The FutureTech Auto Blog

Hybrid, Plug-In, and Electric vehicle technologies have implemented a multitude of battery technologies into a significant number of vehicle platforms.  From 2000 – 2010 Nickel Metal Hydride (NiMH) dominated hybrid vehicles and it continues to dominate the hybrid market today.  However, in 2009 Lithium technology began to make its mark in the hybrid market and this technology has continued to move steadily into the hybrid market with each passing model year.  Plug-In and full electric hybrids have been predominantly Lithium technology from the very beginning and these vehicles have been strictly Lithium for many model years. 

Every technology has iterations during its life cycle.  The frequency of these iterations becomes less frequent as the technology matures.  Battery technology is not maturing, but, it is iterating quickly due to the rapid cell technology changes.  When applying these changes to the repair industry where vehicles must be - it has a profound effect on the technicians that must perform the data analysis, diagnostics, and repair.  Unlike traditional vehicles that are far more mature and can be repaired by using pattern failure (pattern failure symptom recognition) analysis for a given vehicle manufacturer and model, advanced technology vehicles with electric drives and battery packs cannot be diagnosed using pattern failure recognition.  With changes in battery cell chemistry, sometimes by model year, pattern failure recognition is impossible.  Furthermore, when cell chemistries change, this means that the data and how it will react with various driving conditions is very different from year to year – even for the same vehicle model.
​
To solve this dilemma, service technicians and their managers need to recognize that the necessary analysis and diagnostic treatment for the advanced technology vehicles is significantly different than a traditional vehicle.  Technicians will need to accept that they will need to learn the operation of the different battery technologies so they can determine how to interpret scan tool data and how to manipulate the vehicle system to force the diagnostic process into something less gray and more binary.  So, it’s time for technicians to go back to school; the train has already left the station.   

​Many times during a FutureTech hybrid training class, we’re asked by students if there is any easy method of determining whether a driveability problem is engine related or electric propulsion related.  Depending on which manufacturer and systems design this can be more or less difficult to determine.  However, there is one generic method of at least isolating whether the problem is engine or electric propulsion related and that is to use the Regenerative (Regen) Braking mode. As a short review, Regen converts the kinetic energy stored by the vehicle (in motion) into electricity by the 3-phase electric drive motor.  This converted energy is then transferred to the 3-phase power inverter and rectified using software controls from alternating current to direct current.  This direct current is transferred to the battery pack to store the energy.
 
To determine whether a hesitation, chuggle, fish bite, or other low power condition is engine or electric propulsion related, merely accelerate the vehicle at wide-open throttle for about 5-10 seconds.  You will likely feel the problem during this acceleration.  After the 5-10 second acceleration, immediately perform an aggressive braking event.  If you can still feel the problem during Regen braking, it’s a problem related to the electric propulsion system (drive motor or power inverter).  If the problem is no longer there during Regen, the problem resides in the traditional engine system.  I want to stress here that, this is a simple generic test to help narrow where the problem may be stemming, it is not meant to be an “all encompassing” test.  Notice that I didn’t mention the battery pack.  There is a separate test that can be performed on the battery pack (stress test), and this can be performed during the same test drive for the engine and electric propulsion system by using a scan tool.  The battery pack can also cause hesitations, chuggles, fish bites, etc.
 
In total, this is about a 20 minute test drive for the engine, electric propulsion, and battery pack.  It’s simple, effective, and will save a technician significant diagnostic time.