---
kind: "range"
citation: "49 C.F.R. §§ 561.7–561.10"
title: "49"
from: "561.7"
to: "561.10"
count: 4
url: "https://uscodex.org/cfr/49/561.7..561.10"
---

# §561.7. Documentation for low temperature operation safety.


At NHTSA's request, each manufacturer shall submit documentation that includes the following:

- (a) The make, model, model year, and production dates of the vehicles to which the submitted documentation applies.
- (b) **The lower temperature boundary for safe REESS operation in all vehicle operating modes.**
- (c) A description and explanation of charge and discharge rates at the manufacturer specified lower temperature boundary for safe REESS operation.
- (d) **A description of the method used to detect REESS temperature.**
- (e) A system diagram with key components and subsystems involved in maintaining safe REESS charging and discharging operation for temperatures at or below the manufacturer specified lower temperature boundary for safe REESS operation.
- (f) A description of how the vehicle controls, ancillary equipment, and design features were validated and verified for maintaining safe REESS operations at or below the manufacturer specified lower temperature boundary for safe REESS operation.
- (g) **Overall evaluation—** A description of the final manufacturer review/audit process and results of any final review or audit evaluating the technical content and the completeness and verity of [paragraphs (a) through (f)](#a..f) of this section.

# §561.8. Documentation of a visual warning for malfunction of vehicle controls that manage REESS operation.


At NHTSA's request, each manufacturer shall submit documentation that includes the following:

- (a) The make, model, model year, and production dates of the vehicles to which the submitted documentation applies.
- (b) **A system diagram that identifies all the vehicle controls that manage REESS operation.** The diagram must identify what components are used to generate a visual warning indicating malfunction of vehicle controls to conduct one or more basic REESS operations.
- (c) A written explanation describing the basic operation of the vehicle controls that manage REESS operation. The explanation must identify the components of the vehicle control system, provide description of their functions and capability to manage the REESS, and provide a logic diagram and description of conditions that would lead to triggering the telltale activation.
- (d) Validation results from tests to confirm the display of a visual warning in the presence of a malfunction of the vehicle controls which manage safe operation of the REESS.
- (e) **Overall evaluation—** A description of the final manufacturer review/audit process and results of the final review or audit which evaluated the technical content and the completeness and verity of [paragraphs (a) through (d)](#a..d) of this section.

# §561.9. Documentation of an audio-visual warning for a thermal event in the REESS.


At NHTSA's request, each manufacturer shall submit documentation that includes the following:

- (a) The make, model, model year, and production dates of the vehicles to which the submitted documentation applies.
- (b) **A system diagram of the thermal event warning system.**
- (c) **A written explanation describing the basic operation of the thermal event warning system.** The explanation must identify the components of the thermal event warning system, provide descriptions of their functions and capability, and provide a logic diagram and description of conditions that would lead to triggering the warning activation.
- (d) Validation results from tests to confirm the activation of an audio-visual warning in the case of a thermal event in the REESS.
- (e) **Overall evaluation—** A description of the final manufacturer review/audit process and results of the final review or audit which evaluated the technical content and the completeness and verity of [paragraphs (a) through (d)](#a..d) of this section.

# §561.10. Documentation for single cell thermal runaway and propagation safety risk mitigation.


The vehicle manufacturer shall make available to NHTSA, upon request, documentation demonstrating how the vehicle and its REESS are designed to mitigate the safety risks associated with thermal propagation resulting from a single cell thermal runaway due to an internal short within the cell. The documentation shall demonstrate thermal propagation safety risk mitigation for the vehicle in external charging mode, active driving possible mode, and parking mode. The documentation shall include the following:

- (a) **Vehicle information.** This part of the documentation shall identify the make, model, model year, and production dates of the vehicles to which the submitted documentation applies.
- (b) **Part I: System analysis.** This part of the documentation shall identify the conditions which could lead to single-cell thermal runaway due to an internal short-circuit in different vehicle operational modes and allocate applicable functional units, components, and subsystems to each identified condition. This part shall include:
  - (1) A system diagram and a description of all relevant physical systems and components of the REESS, including information about the cell type and electrical configuration, cell chemistry, electrical capacity, voltage, current limits during charging and discharging, and thermal limits of the components that are critical for thermal propagation safety.
  - (2) A system diagram, operational description of sensors, components, functional units relevant to single-cell thermal runaway due to internal short-circuit and thermal propagation, and the interrelationship among the identified sensors, components, and functional units;
  - (3) A description of conditions under which a single-cell thermal runaway and propagation event due to an internal short-circuit could occur;
  - (4) A description of how the identified conditions were allocated to each identified component, functional unit, and subsystem;
  - (5) A description of the process used to review the identified conditions and their allocation to the identified sensors, components, and functional units, for completeness and validity; and
  - (6) A description of the warning or notification system before the thermal runaway occurs, including a description of the detection technology and mitigation strategies, if any.
- (c) **Part II: Safety risk assessment and mitigation process.** This part of the documentation shall identify thermal propagation safety risk mitigation strategies for identified conditions leading to single cell thermal runaway in Part I and include:
  - (1) A description of the safety risks and safety risk mitigation strategies, and how these were identified, and
  - (2) A description of how each risk mitigation strategy manages, mitigates, or prevents the identified safety risks.
  - (3) Safety risk mitigation strategies identified should include those that mitigate the risk of single cell thermal runaway due to an internal short and mitigate the occurrence of thermal propagation due to single-cell thermal runaway resulting from an internal short-circuit within the cell.
- (d) **Part III: Verification and validation of risk mitigation strategies.** This part of the documentation pertains to verification that the manufacturer identified safety risks and considered safety risk mitigation strategies and shall include:
  - (1) A description of how each risk mitigation strategy was verified and validated for effectiveness,
  - (2) A description of the verification and validation results for each risk mitigation strategy, and
  - (3) **A description of and results from the vehicle level assessment.**
- (e) **Part IV: Overall evaluation of risk mitigation.** This part of the documentation summarizes the vehicle design and manufacturing strategies and their validation to mitigate the safety risks associated with thermal propagation due to single cell thermal runaway resulting from internal short within a cell. This part shall include a description of the final manufacturer review/audit process and results of the final review or audit evaluating the technical content and the completeness and verity of [paragraphs (a) through (d)](#a..d) of this section.