Wednesday, February 23, 2011

Volt Battery: Temperature, Temperature, Temperature

     Location, Location, Location.  The three most important rules in real estate.  However, when it comes to the "fifth passenger" in the Chevrolet Volt, the 435 pound battery, the brilliant engineers at GM may have their own mantra.  Temperature, Temperature, Temperature.

     Not only does the Volt's battery have to flawlessly operate daily for a minimum of 8 years or 100,000 miles.  It has to move you and your loved ones safely in America's driest, hottest, deserts.  As well as our most brutal wet, icy, and snow covered winters. The Volt's battery is arranged into nine modules, all situated into a large T-shaped battery pack.  Within these modules are 288 individual cells held in pairs by plastic frames.  In each frame the two cells sandwich an aluminum cooling fin manufactured by Ohio's Dana Corp. Manufacturing company.

     "The Dana Corp.-manufactured cooling fin consists of two lightweight aluminum plates joined by a proprietary clean nickel-brazing process. The grooves stamped into the plates form channels that allow battery coolant that is pumped through the pack to flow over the entire cell surface. The design and construction of that aluminum plate is critical to ensuring an even temperature distribution with no hot or cool spots across the flat, rectangular cell. Batteries that are too cold are reluctant to release electrons, while batteries that run too hot can see a significantly shorter life."

     GM's director of global battery systems Bill Wallace had this to say.  "Every battery has a temperature sweet spot where it provides the optimal blend of power output, energy capacity and long life and we keep the Volt right on that target."  "When the Volt is plugged in and charging in cold weather, an electric heater at the front of the battery pack is used to warm the coolant and pre-heat the battery. During normal operations, the coolant is passed through a heat exchanger at the front of the car, while a chiller in the air conditioning circuit can be used to dissipate heat from the battery when temperatures really climb."

     Wallace went on to say, "Three different systems are used to regulate the temperature of the coolant, when the Volt is plugged in and charging in cold weather, an electric heater at the front of the battery pack is used to warm the coolant and pre-heat the battery. During normal operations, the coolant is passed through a heat exchanger at the front of the car, while a chiller in the air conditioning circuit can be used to dissipate heat from the battery when temperatures really climb."

     16 thermal sensors placed throughout the battery help maintain no more than a 2 degree range from the packs optimal temperature.  15 years of testing batteries and fuel cell stacks has taught GM engineers almost all they've needed to know when it comes to circulating coolant to maintain temperature.

Temperature, Temperature, Temperature.


  1. Looking at my statistics I can see I've had a few hits from New Zealand. My thoughts and prayers go out to you and your family.

  2. "a chiller in the air conditioning circuit can be used to dissipate heat from the battery when temperatures really climb."

    As a resident of the Deep South I'm glad to see this; haven't heard it before.

    I only hope that leaks in the coolant system don't develop over time ... real time that's hard to simulate in the lab.

  3. aw man, you need to do something with this commenting stuff...

  4. ok, now it worked, my first comment got lost somewhere in the ether...

  5. I was just saying that this side seems more interesting than the official blog... and I bookmarked it.

  6. I agree with Vanuck. This side is more interesting.

  7. Me too Jackson, I'm in Florida, a definite must down here. We should probably still try to park our Volts in the shade though.. I'd bet batteries in Arizona will probably go the quickest.

  8. You're definitely the better writer.

    Also, the official blog is getting harder and harder to live with; given all the basic html issues which a) don't get fixed b) made worse in attempts to get them fixed.

    Hang in there ...

  9. Thanks guys, at least there's no green text issue here! I wonder how many other sites the person in charge of GM-Volt is committed too.