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Eight 2011 Chevy Volts took the 1200-mile roadtrip.  (Source: Jeffrey Sauger for General Motors)
The Volt is withstanding the rigors of road testing admirably

The first preproduction models of the 2011 Chevy Volt hybrid electric plug-in vehicle were built earlier this year.  Since then, the vehicle has been put through a number of rigorous tests.  Starting yesterday, a fleet of eight Volts launched on the most ambitious test of the vehicle to date: a 1,200 mile road trip.

Chevrolet Volt chief engineer Andrew Farah is among those making the round trip from the Milford Proving Ground through Ohio, Pennsylvania, Maryland, West Virginia, before returning home.  The drive will take a few days and will require approximately 4 tanks of gas.

The drive is dubbed the "65-Percent Drive" according to Autoblog, which in GM-speak means the test drive made when 65 percent of the vehicle's hardware and software is done.  Reportedly, GM is actually about 90 percent done, but is just sticking to its traditional naming.  GM will complete 70, 80, 90 and 100 percent drives in coming months.

One thing GM is still tweaking is how much power from the gas-engine generator to put directly to the electric drive motor, versus using the generator power to charge the batteries.  GM is finding that frequently putting the power directly to the motor improves performance.  However, the generator will still charge the batteries in some cases, as well.

The engine will be run between 1,200 and 4,000 rpm, using factors like speed and power load requirements to decide on the necessary speed.  GM wants to keep the engine between 30 to 100 percent load, as higher loads reduce pumping losses.  GM was tight lipped about fuel economy under the old method (sustained charge) or the new method (variable speed, some power going directly to the electric motor). 

The company did say that the prototypes are getting good mileage -- over 300 miles on a tank of gas -- when operating in generator mode.  This is in addition to the vehicle's 40 mile all-electric range.  Another interesting test will be when GM runs the car's gas engine on E85 ethanol fuel.  The vehicles are FlexFuel designs, so they can enjoy both gas and ethanol.

As to the battery mode, the batteries are performing well and aren't getting too cold or too hot, both conditions which can degrade performance.  The cars aren't yet reaching the 40 mile target on a charge, but GM expects to pass that milestone on the next test, with tweaking.  On the trip, GM is testing vehicles both running on a depleted battery charge, and a full charge.

GM is also looking to fine tune and minimize noise, vibration, and harshness (NVH).  Currently, the gas engine typically won't turn on until the car is moving, at which point the noise will be drowned out by the wind and road noises.  GM, nonetheless, is pleased with the performance, and plans to further reduce NVH by tweaking vehicle parameters that effect the road and wind noise.

Other GM engineers were off testing Volts at Pikes Peak in Colorado.  One key concern is whether the Volt will reach a "tipping point", where the gas engine can't sustain battery charging, and the battery becomes depleted below the typical minimum of 30 percent charge.  Even a strenuous 14-mile trip to the 14,000-foot summit was unable to overwhelm the 100 hp generator, though, so it appears that the "tipping point" will never be reached in real world situations  -- if GM's claims hold true.

A critical test to come will be how the vehicle performs in cold weather.  In cold weather, the Volt starts with the generator running, to help heat up vehicle and jump-start performance.  Battery performance typically suffers incrementally worse degradation, the colder it gets (this is a major argument for ultracapacitors which perform favorably, but are more expensive).

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RE: a tank is a tank...
By invidious on 10/16/2009 2:42:41 PM , Rating: 1
The volt is not an EV, its a hybrid. It has breakbads so yes they will need to be replaced. It has an engine so it will need oil.

Also your assumption that a perfect EV would not have breakpads is incorrect. Electromagnetic breaks do not work fast enough to compare to break pads.

RE: a tank is a tank...
By mcnabney on 10/16/2009 2:48:20 PM , Rating: 3
This car will only put wear on the brakepads when stopping suddenly or sharply. I would imagine that this would at least triple their life expectancy.

RE: a tank is a tank...
By Keeir on 10/16/2009 7:13:11 PM , Rating: 2
Errr... maybe you missed the "Little" part? Most electric motors are capable of providing 70%+ of braking needs. GM is actually adding two Regen Modes. One mode will feature heavy regen once you release the gas pedal. In this mode, its entirely possible that brakepads/brakes that used to last ~50,000 miles will corrode before they wear out from actual use. It depends on what type/quality GM decides to put on the Volt. At 40,000 a pop, I hope its some that "never wear out". I guess also if your the type that speeds to stop signs and redlights you might have an issue too.

RE: a tank is a tank...
By Alexvrb on 10/17/2009 3:44:53 PM , Rating: 2
A modern set of good quality, properly coated, well lubricated brake pads will last a long time in typical circumstances before they corrode beyond safe use. Especially given that modern calipers are well coated (and sometimes made of aluminum), and they use phenolic pistons. So I don't think this will be much of a concern.

The rotors on the other hand... if they use steel rotors, those will rust out eventually no matter what. You'll be using the pads just often enough (under heavy braking) to keep the rotor and pad contact surfaces pretty clean. They could even coat everything but the contact surface of the rotor, but that would generally be overkill. Rotors are cheap enough (even OE or Wagner/Raybestos/Bendix) that replacing them in 5+ years due to rust is still a lot cheaper than using something outrageously expensive like carbon-ceramic rotors (typically used for their high-performance properties only).

RE: a tank is a tank...
By Jeffk464 on 10/18/2009 10:49:43 AM , Rating: 2
they are good enough to stop a mag lev train.

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