Outdoor Battery Containment System Engineered for Fail-Safe Monitoring

Automated Dunk Tank and Outdoor Storage Solutions for Preventing Thermal Runaway

Discover how ACS engineered a fail-safe battery containment and storage system for a major EV development center. By prioritizing automotive industry safety, this custom dual-unit solution combines continuous hazard monitoring with automated submersion technology, effectively preventing thermal runaway and protecting R&D facilities during high-risk electric vehicle battery testing.

The Challenge

A global automotive manufacturer needed a thermal event containment and battery containment storage system at its new electric vehicle development center. Setting new benchmarks for automotive industry safety, the company wanted a dunk tank to contain batteries that were or believed likely to fail, as well as a storage container for any battery packs not in use. The company wanted both units to sit outside the facility’s walls, aimed at preventing thermal runaway risks inside the building.

ACS has worked with the automaker for years, building a track record of proven excellence on past automotive and EV projects. This collaborative history, plus ACS’ demonstrated expertise designing custom battery containment dunk tank systems for others, made it the trusted choice for this project.

The Solution

The automaker wanted both the dunk tank and storage container outside the facility to limit the risk in case of a thermal event, focusing on preventing thermal runaway propagation. Its original plans included separate fire suppression systems for the container and dunk tank, each using different protective measures. Reviewing the designs and working with the authority having jurisdiction, ACS removed the unnecessary complexity while preserving full automotive industry safety requirements.

The ACS team equipped each unit with its own detection system – a gas sensor and heat detector in the storage container and a temperature sensor in the dunk tank – hardwired into the building’s security system to trigger an alert under any fault condition, including power loss or a severed cable, as well as an alarm event. ACS designed the relay logic to fail safe: contacts stay closed during normal operations and open under a fault condition, so building security always receives an actionable signal rather than risking a false all-clear during a system failure.

ACS adapted its proven baseline battery containment dunk tank design, which uses a hydraulic lift platform to submerge the battery, with several unique features reflecting the project requirements:

• The tank supports two operational modes: battery in known failure and battery suspected of failing. Once a failing battery is loaded onto the tank platform, the operator initiates submersion from a touchscreen HMI. Batteries at risk of failing are placed on the platform and monitored by sensors for a rapid increase in temperature, effectively preventing thermal runaway by triggering the PLC to lower the platform into the brine solution.
• Brine solution was selected because it cools the battery and aids its electrical discharge, eliminating the need to insulate the tank. Because the solution evaporates in the outdoor tank, sensors monitor brine levels, so operators know when to refill the tank.
• An insulated upper chamber around the platform seals the dunk tank, protecting it from the elements and slows evaporation of the brine solution.

The Outcome

The outdoor dunk tank and battery storage container work together to reduce the automaker’s risk of fire or uncontrolled chemical release, strengthening its electric battery testing program and advancing automotive industry safety. Continuous monitoring of both units through the network of integrated sensors ensures the right people get real-time alerts, even after hours, while on-site operators can monitor status through the touchscreen HMI.

With the dunk tank’s two operating modes, the manufacturer avoids unnecessary damage to functional batteries. The watch mode lets operators separate and safely monitor a battery at risk, but only submerges the battery if it starts to fail. Both units were designed to hold the automaker’s largest battery configuration and easily scale, without requiring redesign, as the automaker’s electric battery program grows.

Key Features

• Outdoor battery storage container and dunk tank have safety sensors integrated with facility’s security system for fail-safe, real-time alerts
• UL 508A-listed control panel houses the
• Dunk tank operates with two modes: manual submersion for failing batteries and sensor-triggered submersion for batteries at risk of failure
• Brine solution used to cool battery and aid electrical discharge, eliminating need to insulate the dunk tank.
• Sensors monitor brine levels to alert when additional solution is required
• Insulated upper chamber protects the dunk tank from the elements and slows brine evaporation
• Storage container (roughly 142” W x 141” H x 103” D) holds up to 8 batteries

ACS Services

• Equipment design and engineering
• Equipment manufacturing
• Control system and safety integration
• Electrical panel design and packaging
• Site acceptance testing and commissioning support