AIS 156: India's EV Battery Safety Standard Explained

What is AIS 156?

AIS 156 is India's Automotive Industry Standard for the safety of lithium-ion traction battery packs and systems used in electric vehicles. Issued by the Automotive Research Association of India (ARAI) under the Ministry of Road Transport and Highways, it defines mandatory safety requirements that every EV battery pack sold in India must meet before receiving CMVR (Central Motor Vehicles Rules) type approval.

In simple terms: if your electric vehicle runs on a lithium-ion battery pack in India, that pack — and the BMS inside it — must be AIS 156 compliant. No type approval means no legal sale.

Which vehicles does AIS 156 apply to?

Vehicle Category	Examples	AIS 156 Applicable?
L1 / L2	Electric bicycles, low-speed 2W	Phase 1
L3 / L4	Electric motorcycles, scooters	Phase 1 & 2
L5	E-rickshaws, cargo 3-wheelers	Phase 1 & 2
M / N (4W)	Electric cars, vans, trucks	Phase 1 & 2

Phase 1 vs Phase 2

Phase 1 (effective March 2022)

Phase 1 focused on foundational safety requirements: overcharge protection, over-discharge protection, short-circuit protection, thermal runaway detection and basic BMS requirements. It established the minimum bar for lithium-ion EV batteries to be sold legally in India.

Phase 2 (effective December 2022)

Phase 2 significantly raised the bar. Key additions included:

• Mandatory vibration and shock testing of the complete battery pack
• Thermal propagation requirements — the pack must not cause external fire within a specified time after internal thermal runaway begins
• Water ingress protection (IP rating requirements)
• Stricter BMS diagnostic and fault communication requirements
• High-voltage contactor-based isolation requirements for higher voltage packs

What AIS 156 requires from a BMS

The standard specifies that the Battery Management System must be capable of:

• Detecting and responding to cell overvoltage (typically >3.65V for LFP, >4.2V for NMC)
• Detecting and responding to cell undervoltage (typically <2.5V for LFP, <2.8V for NMC)
• Detecting overcurrent on both charge and discharge paths
• Detecting short circuit and disconnecting within a defined time window
• Monitoring cell and pack temperature and suspending operation outside safe limits
• Providing fault communication — either via dashboard indicator or a communication bus — to alert the vehicle operator
• Maintaining isolation between the high-voltage bus and the vehicle chassis

How to ensure your BMS is AIS 156 compliant

There are three steps to AIS 156 compliance for a BMS:

1. Design compliance — The BMS must be designed with the correct voltage thresholds, current limits and protection responses for the specific cell chemistry and pack configuration.
2. Pack-level testing — The complete battery pack (cells + BMS + enclosure) must undergo the AIS 156 test battery at an ARAI-approved test lab. The BMS alone cannot be certified — it is the pack that receives approval.
3. Documentation — Test reports, BMS firmware version records, and cell specifications must be maintained and submitted for type approval.

Common compliance mistakes

Lithion Power's team has supported dozens of EV manufacturers through the AIS 156 process. The most common mistakes we see:

• Using a BMS calibrated for NMC cells in an LFP pack — the voltage thresholds will be wrong
• Under-rating the BMS current — a 48V / 60A BMS in a pack that peaks at 80A during acceleration will trigger unnecessary disconnections
• Not validating BMS thermal cutoff temperatures against the test lab's environmental chamber conditions
• Ignoring the communication requirement — Phase 2 requires fault signalling, which a basic non-smart BMS cannot provide for higher vehicle categories