A recent tear down of the Chevrolet Volt reveals the surprising complexity of this extended range electric vehicle. UBM Tech Insights took apart the car’s battery and charging system to identify the components of each, and it’s making at least some of its results, including photos, available for free here.

It’s been clear for a long time that the Volt is a complicated car. GM prefers to call it “advanced.” To a skeptic, all that complexity means there are more ways for something to go wrong. 

The Volt is an electric vehicle in the sense that it’s powered by an electric motor almost all the time. But it also has a gas-powered engine for extending the car’s range.

In fact, the Volt has two electric motors. One serves primarily as a generator—it’s attached to the gas engine and generates electricity that either recharges the battery or powers the car’s main electric motor.

A complex transmission system also allows the gas engine to connect directly to the wheels. The new teardown looks at the electronics used to control this system. The charging and power distribution system is complex, having over 10 million lines of code and 100 microcontrollers.

Another complication is the fact that the main motor also generates electricity when recovering energy from braking. An inverter system (which includes inverters, rectifiers, converters, and microcontrollers) has two-way AC power connections to the main motor and the generator, which it allow it to deliver power to the motors or to accept power from the motors when they’re acting as generators.

The inverter system's DC connections send power to the battery, and receive power from it. The inverter system also directs DC power to an oil pump in the transmission. Several communications hookups monitor things such as the Volt’s two electric motors, the speed of the gas engine, and signals from the ignition.

The home charger system—which connects to a cord you can plug into an ordinary outlet—is tucked in under the fender, below one of the headlights. It has its own liquid cooling system, with coolant and a pump to circulate it.

In the trunk, a fan-cooled module converts the high voltage (nearly 360 volt) power from the battery to 12 to 14 volt DC power to run the systems powered by a belt-driven alternator in a conventional car.

The car’s lithium ion battery pack is also complex. It consists of 288 cells, 288 voltage sensors, dozens of temperature sensors, a cooling and heating system, and 12 electronic control modules within the battery pack—including about 30 individual microchips, and one control module for the whole pack. These systems are designed in part to balance out differences between the cells that can increase as the cells age—which could increase the life of the battery pack by about 10 percent, according to UBM.

UBM has also done an analysis of what it calls the car’s “infotainment system,” which includes displays to help drivers drive more efficiently.

So what does this all mean for vehicle reliability? It’s probably too early to provide good comparisons to other vehicles, since the car has been on the road in limited numbers and for less than two years. For those interested in what Volt owners have experienced so far (and there have been problems, as with any vehicle) a good source is this owners forum (not GM’s official site).

Dismal sales of the Chevrolet Volt called into question whether the GM could sell the 30,000 Volts it’s said it wants to this year. But part of the problem was the original car, although it operates without gasoline for short trips, didn't meet California’s emissions standards to qualify for carpool access (without a passenger) and a state tax rebate of $1,500. 

Today GM announced that Volt’s with a new low emissions package meet the state's standards, and will be available  at 140 dealerships in California by the end of the month. That’s too late to help February sales figures, but it could give sales a boost in March.

Carpool access is a big deal on the crowded highways of Southern California. GM says commuters who use them cut their driving time by 36 minutes per day.

A Volt outside GM's headquarters in Detroit. Credit: Flickr / Landlessness.

Electric vehicle enthusiasts (and critics) are keeping a close eye on sales of GM’s Volt this year to get a sense of whether electric vehicles will really finally catch on. GM has said that it hopes to sell 30,000 Volts in 2012, which would mean selling, on average 2,500 a month. It’s far short of that pace for January having sold just 603.

The January figure markedly down from December, when GM delivered 1,520. But sales were actually up substantially from the same time last year, when GM sold 321 of the cars—however, at that time, the Volt was only available in a few states. 

GM didn’t meet its goal of selling 10,000 Volts during 2011, for a number of reasons. In fact, it’s still short of 10,000, with total deliveries of 8,600 vehicles since sales began at the end of 2010.

So, do slow sales in January mean GM won't reach its goal?

There are a number of factors that could explain the slow January sales. Customers hoping to get the Federal tax credit for the car for the 2011 tax year may have rushed to buy in December. Also, at the beginning of January, GM announced a retrofit that will make the car safer. The cars on the lots in January (about 4,400 were there at the beginning of the month) were not retrofitted yet, and the parts needed to do the retrofits weren't widely available. So anyone buying a car in January would have to take it back in a month or two to have the changes made. GM also announced in January that cars built later this year would have low enough emissions to qualify for driving in California’s HOV lanes, an attractive perk.

All in all, potential customers had a lot of reasons to wait until later this year to buy a Volt. It’s too early to call whether the company could sell 30,000 this year. It’s also too early to say how important sales of the Volt are, at least in terms of the overall prospects for electric vehicles. But I’d be interested to hear what readers think. How much is riding on the success of the Volt this year?