at a pressure of 7 bar. During normal and mildly abusive conditions, the battery pack is sealed with no emission of gases or electrolyte. In normal operation, the internal pressure of Nilar battery packs is below the activation pressure of the rupture disc.

The 12 V module is the building block for all Nilar batteries. The 10 cells are connected in series to create modules with a nominal voltage of 12 V.

Contact plate
The contact plate electrically connects the adjacent modules in the pack and thus eliminates the need for external connectors between modules.

Heat dissipation
The patented design has the heat conducting from the contact plates to the long side surface of the 12 V module, where stacked modules increase the effective surface area for air cooling.