Credit: GM

Today GM announced that it will introduce changes to the Chevrolet Volt to guard against fires like the ones that occurred after crash tests last year.

New Volts will incorporate the changes, including steel reinforcements, starting this month. The approximately 12,000 cars that have already been built (about 8,000 have been sold so far) can also be retrofitted at dealerships starting in February. The retrofits will be part of a voluntary program, not an official product recall.

GM has also confirmed what caused a handful of Volt battery fires in testing last year. A side-impact test caused part of the Volt's structure to break into the battery casing, and a small coolant leak was exacerbated when, as part of the test procedure, the battery was slowly turned over. When the battery pack was upside down, the coolant leaked onto a circuit board, which caused a short, and then the fully charged battery caught fire.

The fires could likely have been avoided if the batteries had simply been drained of charge after the test—much as a conventional vehicle would have its gas tank drained. The fires didn't start right after the crash tests, so there would be plenty of time to do this. But the changes to the Volt are meant to prevent coolant leaks as the result of a side-impact collision.

Much has been made of the fact that the Volt battery pack isn't encased in metal, while the pack for the Nissan Leaf electric car is. But the Volt pack is, in fact, well protected by a steel tunnel built into the floor of the car.

Battery Reinforcements: Engineers add steel brackets to the undercarriage of the Chevrolet Volt. Credit: GM

GM is adding extra steel braces to the steel tunnel to further protect the battery. The company says tests show this will prevent coolant leaks. GM is also adding coolant level sensors and a special tamper proof cover meant to prevent overfilling of the coolant.

Mary Barra, GM's senior vice president of global product development, said today that the fires were not the result of a problem the battery cells inside the battery pack. She also said no changes will be made to the manufacture of the battery pack itself. And she expressed confidence in the safety of the lithium-ion chemistry GM is using, saying that the cells had been subjected to rigorous tests, including driving nails through them.

Despite all of those tests, apparently the cells—at least when fully charged—are still not robust enough to keep from catching fire after a short caused by a coolant leak.

It's not clear whether a more stable battery chemistry, such as the lithium-iron phosphate materials used by companies such as A123 Systems, could have prevented the fires.

Having a few electric vehicle charging stations here and there isn't a big deal. But if they ever become common in cities, they'll be an eyesore, with their long, tangled black cords clumped onto their sides or sprawling across parking spaces to the outlet on the side of a car. Charging stations could also be a tempting target for vandals.

A much more elegant solution would be to bury inductive chargers under parking spots, a concept that Daimler has started testing. The chargers could be invisible and protected from vandals. And they could make charging easier—just pull into a parking spot, and the car can start charging.

Daimler, along with Conductix-Wampfler, a company based in Germany, has only recently started testing cars equipped with the inductive charging coils. But the initial results look positive.

The system is 90 percent efficient, which isn't as good as charging with a cable, but is better than some other inductive charging systems. The companies say that when you count efficiency losses within the car, the system is almost as good as plugging in.

Daimler has modified a E-Cell plug-in hybrid concept vehicle like this one to allow it to charge without having to plug in. So what will we call plug-in hybrids now? Credit: Daimler

In initial tests, after two or three practice runs, drivers have been able to successfully park their cars so that they're centered over the charging coils.

An object detection system is supposed to avoid the potential problem of the buried coils heating up a piece of metal left on the road. The prototypes are based on a wireless charging system developed for electric buses that has been operating since 2003.

It will be interesting to see how the cost of the system compares to conventional chargers, and whether it will still be necessary to install a post for communications gear, to allow drivers to pay for the charge with their credit cards, for example. Ultimately, cities will have to decide whether the better looks and convenience are worth the sacrifice in energy efficiency.

The company WiTricity is developing chargers that could be more convenient still, charging efficiently at distances greater than is allowed by inductive charging. We featured the technology as one of our 10 Emerging Technologies of 2008.

Today GE announced that it and its venture capital partners are investing $63 million in ten companies developing alternative energy and energy efficiency technologies. Here are some interesting ones.

Witricity's technology, which TR featured as part of our annual TR10 list in 2008, transmits power wirelessly over distances of a couple of meters by manipulating magnetic fields. Maybe it will help make electric vehicles more popular: you could charge by simply parking over one of the company's devices.

GMZ Energy makes thermoelectric materials, which convert heat into electricity—TR wrote about the technology in 2008. The researchers who founded the company improved the performance of a thermoelectric material by 40 percent by crushing it to form fine, nanoscale powders, then packing the powders to form thin wafers.

Project Frog designs and builds kits for making efficient and inexpensive buildings. The kits are adapted for specific locations and can be designed to use zero net energy, which means they generate as much as they consume.

Nuventix has developed a method to keep LEDs from getting hot, which reduces their efficiency. Typically LEDs are cooled with heat sinks, but those are bulky. The company has developed a small and quiet air-cooling system —based on the company's demo, it looks a lot like a speaker. A diaphragm quickly forces air through a channel, creating a jet that cools the LED.

VPhase cuts home energy use by reducing the voltage that enters a house, while still maintaining the level needed for appliances and electronics to function properly. It's based on voltage regulation used in commercial and industrial settings, but made cheaper for home use.

Here's a complete list of the companies:

Ember, Boston, Massachusetts (Communications and software)

GMZ Energy, Waltham, Massachusetts (solar systems and services; co-investment with KPCB)

Hara, San Mateo, California (Communications and software; co-investment with KPCB)

Nuventix, Austin, Texas (Building efficiency)

On-Ramp Wireless, San Diego, California (Communications and software)

Project Frog, San Francisco, California (Building efficiency; co-investment with RockPort Capital)

SunRun, San Francisco, California (Residential solar systems and services; co-investment with Foundation Capital)

Viridity Energy, Conshohocken, Pennsylvania (Communications and software)

VPhase, Manchester, United Kingdom (Building efficiency)

WiTricity, Watertown, Massachusetts (Communications and software)