BU-1002: Electric Powertrain, then and now

Explore the limitations of the battery when compared to the internal combustion engine.

Propulsion by an electric powertrain is not new — Ferdinand Porsche designed a hybrid vehicle in 1898. Called the Lohner-Porsche carriage, the hybrid function served as an electrical transmission; its purpose was not to lower fuel consumption as the focus is today. With Mr. Porsche in the driver’s seat, the car broke several speed records in Austria in 1901.

Another early hybrid was the Woods Motor Vehicle built in Chicago in 1915. It had a four-cylinder internal combustion engine (ICE) in conjunction with an electric motor. Below 25km/h (15mph), the electric motor propelled the vehicle; at higher speeds the gasoline engine kicked in to take the vehicle up to 55km/h (35mph).

In early 1900, a car buyer had three choices of propulsion systems: electric, steam, and ICE, of which the ICE was the least common. The electric cars (EVs) appealed to the upper class and they were finished with fancy interiors and expensive materials. Although higher in price than the steam and gasoline-powered vehicles, the EV served the wealthy with its quiet and comfortable ride over the vibrating, smelly and maintenance-prone gasoline-powered counterpart. Best of all, the EV did not require changing gears. Back then, the knuckle-busting chore of shifting gears was the most dreaded task when driving a gasoline-powered car. Nor did the EV need manual cranking to start the engine, a task the upper class did not want to be seen doing. Since the only good roads were in town, the limited range of the EV posed no problem; most driving was local commuting.

The Detroit Electric, one of the most popular EVs then, was said to get 130km (80 miles) between battery charges. Its top speed was 32km/h (20mph), a pace considered adequate for driving. Physicians and women were the main buyers. Thomas Edison, John D. Rockefeller, Jr. and Clara Ford, the wife of Henry Ford, drove Detroit Electrics. Figure 1 shows Thomas Edison with his 1914 Detroit Electric model.

Figure 1: Thomas Edison with a 1914 Detroit Electric, model 47. Thomas Edison felt that nickel-iron was superior to lead acid for the EV and promoted his more expensive batteries.

Source: National Museum of American History

The battery of choice for the EV was lead acid. At a higher price point, the buyer could fit the Detroit Electric with a nickel-iron (NiFe), a battery Thomas Edison promoted for its superior cycle life and good performance at subfreezing and hot temperatures. The NiFe had a cell voltage of 1.2V, was robust and could endure overcharging and repeated full discharging but on a purely performance level, NiFe provided only a slightly better specific energy to lead acid and was expensive to manufacture. In addition, the battery had a high self-discharge of 20–40 percent per month, greater than the 5 percent with lead acid.

In 1914 a devastating fire destroyed the Edison factory, and the popularity of nickel-iron waned. Production of the EV peaked in 1912 and continued until the 1920s. Batteries already posed limitations in the electric powertrain a hundred years ago. Thomas Edison knew this and commented, “Just as soon as a man gets working on the secondary battery, it brings out his latent capacity for lying.”

Henry Ford’s mass-production and cost-cutting measures in 1912 of the Model T were not the only reason for the shift to gasoline-powered cars. The invention of the starter motor in 1912, the need to travel long distances and the discovery of Texas crude oil made the ICE more attractive and affordable to the general public.

The EV became a thing of the past until the early 1990s when the California Air Resources Board (CARB) mandated more fuel-efficient and lower-emission vehicles. It was the CARB zero-emission policy that prompted General Motors to produce the EV1. Available for lease between 1996 and 1999, the EV1 initially ran on an 18kWh lead acid battery that was later replaced with a 26kWh NiMH.

Although the NiMH had an impressive driving range of 260km (160 miles), the EV1 was not without problems. Manufacturing costs rose to three times that of a regular gasoline-powered car. In 2001, politicians changed the CARB requirements, which prompted General Motors to withdraw the EV1, to the dismay of many owners. In the 2006 documentary film Who Killed the Electric Car?, governments give a mixed message regarding cleaner transportation.

Low cost and high current capabilities make lead acid a good candidate for starter applications. It has about 720Wh, is forgiving if abused and cranks the engine even if the capacity has dropped to 30 percent. Batteries for the hybrid electric vehicle (HEV) are about twice this size, and the plug-in has about 12.5kWh; EVs go from 15kWh to 90Wh. Figure 10-3 compares the battery sizes.

EV Chart
Figure 2: Typical battery wattages in vehicles. While starter and hybrid batteries are tolerant to capacity fade, a weak EV battery travels shorter distances.
Courtesy of Cadex

Batteries and cost per kWh vary greatly according to chemistry. Table 3 estimates the price of the most common batteries in use today. At $120 per kWh, a deep-cycle-battery for golf cars and wheelchairs is most economical, followed by the starter, forklift and stationary batteries. Complex manufacturing, electronic safety circuits and battery management systems (BMS) make newer technologies more expensive than older systems, even with volume production.
 

Application Chemistry Capacity Cost/kWh (est.) Battery price
E-bicycle Li-ion 360Wh $1,200 $400-500
Starter Lead acid 0.5-1kWh $160 $120
Golf car Lead acid 8kWh $120 $720 (set)
Forklift Lead acid 18kWh $166 $3,000
Stationary Lead acid Small to large $200 $50,000 typical
HEV NiMH, Li-ion 1-2kWh $500 $2,000–3,000
PHEV NiMH, Li-ion 5–15kWh $500 $10,000–12,000
EV Li-ion 20–90kWh $350 $10,000–30,000

Table 3: Battery sizes of wheeled mobility. Estimated cost/kWh is lowest with lead acid and most expensive with lithium-ion.
 

Last updated 2016-05-30
 

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Comments

On August 8, 2011 at 5:39am
matte wrote:

Interresting read, but, please correct the many places where you have written “W” instead of “Wh” - it makes it really confusing smile
example: “... consumes 15kW of energy”
kW = power
kWh = energy

On August 8, 2011 at 9:20am
Cadex Electronics Inc. wrote:

Thanks I have corrected that.

On September 21, 2011 at 9:12pm
Dhanushk wrote:

Nice article. Thanks

On September 22, 2011 at 6:51am
Robin wrote:

Very interesting, but there are still several places in paragraph 2 where W has been used instead of Wh.  In one place the units are correct in kilometres and wrong in the conversion to miles “Uphill propulsion consumes up to 10Wh/km (16W/mile)”.

Regards,

Robin

On September 22, 2011 at 9:37am
Cadex Electronics Inc. wrote:

Thanks Robin, I have corrected that.

On September 22, 2011 at 2:50pm
Ken Meade wrote:

Is there any area that the Li Fe cell as manufactured by A123 is showing it’s abilities?

Will A123 be able to improve on it’s volume and weight? 

As a hobbyist I really appreciate you’re well done, very informative articles. Thank you!
Ken

On March 7, 2014 at 12:20am
Edward Thirlwall wrote:

It is truly unfortunate that all the green methods are so much more expensive! But we really do need to consider what the best for the environment. All we can really hope for is that in time, and with greater take-up by the public and more extensive use and encouragement, the development of these green energy storage units should be able to improve - cost and efficiency-wise.

On August 22, 2014 at 6:39am
ASHLEY wrote:

Hello,
Cadex, how much (%) a li-ion can reduce in weight when compared to a similar voltage/maH   li-mh   battery?

On August 22, 2014 at 6:43am
ASHLEY wrote:

ups sorry, ni-mh battery

On June 21, 2015 at 4:51pm
Dominick wrote:

I would like to convert a car into electric… i wanna make it as efficient as possible.. being able to run up to 250 miles in one charge… or siimilar.. are there any batteries out there that can help my projects?

Thanks

Dom