MDL Begins Development of Indigenous Lithium-Ion Battery System for Project-75(I) Submarines

India’s submarine manufacturing ecosystem is moving towards advanced energy storage technology, with Mazagon Dock Shipbuilders Limited (MDL) initiating efforts to develop an indigenous Lithium-Ion Battery (LIB) System with Battery Management System (BMS) for the Indian Navy’s Project-75(I) submarines.

MDL, a Government of India defence public sector undertaking under the Ministry of Defence, issued an Expression of Interest (EoI) in July 2026 to identify capable Indian companies for the design, development and supply of the advanced battery system. The initiative aims to create a domestic capability for a strategically important submarine technology.

Indigenous Battery System Planned for Six Project-75(I) Submarines

The MDL initiative seeks industry participation for developing lithium-ion battery systems for the six Project-75(I) submarines planned to be constructed in India.

The proposed system is expected to have a capacity of approximately 20.64 MWh with a rated voltage range of around 740–800 VDC. The development scope includes battery cell technology, module design, battery pack integration, Battery Management System development, thermal management solutions, prototype qualification and supply of production-standard systems.

The programme represents an important step towards developing indigenous capability in submarine energy storage, a critical technology that directly influences underwater endurance and operational performance.

Lithium-Ion Batteries to Improve Submarine Underwater Endurance

Submarine batteries provide the stored electrical power required for silent underwater operations. Their performance influences how long a conventional submarine can remain submerged, maintain stealth and conduct missions without surfacing.

Lithium-ion battery technology offers higher energy density, faster charging capability and improved power availability compared with traditional lead-acid batteries. These advantages can enhance the operational flexibility of conventional submarines by allowing longer submerged endurance and more efficient power management.

For Project-75(I), an advanced battery system will complement other planned capabilities, including Air Independent Propulsion (AIP), modern sensors, weapon systems and integrated combat management systems.

MDL Focuses on Complete Indigenous Battery Ecosystem

The MDL requirement covers more than battery supply and focuses on developing a complete submarine-grade energy storage ecosystem within India.

The proposed development includes:

• Lithium-ion battery cells and modules
• Battery pack architecture and integration
• Indigenous Battery Management System
• Thermal management and safety systems
• Prototype testing and qualification
• Production-series battery systems

The Expression of Interest specifies Lithium Iron Phosphate (LFP) chemistry and requires indigenous manufacturing of battery cells in India. The requirement also includes provisions related to secure sourcing and compliance with defence procurement regulations.

Strengthening India’s Project-75(I) Submarine Manufacturing Capability

Project-75(I) is one of India’s major submarine modernisation programmes and aims to construct six advanced conventional submarines through domestic shipbuilding capabilities.

MDL is expected to play a central role in the programme, combining domestic shipbuilding expertise with international technology cooperation. Developing an indigenous lithium-ion battery system adds another layer of self-reliance by targeting a critical subsystem that directly impacts submarine performance.

The initiative can also create opportunities for Indian companies working in advanced materials, energy storage, electronics, power management and defence manufacturing.

Indigenous Battery Technology Supports Future Naval Platforms

Energy storage systems are becoming increasingly important across modern defence platforms, including submarines, unmanned systems and electrically powered military equipment.

The development of submarine-grade lithium-ion batteries through Indian industry participation represents a significant advancement in defence technology self-reliance. It strengthens India’s ability to design, build and maintain complex underwater platforms with greater domestic control over critical systems.

With indigenous shipbuilding, advanced propulsion technologies, locally developed combat systems and domestic energy storage solutions, India is building a stronger foundation for future naval capabilities.

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References

• Mazagon Dock Shipbuilders Limited (MDL) — Expression of Interest for Design, Development and Supply of Lithium-Ion Battery System along with Battery Management System for Project-75(I) Submarines
• Ministry of Defence, Government of India — Project-75(I) submarine programme and Strategic Partnership model
• Indian Navy — Submarine modernisation and indigenous technology development initiatives
• Defence Research and Development Organisation (DRDO) — Indigenous naval technology programmes
• Mazagon Dock Shipbuilders Limited — Submarine construction and defence shipbuilding programmes

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