When the 2015 VW e-Golf was introduced at the LA Auto Show last year, VW said it would come with a water-cooled battery. During the Detroit Auto Show, when the car was trotted out again, VW released a new press release that stripped out the "water-cooled" language, but this change went unnoticed. During a recent VW event in Germany, a friend from Green Car Reports realized that the battery on display did not seem to have any water-cooling mechanisms. That set us off on a bit of a sleuthing and we have now learned that VW is not going to include any active cooling in the upcoming e-Golf. In fact, the company is entirely confident that this car - because of what it's designed to do - doesn't need it.

"The need for a cooling system wasn't there" - VW's Darryll Harrison

VW has been working on an electrified Golf for ages now, and so changes to the plan are to be expected. But battery cooling is vitally important not just to keep the car operating properly but because when things get too hot, there can be serious public relations problems. Nissan began testing a new battery chemistry for the Leaf in 2013 after an uproar from warm-weather EV drivers in Arizona who were experiencing worse-than-expected battery performance. The Leaf has always used an air-cooled battery, which is another way to say that there is no active cooling system (more details here). Tesla CEO Elon Musk once said this approach is "primitive." So, why is VW following the same path?

We asked Darryll Harrison, VW US's manager of brand public relations west, for more information, and he told AutoblogGreen that VW engineers discovered through a lot of testing of the Golf Mk6 EV prototypes, that battery performance was not impacted by temperatures when using the right battery chemistry. That chemistry, it turns out, is lithium nickel manganese cobalt oxide (NMC) in cells from Panasonic. These cells had "the lowest self-warming tendency and the lowest memory effect of all cells tested," Harrison said. He added that VW engineers tested the NMC cells in places like Death Valley and Arizona and found they didn't warm very quickly either through operation, charging (including during fast charging) or through high ambient temps. "The need for a cooling system wasn't there," Harrison said. Since the cells work so well, all the e-Golf needs to keep the battery pack at the right operating temperature is an intelligent thermal control (which regulates the amount of energy expended form each of the cells to keep the heat down) and the ability to dissipate what heat is created into the chassis and away from the pack.

The VW GTE plug-in hybrid does have a liquid-cooling system.

While we will have to see if the lack of an active-cooling system works in the real world when the e-Golf goes on sale, it's clear that it brings with it the additional benefit of lower weight. The ultimate function of everything in the e-Golf is to be efficient, even if that comes at the expense of high performance, Harrison said, so limiting the battery pack's performance to keep heat in check is appropriate. VW is playing a different game in the GTE, which does have a liquid-cooling system. That car is designed to be a hybrid-electric version of the sporty GTI. Since the dynamics are tuned for performance, the GTE's pack will be cared for in a different way than the gentleness at play in the e-Golf. It's an interesting strategy and one we'll be following closely from here on out.

For the record, we've included the detailed statement that Harrison emailed AutoblogGreen below.
Show full PR text
Generally speaking, regarding the system, it's important to note that the e-Golf was designed with efficiency in mind. The battery pack utilizes ultra-efficient lithium-ion cells that deliver 25Ah per cell with an energy density of 59Wh per lb. The pack is comprised of 264 cells, packaged into 27 modules (of either 6 or 12 cells) delivering 323 volts and weighing in at 700 lbs. As it relates to battery temperature, VW has developed a Battery Management Unit with an intelligent thermal control that allows the pack to remain within an optimal temperature window, helping to maintain performance and range in a variety of temperatures. This system allows the e-Golf to operate, even in more extreme temperatures, without the need of a cooling system and without dramatic impacts in performance based on testing.

In terms of the battery pack, the engineering goal was to develop a highly efficient system as opposed to one that focused on charge-time or capacity (like some of our competitors). In partnership with Panasonic, VW utilizes a lithium-ion cells designed for gentle charge and de-charge during use which helps to reduce heat and energy consumption often associated with cells designed for rapid charging and de-charging. Our engineers refer to them as "marathon cells." Additionally, without a cooling system weight savings are achieved which aides in overall efficiency of the vehicle. Due to the efficiencies achieved, minimal waste heat is created during operation (i.e. during fast charging) and is quickly directed by the battery metal structure into the chassis, away from the battery, helping to prevent extreme temperature conditions inside the pack.

Our engineers tell us that the e-Golf has passed various long-term engineering evaluation milestones in desert temperatures and cold weather climates, without the necessity of a cooling system.


I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.


    • 1 Second Ago
  • 71 Comments
      2 wheeled menace
      • 8 Months Ago
      You have the right battery when no cooling or heating system is required. :) " These cells had "the lowest self-warming tendency and the lowest memory effect of all cells tested," Harrison said." Did Harrison really say that? i hope he understands that no lithium battery has any kind of memory effect at all.
      Joeviocoe
      • 8 Months Ago
      I think people are confused about what it means to have good "performance" in the desert. It seems like VW here, and Nissan a few years back... tend to consider their "performance" testing in deserts good enough to make claims that their EVs don't need active cooling. There is a big difference between sufficient "performance" in the desert... and long term "durability" or "longevity" in hot climates. The battery may have good power output while at 130 F... but what will the capacity degradation be if the EV is left in that climate for 2 years or more? Spending a month or two in the desert won't really tell us much... and that kind of extrapolation really bit Nissan in the ass. Like Rak said, they likely don't have any plans to sell in Arizona. (or don't have any plans outside of short term leasing).
        2 wheeled menace
        • 8 Months Ago
        @Joeviocoe
        Nissan's ~5C cells couldn't have taken it. But i know many chemistries that can. VW is not necessarily lying or overselling things.
        AndY1
        • 8 Months Ago
        @Joeviocoe
        No need for Arizona for that kind of temperatures. In the Central Europe, we had 40°C-43°C for 3 weeks last year. My Ampera actively cooled the battery during charging, driving and being parked in the sun (with the screen over the front screen), keeping it between 24°-30°C. In the 20 months of ownership, I've driven 45.000km and I notice no visible degradation of the battery when looking at all electric range I do.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          That is just the point Andy.... for 3 weeks... that is nothing like Arizona which has a LOT more days of the year at high temps. The idea that one could just extrapolate from very short duration testing... had failed Nissan before.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
          Joeviocoe
          • 2 Hours Ago
          @AndY1
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
        DarylMc
        • 8 Months Ago
        @Joeviocoe
        There is a video here about some of VW's battery testing. https://www.youtube.com/watch?feature=player_detailpage&v=7DHUR1oqZ5c#t=270 They claim to have done a lot of long term charging and discharge testing in climate controlled enclosures.
          Joeviocoe
          • 2 Hours Ago
          @DarylMc
          Good video Daryl... will watch Andy's a bit later. My concern is still that the "performance of charge/discharge", as shown in the video... is independent of the long term heat soaking found in the real world in Phoenix. Automakers, like Nissan, have also done similar tests as VW. They mainly focused on simulating many charge/discharge cycles while at extreme temps. But can only extrapolate how calendar life is affecting the capacity over years. Cycle life and Calendar life are mostly independent of each other. And extreme temperatures while driving or charging, may be acceptable... but that is a factor of cycle life. Extreme temperatures while sitting on a blacktop for 100+ F days... affects the calendar life... which is why it only shows up in real world testing and was a complete surprise to Nissan too.
          Joeviocoe
          • 2 Hours Ago
          @DarylMc
          Andy... awesome video. Definitely a lecture for graduate students, although the professor did make it simple enough. It seemed like he hit the nail on the head as to why Nissan failed to predict the effects of prolonged heat soaking while not even charging or discharging... like the Leafs sitting at 80% charge on hot blacktop that kept them at high temps. It appears from Daryl's video, that VW did not test for precision coulombic efficiency... but instead, the same way the Nissan tests... by extrapolating cycle life degradation with rapid charge and discharge cycles.... and NOT showing the calendar life degradation by cycling much slower.
          AndY1
          • 2 Hours Ago
          @DarylMc
          Why do Li-ion Batteries die? And how to improve the situation? https://www.youtube.com/watch?v=pxP0Cu00sZs Worth watching.
          DarylMc
          • 2 Hours Ago
          @DarylMc
          Thanks Andy That was tough going to watch though but I get the idea. To me it shows the costs involved and challenges of developing battery packs for EV's. Tesla really seems to have made some good decisions in this regard. Though I do wonder how well they will be able to scale it down for a smaller vehicle.
      Rotation
      • 8 Months Ago
      This is the same stuff that Nissan told us. And the idea the the cells don't heat up from high ambient temperatures is ridiculous. It's basic thermodynamics.
      dan.frederiksen
      • 8 Months Ago
      It's wildly irrelevant since the car will obviously suffer the usual old garde nitwit evil punishment price. but as an academic discussion, you'd probably need at least air cooling for hot regions if the battery in question has calendar thermal issues. Like Nissan's does. I'm not a believer in liquid cooling. It's a needless complication and a risk.
      dan.frederiksen
      • 8 Months Ago
      Why does autoblog keep effing up their commenting system..
      Val
      • 8 Months Ago
      Isn't this the exact same cell chemistry that Tesla is using? What was the revolutionary change that suddenly made those cells immune to the effects of temperature, especially fast charging? What about cold weather, when the battery can't deliver even half of its stored energy? And the power has to be limited so as not to damage the battery, until it is brought up to temperature? Did tesla implement that heating system for no reaso at all, just to make the car heavier, more complex and more expensive?
        2 wheeled menace
        • 2 Hours Ago
        @Val
        There are many different formulations of NMC out there. Some of them potent and resilient, some wimpy and fragile... it all depends on the design.
        Dave R
        • 2 Hours Ago
        @Val
        Tesla uses a Lithium Cobalt (LCO) chemistry. Has good calendar life, very high energy density, but not as thermally stable as NMC.
          Val
          • 2 Hours Ago
          @Dave R
          Pure cobalt chemistries are REALLY expensive, one of the main reasons cobalt is being replaced, is the price, and the fact it only comes from one mine in africa basically. It is also quite unstable apparently. According to this article, the golf uses nickel manganese cobalt oxide (NMC). According to greencarcongress, Tesla uses NCA: Currently, the Model S pack comprises up to around 7,000 Panasonic NCR18650A 3100 mAh 18650-size cells using a Lithium nickel cobalt aluminum (NCA) chemistry and proprietary cathode geometry developed by Panasonic and Tesla. The cathode formulation has been specifically optimized for EV applications. So both have cobalt, mixed with neckel, and either aluminum or manganese. You can bet that the ammount of cobalt in both cells is very similar. And they are both more stable than traditional LCO cells found in laptops.
      Levine Levine
      • 8 Months Ago
      VW is cutting corners again.
      Levine Levine
      • 8 Months Ago
      VW is cutting corners again.
        Electron
        • 2 Hours Ago
        @Levine Levine
        VW is definitely not beyond cost reductions at the consumer's expense.
      raktmn
      • 8 Months Ago
      Either they have the magic battery chemistry, or they have zero plans to sell them in Arizona.
        Michael Walsh
        • 8 Months Ago
        @raktmn
        I wouldn't even take one in Southern California!
        2 wheeled menace
        • 8 Months Ago
        @raktmn
        Plenty of chemistries and pack configurations can handle the lack of cooling/thermal management. I've been running one of them on my ebike for 4 years.
          Joeviocoe
          • 2 Hours Ago
          @2 wheeled menace
          I was asking 2WM. He's the one with a 4 year old battery with no thermal management. You're right, the passive convection cooling works much better for a bike, than a car with a underside pack facing radiative heat from hot black top.
          Joeviocoe
          • 2 Hours Ago
          @2 wheeled menace
          I was asking 2WM. He's the one with a 4 year old battery with no thermal management. You're right, the passive convection cooling works much better for a bike, than a car with a underside pack facing radiative heat from hot black top.
          Joeviocoe
          • 2 Hours Ago
          @2 wheeled menace
          I was asking 2WM. He's the one with a 4 year old battery with no thermal management. You're right, the passive convection cooling works much better for a bike, than a car with a underside pack facing radiative heat from hot black top.
          Jesse Gurr
          • 8 Months Ago
          @2 wheeled menace
          Yes, actually, I do.
          Joeviocoe
          • 2 Hours Ago
          @2 wheeled menace
          I was asking 2WM. He's the one with a 4 year old battery with no thermal management. You're right, the passive convection cooling works much better for a bike, than a car with a underside pack facing radiative heat from hot black top.
          Joeviocoe
          • 2 Hours Ago
          @2 wheeled menace
          I was asking 2WM. He's the one with a 4 year old battery with no thermal management. You're right, the passive convection cooling works much better for a bike, than a car with a underside pack facing radiative heat from hot black top.
          Joeviocoe
          • 8 Months Ago
          @2 wheeled menace
          I was asking 2WM. He's the one with a 4 year old battery with no thermal management. You're right, the passive convection cooling works much better for a bike, than a car with a underside pack facing radiative heat from hot black top.
          Jesse Gurr
          • 8 Months Ago
          @2 wheeled menace
          At least you have good airflow around the battery on the ebike. In a car, its in a spot with hardly any ambient airflow.
      Jim McL
      • 8 Months Ago
      Jeff, NMC does fine down to about -15 F for charging, even lower for discharge. And the high end is not a problem. LiFePo is nice and comfy safe but has lousy energy density and many versions cannot charge below +30 F, which is a big problem. NMC has much better energy density than LiFePo but not as high as that nervous Lithium cobalt in laptops. Engineering compromises... Tesla seems to be going for lowest cost per watt hour and will take on some risk with that Lithium Cobalt Aluminum but I don't know much about it. Perhaps it is good enough to just be safer than gas cars.
      jeff
      • 8 Months Ago
      The ONLY chemistry (available in mass production) that does not need active cooling is LiFePo4... They love the heat and do not have much temp rise on heavy amp draw... They still would benefit from active heating in cold weather though... I guess this is the Weekly VW press release and still not actual cars..... It really is getting to be a stale joke now...
        DarylMc
        • 2 Hours Ago
        @jeff
        Hi jeff Better late than never. Of course they will have plenty of chance to disappoint purchasers even once they arrive. Hopefully Volkswagen has done its homework and their electric cars will be quite solid. If they do not perform well, Volkswagen will have certainly wasted the money they have put into developing them. No one is questioning Tesla's commitment put more EV's on the road and Tesla Model S is still not available here in Australia. I think the electric Golf is likely to address many peoples concerns about the similarly specified Nissan Leaf, particularly when it comes to the styling of the vehicle. Regarding battery degradation, who can say until it has been put to use. As far as I can tell you will see the Golf EV released in the USA late this year. No one in the world is spoiled for choices when it comes to EV's right now.
        Dave R
        • 2 Hours Ago
        @jeff
        LiFe is NOT the best lithium battery in the heat. It is better than Nissan's LMO, but that's not saying much.
        2 wheeled menace
        • 2 Hours Ago
        @jeff
        Nope.
        2 wheeled menace
        • 2 Hours Ago
        @jeff
        Nope. Absolutely wrong.
      Jesse Gurr
      • 8 Months Ago
      "VW utilizes a lithium-ion cells designed for gentle charge and de-charge during use which helps to reduce heat and energy consumption often associated with cells designed for rapid charging and de-charging." "Due to the efficiencies achieved, minimal waste heat is created during operation (i.e. during fast charging)..." Couple of things: 1) I'm pretty sure the term is "dis-charging". If you are a PR guy, you should know what terms to use and do a little research before using terms you are obviously unfamiliar with. 2)He said they are using a battery designed for gentle charging and dis-charging, then he goes on to say that minimal heat is creating when fast charging. Using fast charging on cells not meant for it seems a little "off". I will believe it when I see it.
        2 wheeled menace
        • 8 Months Ago
        @Jesse Gurr
        I don't think he knows entirely what he's talking about, but what i get from this is that the cells are overrated, which is a very good thing. ultra low internal resistance, vastly overrated = higher efficiency and better range from a battery; and as it ages and gains internal resistance over many years, it will still perform well throughout it's life rather than showing massive voltage sag and the BMS ends up cutting off the battery early.
        2 wheeled menace
        • 8 Months Ago
        @Jesse Gurr
        I don't think he knows entirely what he's talking about, but what i get from this is that the cells are overrated, which is a very good thing. ultra low internal resistance, vastly overrated = higher efficiency and better range from a battery; and as it ages and gains internal resistance over many years, it will still perform well throughout it's life rather than showing massive voltage sag and the BMS ends up cutting off the battery early.
        2 wheeled menace
        • 8 Months Ago
        @Jesse Gurr
        I don't think he knows entirely what he's talking about, but what i get from this is that the cells are overrated, which is a very good thing. ultra low internal resistance, vastly overrated = higher efficiency and better range from a battery; and as it ages and gains internal resistance over many years, it will still perform well throughout it's life rather than showing massive voltage sag and the BMS ends up cutting off the battery early.
    • Load More Comments