An Easy Method to Determine Whether a Driveability Problem is the Engine, Electric Propulsion or Battery Pack System
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.
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