The Ministry of New and Renewable Energy (MNRE) has issued draft guidelines for series approval of storage batteries for compulsory registration with the Bureau of Indian Standards (BIS) under the Solar Systems, Devices and Component Goods Order 2025.

The guidelines aim to facilitate manufacturers and test laboratories in developing a series of products for approving product families. The framework applies to lead-acid batteries, lithium-ion batteries for portable and industrial applications, as well as nickel-based batteries.

The reference standard for testing, sampling, and pass criteria is IS 16270:2023, which covers secondary cells and batteries for solar applications, general requirements, and testing methods.

Definition and Scope

The guidelines define a product family as the maximum configuration of components and sub-assemblies, along with a description of how the models are constructed from this maximum configuration.

Products in a family must have common design, construction, parts, or assemblies that ensure conformity with the applicable requirements. The concept aims to enable manufacturers to categorize products into families for enhanced efficiency in testing and approvals, avoiding duplication across similar models.

Material and Construction Requirements

The draft guidelines provide chemistry-specific construction requirements. For lead-acid batteries, containers for vented types may be made of hard rubber, transparent styrene acrylonitrile (SAN), fiber-reinforced plastic, or polypropylene.

Sealed batteries may use polypropylene copolymer, acrylonitrile butadiene styrene, SAN, or any other acid-resistant plastic. Materials such as sulphuric acid, water, separators, and containers must conform to IS 16270.

Nickel-cadmium and nickel-metal hydride batteries require high-strength, alkali-resistant containers, such as nickel-plated mild steel, stainless steel, or non-porous plastic. The electrolytes must use potassium hydroxide with distilled water, supplemented with lithium hydroxide additives if specified by the manufacturer.

Separators must be alkali-resistant and insulating. Lithium-ion batteries must utilize high-quality raw materials, with casings designed for cylindrical, prismatic, or pouch formats. Pack enclosures must be flame-retardant and impact-resistant, and materials should conform to national or international safety standards.

Testing Procedure

The guidelines state that batteries for testing will be picked at random from a batch by the test laboratory. Manufacturers must provide technical details, such as the container material, type of separator used, type of sealing for sealed batteries, and overall dimensions.

Vented lead-acid batteries must be supplied with suitable level indicators for opaque containers and electrolyte level markings for transparent ones, in addition to connectors. Manufacturers must also provide recommendations for charging procedures in the laboratory.

Operating conditions must follow the manufacturer’s recommendations on temperature and humidity.

Sampling and Testing

The number of samples to be taken and testing sequences are governed by IS 16270 Clause 8.4.1, ensuring that all cells and batteries in a batch share identical nominal voltage, rated capacity, electrolyte composition, and overall dimensions.

The guideline outlines separate provisions for various categories, including stationary lead-acid batteries (vented and valve-regulated types), tubular gel valve-regulated lead-acid (VRLA) batteries, vented nickel-cadmium cells, nickel-cadmium prismatic rechargeable single cells with partial gas recombination, portable nickel-cadmium and nickel-metal hydride batteries, and lithium-ion cells and batteries for portable and industrial applications.

The guidelines specify marking requirements across all chemistries and types, mandating details such as source of manufacture, ampere-hour capacity, voltage, date and year of manufacture, country of origin, polarity, and cell designation. Markings must be durable and non-deteriorating.

For lithium-ion cells, manufacturers must additionally disclose the type and material of the container, the chemistry or technology, the separator material, the overall dimensions and weight, and the rated voltage and capacity.

Series Classification

The guidelines set out detailed series classifications to streamline type testing. For example, 2 V flooded lead-acid cells are grouped into series, ranging from up to 400 Amp-hours (Ah), between 400 Ah and 700 Ah, 700 Ah to 1,000 Ah, and above 1,000 Ah, with representative models required to be the highest rating in the series.

Similar classification structures are provided for VRLA lead-acid batteries, 12 V lead-acid batteries, nickel-cadmium, nickel-metal hydride, and lithium-ion batteries, including cylindrical, prismatic, and pouch cells. Lithium-ion batteries are categorized into series, ranging from up to 20 Ah to above 1,000 Ah.

Representative models undergo type tests as per IS 16270 Table 6. Short-term tests, such as capacity tests, must be performed across all ratings in a series; failures will require resubmission.

Endurance and type tests will be performed on the highest rated capacity sample, and successful qualification allows the report to cover all models in the series. Manufacturers are required to submit undertakings that no changes have been made to grid alloy composition, purity, thickness, electrode ingredients or preparation, or manufacturing quality systems across models included in a series.

Safety and Handling Requirements

The guidelines include detailed safety obligations for manufacturers and suppliers of batteries for photovoltaic applications. Batteries pose risks of fire, explosion, and chemical or electrical hazards.

Manufacturers must specify suitable lifting devices for heavy batteries, maintain battery temperatures as recommended, and ensure that terminals, screws, clamps, and cables are free of corrosion and damage.

They must declare whether the system supports capacity expansion and provide information on potential electric shock hazards. Installations must follow the safety data sheet for the chemistry used, and upper DC voltage limits must be disclosed for domestic and non-domestic systems.

Exposed components must be insulated and protected, and parallel battery systems must include isolators. Manufacturers must develop safe work procedures for handling chemical hazards such as damaged casings or electrolyte spillage.

Safety equipment such as acid-resistant gloves, aprons, goggles, bicarbonate of soda for acid spills, and boric acid for alkaline electrolyte spills must be specified. Instruction brochures must include the following information: electrical characteristics, charging conditions, size, weight, terminal type, operating life, and storage period.

Storage must be maintained in dry, well-ventilated conditions, avoiding dampness, combustible materials, and heat sources. Recycling and disposal procedures for scrapped batteries must also be specified.

In June this year, MNRE issued draft safety guidelines for battery energy storage systems.

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