Posted on 5th September, 2019 |
by Guest Contributor
September 5, 2019 by Guest Contributor
by Simon Barke
Following the unveiling of the new Porsche Taycan yesterday, analysts [one hit the time] electric competitor (Tesla Model S) "ancient by comparison", citing an 800-volt punching system that "reduces recharge time." It's true that higher system voltages can reduce recharge time: you can apply more battery power without increasing the charging current. But how good is Porsche's implementation?
If you want to reduce the charging time of electric cars, you can either increase the maximum charging power, or make the vehicle more efficient. Ideally, you do both. Unfortunately, the Volkswagen Group has a known problem history with efficient vehicles. Recently, settled the case after it was discovered that Audi, Bentley, Porsche and Volkswagen cars contained illegal fraud software that increased the effectiveness of test stands. The Audi e-tron remains one of the least efficient electric cars on the market. The new Porsche doesn't fare much better. In fact, it gets a lot worse.
Based on the European WLTP test cycle, the Taycan "Turbo S" needs 111 kWh to recharge its battery, providing a total range of 256 miles. That's 2.3 miles per kWh, worse than 2.6 miles per kWh on an e-tron. Compare this to a Tesla Model S 'Performance' with a 3.3 mph WLTP efficiency and you'll see how effective large electric sports sedans can be. The Model S is even faster than the top-class Taycan, while the Taycan 'Turbo' is only marginally faster than the Tesla Model 3 'Performance', a 3.7-mph car. (Fun fact: Model 3 "Productivity" causes 40% less CO2-eq emissions during electricity production than Taycan "Turbo S.")
Poor efficiency has an adverse effect on charging speeds. As a countermeasure, Porsche has introduced an 800-volt system that can handle impressive charging power up to 270 kW. The specified recharge time of "5 to 80% in 22.5 minutes" can only be explained if Taycan manages to maintain 270 kW for at least half of the charging cycle. We can use this information to evaluate an idealized load profile under optimal conditions. When comparing this to Tesla charging profiles, the advantage of the 800-volt system becomes apparent: The Model S can maintain its maximum rating of 200 kW for the first 20-30% of the charging cycle. The same is true of the Model 3. Charge power of Model 3. (Tesla profiles are idealized curves of real data that were taken during the beta testing of Supercharger V3 and may have improved slightly since then.) 
Note that only a handful of high-speed DC chargers can provide such high power. ness. In the US, ten 250 kW kW Supercharger V3 stations are available or under construction, while all other 690 stations are still limited to 150 kW but may be upgraded in the future. Although the overall charging infrastructure of Taycan is still not so good, there are many more stations that support full charging capacity. 229 Electrified Seats in America, which can provide up to 350 kW, are in operation today, with 71 more planned by the end of the year. speed (miles of range added per hour of charging). At the same time, you can scale the condition of the charged battery (%) to the range of the vehicle (miles) when you know the total range. If you do this, you can see that the poor performance and short range of Taycan eliminates its advantage of charging power. There is only a small area where the taikan comes out from above. The Model S is faster during most of the charging cycle. Not surprisingly, the Model 3 dominates the Taycan entirely.
The calculation of actual charging times is complicated. Essentially, you need to integrate the reverse of the loading rate (the time it takes to add a range) over a specified range interval. If the battery is nearly full, the time required to add more range is significantly increased. For this reason, most manufacturers provide the time required to charge the battery up to 80% or the like. However, if you want to compare different cars, we need to calculate the time it takes to add range. Let's say you're approaching a charger with 20 miles left. How long does it take to add 80, 130, 180 or 230 miles?
While Model 3 is arguably the fastest-charging electric vehicle available so far, Taycan "Turbo S" and Model S "Performance" are actually leading the way in charging time – up to 200 miles, While the Model S continues to add more range at high speed, the Taycan is falling fast. This is no surprise: after adding a range of 230 miles, the Porsche's charge state reaches 97% and the loading speed reaches a creep. A Tesla battery provides the same range with only 67% charge, and thus can take up more power much faster.
Assumptions Notes: All figures are based on the European WLTP test cycle and idealized loading forces under optimal conditions. All loading profiles are simplified models. Taycan's charge rates are estimates based on estimated charging times. The charging speeds of Model S and Model 3 are based on early beta tests of the Supercharger V3. Tesla failed to provide official billing profiles. Porsche did not answer the question
If the Volkswagen Group wants to remain competitive, it must begin to look for efficiency. High-voltage systems and complex charging profiles are overcoming, which leads not only to more expensive cars but also to higher emissions. Is there hope? Yes. It is believed that the upcoming VW ID.3 can actually be a very efficient car. Will Porsche Taycan be Volkswagen's last step towards a cleaner future?