Not so on this 1997 night. I was driving an EV1 development vehicle freshly equipped with an experimental nickel-metal-hydride (NiMH) battery pack. We were developing NiMH - which was promising double the usable energy of our '97 advanced lead-acid (PbA) packs in about the same (nearly 1200-lb.) package - for the '99 model year.
As GM Advanced Technology Vehicles' test and development manager at the time, I routinely drove PbA EV1s home and back, re-charging overnight, during the summer. My 60-mile mid-Michigan commute was easily doable in warm, but not cold, temperatures.
When the mercury sank, so did range, due partly to reduced PbA performance but mostly to lost vehicle efficiency. Our 50-psi Michelin low-rolling-resistance tires became just average at low ambient temperatures. Cool seals, bearings and lubricants have more friction. The air flowing over and around our 0.19-Cd electric bullet got thicker and more viscous as temperatures fell. Then there are accessory loads: lights, heater and (in wet weather) wipers.
But this was a hot, dry summer night, my NiMH pack should have been good for 120 miles, and my after-work meeting was only 30 miles from work. Should have been a piece of cake to get home afterward, even with lights on at 70-80-mph freeway speeds. But it wasn't. (post continues after the jump)
I missed a turn at the first freeway split and wasted maybe eight miles driving to the next exit and back, but something else was not right. As the EV1's very accurate range gauge turned pessimistic, telling me I would not get home before running out of volts, I shut off the A/C and incrementally reduced speed. But I couldn't risk turning off the lights or going too slow on the freeway. I pondered how thrilled my wife would be come out to rescue me, and the risks of leaving the car on the shoulder overnight.
Shortly before my exit, the EV1 went into its limited-speed, "limp-home" low-range mode. I crept along the shoulder a couple more miles to my exit, then - ever more slowly - eight more to my garage. No fun, not safe, but it got me there. Whew!
My one-hour drive had taken more than two, elevated my heart rate and caused serious sweat production. And what if I'd had to make a stop, or pick someone up, on the way?
The problem was traced to a NiMH trait (at least at that early stage of development) of which we had been unaware: it lost energy capacity when hot. Because of this, our engineers added battery cooling ducts around the pack for '99, and the NiMH option was not offered in hot-weather Phoenix and Tucson.
This was the first time I experienced serious range anxiety. We've all had the experience of running low on fuel in conventional vehicles with no station in sight. And we've either found fuel in time or had to get out and walk to bring a can back to the car.
Unfortunately, we can't carry a can of volts. If an EV goes dead, you leave it. If you're really lucky, you might get close enough to a home or business whose owner will let you plug in, but what will you do for the next few hours while it slowly charges on house current? The other option is to retrieve it later with a tow truck or flatbed. And forget the rest of your trip.
In my opinion, range anxiety is the single biggest obstacle in the way of widespread consumer acceptance of battery electric vehicles. Every EV at any price can carry only a finite amount of energy and will consume it at a (highly variable) rate dependent on its size, weight, feature content, load, operating efficiency, weather and, yes, operator skill.
Our original EV1 carried 16 kilowatt-hours (kWH) of energy – roughly half-a-gallon of gasoline – in a large, 1170-lb. T-shaped pack of 27 PbA batteries that ran down the wide center console and behind its two bucket seats. Given that an electric propulsion system is about three times as efficient as a typical internal combustion engine (ICE) powertrain, you could think of that gasoline equivalent as more like 1.5 gal.
How far will your car go on 1.5 gallons? To achieve a reliable real-world range of even 60-70 miles, our EV1 was designed and built from the tire patches up to be the most energy efficient practical vehicle that ever rolled down the road. Some skilled drivers could feather-foot 90, or even 100, miles out of one on flat surface streets on a warm day. Our optional '99-model NiMH pack could virtually double that.
We know that today's li-ion batteries should pack nearly twice the energy of NiMH and quadruple that of PbA. But they are still fairly large, bulky and heavy and will likely be much more expensive. EV makers, as always, will face the decision of how much to carry on board -- how much cost, weight and packaging will be needed to achieve how much on-board energy?
Battery EV owners will have to fully understand how to operate within their vehicles' real-world range, which will vary with conditions, each day, and exactly where and when they can recharge. As the infrastructure grows (with heavy taxpayer, utility and maybe automaker investment), recharging at work should be possible for some, and large shopping and dining areas should offer public charging. But they won't drive them cross-country any time soon.
One well-proven (but expensive) way to eliminate range anxiety is to marry an ICE to the electric motor through a complex control and transmission system. This is the essence of Toyota's and Ford's parallel hybrid systems. Another is to add a smaller, lighter ICE for range-extending battery charging only. This is GM's (also expensive) series-hybrid Voltec (neé E-Flex) system everyone hopes will be available in the 2011 Chevy Volt and, in time, other GM cars.
GM says the Volt's li-ion pack will carry 16 kWH, exactly the same as our original '97 EV1's PbA pack, but will be much smaller and about a third the weight. And, because the Volt will be a practical four-seater, necessarily heavier and less efficient than the EV1, that energy will propel it only about 40 miles on a charge. Then that very efficient little ICE will crank up to help complete the trip, no matter how far. What range anxiety?