Volkswagen’s strategy for batteries

2015 Volkswagen e-Golf battery

Volkswagen’s strategy for batteries could be resumed to using the same cells for BEVs and PHEVs. It has its pros and cons. But we’ll look into it ahead.

 

Volkswagen currently uses 25 Ah NMC cells made by Sanyo (owned by Panasonic) to make the batteries for its BEVs and PHEVs.

While it’s not easy to find simple information like weight and volume of these cells, Joachim from endless-sphere.com forum got some units and we now have some data.

 

Volkswagen cell module made with Sanyo NMC cells (6s2p)

 

Weight: 724 g

Dimensions: 14,7 x 9 x 2,5 cm

Volume: 0,33075 L

Nominal capacity: 25 Ah

Nominal voltage: 3,667 V

Volumetric energy density: 277 Wh/L

Gravimetric energy density: 126 Wh/kg

 

Sanyo 25 Ah cell used by Volkswagen

 

But these 25 Ah cells are about to be replaced.

In January 2017 Volkswagen will start replacing the 25 Ah Panasonic/Sanyo cells with 37 Ah Samsung SDI cells.

Nevertheless even the new cells have average energy density, not great, because they are a compromise.

Usually automakers use different cells for BEVs and PHEVs, cells with more energy density are used in BEVs and cells with more power density are used in PHEVs. Volkswagen is the exception, the automaker uses the same cells for BEVs and PHEVs. This means that the cell’s characteristics are a compromise between energy and power density. The cells will never have an energy density nor a power density as good as they could, this is the biggest disadvantage of this strategy.

 

But there are a lot of advantages.

 

  • Using the same kind of cell in every plugin car allows Volkswagen to use volume to negotiate prices with the cell maker.
  • The cell maker can focus on just one kind of cell, maximizing resources for R&D (Research and Development) and minimizing production costs by requiring less machinery.
  • It makes battery upgrades easier. When a new higher capacity cell is introduced it can easily be used in every Volkswagen plugin car. This is what will happen with the introduction of the 37 Ah cell to every BEV and PHEV made by the Volkswagen Group.

 

In 2017 Volkswagen will surely have one of the lowest costs per kWh, certainly below 140 €.

These are the plugin cars of the Volkswagen Group that will use the 37 Ah cells:

 

  • Volkswagen e-Golf
  • Volkswagen e-up
  • Volkswagen Golf GTE
  • Volkswagen Passat GTE
  • Audi A3 e-tron
  • Audi Q7 e-Tron
  • Porsche Cayenne S E-Hybrid
  • Porsche Panamera 4 E-Hybrid

 

The third party battery maker, Kreisel Electric also uses only one type of cell to make its modules. In this case 18650 cylindrical cells. This makes replacing the cell supplier or start using a new more energy dense cell a lot easier.

The same applies to Tesla Motors, that always use the same tiny cells in every electric car battery they make. But in Tesla Motors and Kreisel Electric cases, they only make batteries for BEVs, so they don’t need to compromise both power and energy densities. They clearly favor energy density.

 

In this field the Renault-Nissan Alliance can do a lot more to reduce costs. Sharing the same cells for Zoe’s and Leaf’s batteries should be already happening, but I guess we’ll have to wait for the 43 kWh LG Chem batteries for it to finally happen.

 

Update: this article was revised because I wrongly assumed that the new 37 Ah battery cells would be made by Volkswagen’s current supplier (Panasonic/Sanyo), but instead, these new cells are made by Samsung SDI.

 

 

More info:

https://endless-sphere.com/forums/viewtopic.php?f=14&t=79639

http://www.volkswagenag.com/content/vwcorp/info_center/en/talks_and_presentations/2014/07/FM_04_07_14.bin.html/binarystorageitem/file/06_2014-07-04+Presentation+Barclays+London+Steiger+TOP+COPY.pdf

This Post Has 12 Comments

  1. do you still think the Leaf 2017 will have this new 43 kwh battery? From what you know, will it be a battery with thermal management? (Leaf/Zoé)

    1. Yes, it will have a roughly 43 kWh battery. It still unknown if Leaf and Zoe will share the same battery, but it’s what makes sense. This is also what Carlos Ghosn has been promising for a while. Renault and Nissan sharing electric car parts to reduce costs.

      Batteries with LG Chem cells always have TMS, otherwise LG Chem wouldn’t give warranty for the cells.

      1. I prefer the e-Golf but with a new 35,8 kwh battery without TMS… it might not be enough.

    1. Hello Christian

      Yes I did. But now I’m in a process of upgrading the website server to a faster one, so I can’t focus in writing.

      It’s great to see the new 37 Ah cells coming to more VW EVs.

      1. The website seems fast enough to me. I visit frequently and never experienced a slowdown.

        Christian, from VW i never know if it’s good information or just vaporware

  2. Do you know if VAG is still pursuing this strategy? Or do they now use different cells in their BEVs versus hybrids and PHEVs? I’ve been wondering if this may explain the Audi e-tron’s very high charging rate at SoC between 50% and 85%. Although I still don’t understand why it’s rate vs SoC curve is so flat; AFAIK higher power cells are just higher power, lower energy, but they still usually have the same property of being able to charge faster (without too much damage) at low SoC. Do you know if this is incorrect…?

    1. Hi Terawatt.

      There are at least two reasons why the Audi e-Tron can charge at very high rates:

      1. A great liquid cooling system, like Tesla.
      2. Large buffer, 81 of 95 kWh means that only 85 % of the battery capacity is usable. So the real SoC should be roughly from 5 to 90 % (more buffer in the higher limit).

      “What gives? For one, Audi uses just 81.0 kWh of the e-tron’s 95.0-kWh capacity. Every automaker leaves a buffer to protect the longevity of the pack, but Audi appears characteristically conservative here.”

      https://insideevs.com/audi-e-tron-83-of-95-kwh-battery-pack/

      Using PHEV2 cells in BEVs was only a stopgap strategy, it had no future.

    2. “Do you know if VAG is still pursuing this strategy?”

      No, they are not. Because these days, the new VAG BEVs differ a lot! It’s no longer e-Up and e-Golf anymore but from e-Up to Taycan.

      New e-Up/Citigo iV comes with 60Ah cells but only 60 kW/36 kWh = 0,4C peak discharge.
      And mere 40 kW charging means about 1C quick charging. The requirement on these cells is on low price per kWh though. Cycles: 1000 cycles are enough. Here, they use hi-energy cells with with higher energy density.

      Porsche Taycan comes with 60Ah cells able to charge at 320 kW (about 3.3C for a 95 kWh pack) and 4C peak discharge. They can cost as much a the supplier wants as long as the technical requirements are met. About 1000-1500 cycles are enough as well. A mix of hi-power and hi-energy.

      PHEV cars typically need a 5C to 10C peak discharge rate and about 4000-5000 cycles. These must be hi-power cells with many cycles.

      The mild-hybrid 48V systems have yet other requirements: 30C-100C discharge (15 kW from 0,2-0,5 kWh) and even more cycles (10.000 to 25.000), achieved with supercaps coupled to the cells. These combinations of cells+supercaps need to provide very high power and very high cycle life. But only about 0,5 kWh per car. So not price sensitive per kWh.

      With the growing size and financial volume of contracts on cells/modules and many more PHEV/BEV/Mild-HE models, VAG diversified the cell chemistries for the different applications. What they do stick to: a toolkit principle for batteries with similar modules.

      MQB applications: A 12 cell module with PHEV2 size cells of the same external size can be wired as 12s1p, 6s2p or 4s3p or 3s4p.
      In current MLB applications, 13s1p-cell modules are preferably used. In prismatic cells or prismatic pouches.
      In the MEB, modules of 24 cells are used, wired in either 12s2p or 8s3p or 6s4p configuration. In prismatic cells or prismatic pouches.
      So far, they have not yet incorporated cylindrical cells (eg. 18650 or 21700) into their battery building toolkit, but this will likely follow.

      These days, PHEV2 cells refers to a dimensional *size* format, not the pure PHEV application any longer. As soon as you put a Hi-Energy cell chemistry in there, nice BEV capable cells are possible. So, there are VDA PHEV2 size cells made for BEVs (Hi-Energy chemistries). And there are VDA PHEV2 size cells for PHEV (Hi-Power chemistries).

      1. “New e-Up/Citigo iV comes with 60Ah cells but only 60 kW/36 kWh = 0,4C peak discharge.”
        Correction: This should read 60 kW/36 kWh = 1,6C peak discharge rate.

  3. Hi,
    Do you have more information about the 37AH cells from Samsung SDI?

    You have shared a lot of information about the 94AH and I am looking for the same info about the 37AH cell.

    Thank’s !

    1. Sorry Bernard but I don’t have the datasheet of the Samsung SDI 37 Ah battery cells.

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