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Weak Battery Explains Death Of Cadillac SRX Plug-In Hybrid

 
1,799 views Jun 2, 2011
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2010 Cadillac SRX Turbo

2010 Cadillac SRX Turbo

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Well, now we know a little more about why the Cadillac SRX Plug-In Hybrid project was killed by its development team at General Motors.

The culprit, according to GMInsideNews, was the lithium-ion battery pack.

More specifically, it wasn't providing the efficiency gains that would have been needed to make the car viable.

The SRX Plug-In Hybrid was to have been the most advanced version of a new generation of GM's Two-Mode Hybrid system. As well as refinements to its operating modes, it was to use a lithium-ion battery pack rather than the current system's older nickel-metal-hydride pack.

But according to GMI's sources (who tend to be right more often than not), the proposed new pack just didn't cut it. The minimum requirement would have been 10 miles of electric range, which had been promised for the Saturn Vue Two-Mode Plug-in Hybrid version originally scheduled for 2010--the first of several vehicles in the whole sorry saga.

The Two-Mode Hybrid system, originally a joint venture among GM, DaimlerChrysler, and BMW, was developed before the Voltec extended-range electric system used in the 2011 Chevrolet Volt.

Saturn Vue Two-Mode Hybrid

Saturn Vue Two-Mode Hybrid

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Now, it appears that elements of the Voltec system may play into a revised design for the big hybrid technology, which may have four modes rather than two--leading some to refer to it as the "Four-Mode Hybrid" system.

The key question will be the source of the lithium-ion cells in the battery pack. Hybrid systems that don't plug in prioritize power (quick delivery of energy for short periods) over energy (high capacity for storing lots of energy for longer ranges).

The Volt's battery pack is an "energy" pack, whereas the older Two-Mode packs were "power" packs.

Perhaps an adaptation of the Volt pack--for which LG Chem supplies the cells--might be used for the new plug-in hybrid version?

We'll have several years to find out, anyhow. The new generation of the Two-Mode system isn't expected to launch until 2015. The SRX Plug-In Hybrid was to have gone on sale in 2013.

[GMInsideNews]

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Comments (6)

  1. fb_100000005296979 avatar Kent Beuchert Posted: 6/2/2011 10:54am PDT

    You mean that after all those years testing and thinking about battery packs for their Volt, GM engineers were still clueless about what was required for their long announced plug-in hybrids? I'm not buying this rather confused explanation of theirs.
    Probably what they found out was that a small battery pack can't produce enough power for their hefty Caddy.
    This business of power versus storage capacity is bogus. If this were true, then how come the Volt has enough power, yet the equally heavy Caddy does not?
     
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  2. fb_1001015277 avatar John Briggs Posted: 6/2/2011 11:52am PDT

    I was thinking, that when you have a large (energy) enough battery pack, like the Volt, then you pretty much are guaranteed to have enough power. However, with a small battery pack (like the Prius), it has to be specially engineered for power.

    Also, I thought I had heard that Toyota was behind the curve on plug-ins because the had accidentally back the wrong horse. The particular Li battery technology that they had been pursuing didn't hold up under testing and they needed to start again.

    I guess the same could have happened to GM. The details of the Li battery didn't work out for them.
     
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  3. MichaelThwaite avatar Michael Thwaite Posted: 6/3/2011 5:31am PDT

    Large hybrids, do they work at all? VW demonstrated that the Toureg Hybrid only get 4mpg city and 1 mpg highway over the standard car... for a $20,000 price increase. Perhaps there's more kit on the hybrid version and granted that is a 25% improvement (city) but at 20mpg it's still below the US average MPG.
     
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  4. john_v avatar John Voelcker Posted: 6/3/2011 6:27am PDT

    Michael: True, but remember that 4 mpg from 16 to 20 mpg saves way more actual gallons of gasoline (12.5 gal per 1,000 miles) than 4 mpg from, say, 36 to 40 mpg (only 2.8 gallons).

    So while higher mileage is always better, raising mileage on the worst vehicles (large SUVs, say) makes more of a difference than increasing mileage on low-consumption cars.
     
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  5. fb_1001015277 avatar John Briggs Posted: 6/3/2011 7:02am PDT

    Michael, once again, Voelcker brings out this tired and wrong-headed argument. The truth is that VW created a poor hybrid system. So the question isn't do hybrids work on large vehicles. It is a good vs bad hybrid question. Here is the data.

    16/23 MPG VW Tourag non-hybrid

    17/22 MPG Toyota Highlander non-hybrid.

    I will claim these to be similar vehicles for my argument.

    20/24 MPG VW Tourag hybrid

    28/28 MPG Toyota Highlander hybrid.


    Here you can see the difference between good hybrid and bad hybrid. VW gets 25% better MPG city. Toyota gets 65% better MPG city.

    So hybrid technology can work in these vehicles, it is just not everyone is as good at it as Toyota is.
     
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  6. fb_1001015277 avatar John Briggs Posted: 6/3/2011 11:56am PDT

    Need to link this to Mr. Voelcker's new article that says the battery was not, in fact, the problem.
     
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