Hybrid High Voltage Components
The three major components of a hybrid system include the electric motor/ generator, the high voltage wiring and the high voltage Ni-Mh battery pack.
The electric motor can assist in propulsion of the vehicle and recharges the batteries depending on the mode it is in. The batteries are recharged either using power from the gasoline engine or through regenerative braking, a process whereby the energy typically wasted during the braking process is used to drive the electric motor in its charging mode.
High voltage electrical cables, which conduct the power from the battery to the electric motors and back, can be found in the engine compartment, on the underside of the vehicle and the area where the battery is stored.
The High-Voltage NiMH battery modules can range from 144v to 330v DC. A number of single HV cells are arranged into a “stick”, several of these sticks are combined to make a battery module (figure 20 – picture courtesy of Honda). Each individual cell is roughly the size of a “D” cell battery.
The Prius as well as many other hybrid models utilize a battery stack consisting of 38 prismatic NiMH modules connected in series. These are a series of flat battery cells “sandwiched” together. (figure 21).
All of these NiMH batteries are considered a “dry cell” and do not present a significant spill hazard. The electrolyte, consisting of Potassium and Sodium Hydroxide, is absorbed into the cell plates to form a gel that will not normally leak, even after a collision. If the battery is crushed, however, it is possible for a small amount of electrolyte (drops) to leak. The industry is currently looking towards utilizing lithium ion and other battery technologies to improve the efficiency of the system.
High voltage batteries are typically located behind the rear seat in the sedan models (figure 22) , under the rear seat or rear cargo area in the SUV models (figure 23) . All hybrid models also utilize a (12v) battery system to power low voltage vehicle systems that can be found in a normal vehicle.
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By: Jason Emery
Emergency Training Solutions, LLC
