Nickel Metal Hydride (NiMH) Hybrid battery Systems

Course ID: AODNIMH005 

Recommended Prerequisites:

High Voltage Safety and PPE (#AODHVS010)

High Voltage Vehicle Safety Systems (#AODHVVSS001)



InstructorDr .Mark Quarto

Course Length: 5 modules (each containing approximately 1 hour of instruction)

Course Handbooks Included: 1 digital copy per module

Learning Assessments: Post-module assessments with certificate of completion


This course series is a MUST for any technician that is servicing hybrid vehicles.  NiMH battery systems continue to be the primary battery technology in hybrid vehicles and have been since the 2000 model year.  If a technician doesn’t know the fundamentals of NiMH operation it is impossible for them to provide the customer a solid diagnosis or repair.  This course will concentrate on the NiMH technology, how it performs as it ages, how it can effect vehicle performance and fuel economy, and how to test it by using a Scan Tool. 

Course Objectives

By participating in this On Demand Course, you will be able to:

  • List the different formats of a NiMH cell or module and explain the advantages and limitations of NiMH technology
  • Explain the functions of Battery Power and Battery Energy
  • Explain what major sensing and component control systems operate in conjunction with the battery controller system
  • Using the NiMH Module Voltage Sensing Circuit, describe how this circuit functions to communicate battery module/cell voltages to the battery controller
  • Describe the operation of a battery module/cell temperature sensing circuit
  • Describe the purpose and operation of battery pack contactors, the battery pack Pre-Charge circuit and the battery pack Current Sensor
  • Describe NiMH cell aging and the Apparent Capacity Loss function
  • Elaborate on how geographical area, terrain, and drive cycle can affect the operation of a NiMH battery pack (cell)
  • Visually identify battery module or cell electrolyte leaks and bus bar corrosion
  • Explain how a battery pack controller aging can affect how voltages can be skewed
  • Describe how a battery pack cooling system can effect battery module/cell longevity, premature module/cell failure, and overall performance
  • Explain the battery pack Stress Test process and how the results can help determine what actions need to be taken

Course Outline

Part 1:  NiMH Batteries: Cell Construction and Operation

  • Hybrid Vehicle Power Model & NiMH Batteries
  • Pros and Cons of NiMH Technology and Comparison to Lithium Technology
  • Cylindrical and Prismatic Battery Cells
  • Battery Ratings
  • Power vs. Energy Batteries


Part 2:  NiMH Product Systems: Ford, GM, Honda, Lexus, Nissan, and Toyota Batteries

  • Battery Pack Hardware Review
  • Battery Pack Controller Sensing Systems
  • Battery Bus Bar Cell Connecting Systems
  • Battery High Voltage Contactor Systems
  • Battery Pre-Charge System


Part 3:  NiMH: Vehicle Performance Changes Due to NiMH Aging

  • Cell Aging….and How it Effects Vehicle Performance
  • Geographic Effects on Cell Aging
  • Battery Cooling Systems…and How It Effects Cell Aging
  • Cell Chemical State Changes and Effects on Capacity (i.e. Memory Effect)
  • Servicing Aged Cells/Modules


Part 4:  Failure Modes and What Causes Cell Aging or Loss of Capacity

  • Cell Electrolyte Leakage
  • Bus Bar Corrosion
  • Controller Electronics Aging or Failure
  • Solutions for servicing NiMH


Part 5:  How to Test and Diagnose NiMH Hybrid Battery Packs Using the Scan Tool

  • Controller Sensing
  • Stress Testing – Power & Capacity
  • Stress Testing with Scan Tool
  • Stress Test Process

At the conclusion of this series, the technician will be able to identify the condition of a battery pack, servicing instead of replacing it, and using specific testing methods outlined in this course.


Is this online training course for you?

NiMH battery systems continue to be used in Hybrid Electric Vehicle (HEV) applications and provide an excellent foundation in high voltage battery pack systems.  This course will include NiMH battery cell operation, cell/module failure modes, diagnostic testing methods, battery hardware components, battery stress testing techniques – and how some of these areas differ from Lithium systems.  This course provides automotive service professionals with limited or some experiences in high voltage battery pack systems an excellent foundation to learn these battery pack systems and use this information as platform to learn high voltage Lithium battery pack systems.  There are also areas within the course that could benefit more seasoned battery pack professionals.


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