Hybrid vehicles and electric vehicles (HEV or EV) have two main things in common, electric motor-generators (MG) and a battery pack. The battery pack, in both cases, is like the fuel tank in a conventional vehicle, storing energy to power the MG and vehicle electrical systems. Unlike the fuel tank in a conventional or hybrid vehicle, however, the battery pack can also be recharged by the car itself, via the MGs.
At their most basic level, electric vehicle and hybrid vehicle battery packs are a collection of rechargeable cells arranged to hold a specified amount of energy. In this way, they are identical. On the other hand, there are a couple of key differences in chemistry, charging capabilities, and maintenance.
Chemistry and Capacity
The main difference between hybrid vehicle and electric vehicle battery packs is their chemistry. For example, the 2010 Toyota Prius NiMH (nickel-metal hydride) hybrid battery pack holds just 1.3 kWh (kilowatt-hours). This is enough to power the MGs for a maximum of a couple of miles stop-and-go traffic in EV-Mode. The 2012 Toyota Prius Plug-In, on the other hand, features a Lithium-ion (Li-ion) hybrid battery, which is about twice as energy-dense as NiMH. Thus, the Prius Plug-In’s 4.4 kWh Li-ion battery pack, at 330 lbs, weighs three times more than the 1.3 kWh NiMH pack in the Prius, yet offers fifteen times more EV-Mode range, up to 15 miles in certain circumstances.
Finally, in electric vehicles whose sole energy source is the battery pack, we see a significant jump in battery capacity. The 2015 Nissan Leaf, for example, is equipped with a 24 kWh Li-ion battery pack, featuring an average range of 84 miles. The Tesla Model S 85 kWh, on the other hand, has a range of about 300 miles. Making the switch to Lithium-ion rechargeable battery chemistry makes this possible, because NiMH or SLA (sealed lead acid) batteries would be too heavy.
The other main difference between hybrid vehicle and electric vehicle battery packs is how they are charged. Hybrid vehicles, such as the Toyota Prius and Ford Fusion Hybrid, do not feature a charge port for the hybrid battery. Instead, they are charged by the MGs, driven by the ICE or during regenerative braking. Plug-in hybrid vehicles, on the other hand, feature a charge port for their small hybrid battery packs. The Prius Plug-In, for example, takes about 90 minutes to charge on an LII (Level 2, 240 V, 30 A) charging station. Once the 15 miles of EV-Mode capacity is used up, the car reverts to regular hybrid vehicle operation, using a small part of the hybrid battery capacity for improved fuel economy and stop-and-go traffic performance.
Electric vehicle battery packs, which have the largest battery capacity, can only be charged by electric vehicle charging stations and, to a lesser degree, regenerative braking. The Nissan Leaf’s 24 kWh battery pack, for example, takes about four hours on an LII charging station, or as little as thirty minutes on an LIII (Level 3, 480 V, 3 Φ, 125 A) charging station. On an LIII charging station, Tesla Model S 85 kWh can fully charge in about an hour.