Hybrid Cars, Hybrid Trucks, Hybrid Vans and Hybrid Motorcycles

This article is about hybrid car batteries. First, some definitions are provided. Second, hybrid battery costs are discussed. Third, charge capacity and hybrid battery life are explained. Lastly, battery cost is discussed.

Any kind of rechargeable battery stores electricity through chemical means, and batteries have a number of important constraints on them, especially for hybrid cars and pure electric vehicles . To make this discussion make sense, we’re going to have to define some terms.

The first term is energy density . One reason why gasoline is such a useful fuel is that it’s very dense in terms of the energy carried per unit mass and unit volume. For example, gasoline has nearly 20x the energy density of liquid hydrogen per unit of volume, and is nearly 60% greater in terms of its energy density than ethanol or methanol.

Most electrical batteries can’t come close to the energy density of a good alcohol based engine. The handful that can (generally zinc oxide/silver batteries) are prohibitively expensive. This is one reason why, if you look at a Prius, almost a third of the weight of the vehicle is the batteries .

Hybrid battery costs drive a lot of the price premium for a hybrid vehicle (especially hybrid trucks ) . There are three broad categories of batteries suitable for use in a high energy application. Nickel-Metal Hydride (an evolved form of the Nickel Cadmium rechargeable battery), Lithium Ion, and Zinc/Silver.

Nickel-Metal/NiCad batteries are the cheapest to install, and have the lowest energy density of the set; they are also fairly heavy, and carry heavy metals (nickel and cadmium) making their disposal problematic and expensive.

Lithium Ion batteries have roughly 50% greater energy density compared to Nickel Metal Hydride, and nearly 40% greater than straight NiCad. They are also roughly 3 to 4x as expensive per watt/hour stored, because of the high price of Lithium. Unlike NiMH batteries, they also run into problems with waste heat when discharging. (One of the great technical challenges for an all-electric vehicle is getting enough energy stored in the batteries – and safely out again – without the batteries overheating.)

Zinc/Silver batteries have nearly 30% greater energy density than Lithium Ion batteries, but are prohibitively expensive, and use two resources (Zinc and Silver) that are in short supply. The primary use for Zinc/Silver batteries is in the military where they’re used to power guidance systems for torpedoes and missiles.

Most hybrids use NiCad or NiMH batteries ; a very few are making the transition to Lithium Ion batteries, and most aftermarket conversion kits use Lithium Ion batteries – the theory being that anyone who’ll void the warranty on their car will pay the premium for the higher energy density. The Tesla Roadster , the only pure plug-in car on the market, uses banks of Lithium Ion batteries; these contribute nearly $70,000 towards the car’s $110,000 asking price. The Chevy Volt uses NiMH batteries to keep costs down, but uses a lot of them – the Volt’s batteries replace a lot of the weight and volume used for the transmission in the car.

When will the pure plug in vehicle become affordable? It may not happen any time soon. The constraints of battery cost, waste heat dissipation and weight mean that a car that acts like a car, with passenger space and cargo space, would, as a pure electric vehicle, have a cruising range of 40 to 60 miles between charges, and while that’s useful for most American drivers, it’s not quite enough to replace a gasoline car that can get over 300 miles on one tank full of gas.