Does size matter?

I was watching a YouTube video the other day and it got me thinking. Is there an incorrect focus on battery capacity? Should the focus be more on the efficiency of the EV? I don’t know of anyone who went to buy a fossil car who asked “How big is the fuel tank?”. On the other hand, I do know a lot who ask “What is the l/100Km (mpg)?”. Come to think of it, I can’t recall ever asking “How far can I drive on a full tank?” either. 

There is a fundamental problem here. Consumers, and dealers, are fixated on battery capacity instead of the more important efficiency of the car. Think of the Tesla Model S for a moment. P60, P75, P90, P100. All based on battery capacity. Yet the Tesla isn’t really so efficient, I think somewhere over 22kWh/100Km. Imagine if you went into a fossil car showroom and they said, “This SUV has a 60ltr tank, or you can have this one with a 100ltr”  then you go down the road and the dealer says there “This city car has a 34ltr tank” and you never asked how much fuel it actually used. Maybe the SUV is using 15ltr/100Km, and the city car is using 7ltr/100km. Which is really better when you consider all factors, such as cost of fuel in addition to range? 

My Ioniq has a usable battery capacity of 28kWh, I understand there is actually more, but its a sort of buffer/reserve. This is currently giving me a range of about 200Km, and then with a rapid charger I can refill in 20 minutes or so, depending on charge level, to 94%.  In comparison, the new Nissan Leaf has a 40kWh and according to the Nissan Germany website a consumption of 20.6kWh/100Km. (I will say here I am surprised it is so much, I had expected more in the region of 16kWh/100Km). Ignoring the reduced charging times due to non-existent thermal management, the Leaf takes 40-60 minutes to reach 80% after an official 415 km on from a full charge (again according to the Nissan Germany website). The website does say its possible to charge to 100% at normal speed. So a bit of simplified maths, to cover 800Km at 100Kmh.

Leaf = 8hrs driving @100Kmh +  2 x 60 minutes charging (Total 10hrs)
400km on the initial charge, then 2 charges of 80% (320Km) to reach destination

Ioniq = 8hrs driving @100Kmh + 4 x 20 minutes charging (Total 9hrs 20mins)
200km on the initial charge, then 4 charges of 94% (188Km) to reach destination

Now, before anyone says anything, yes these figures are unrealistic as for the last charge it wouldn’t be really required for the Leaf to charge to 80% but I am ignoring the Leafs reduced charge rates of only 14Kw with a hot battery. Also I took the WLTP range for the Leaf, not a real world value, and for the Ioniq I took the range shown on my car a few days ago, rather than the (unavailable) WLTP value. The calculations also take no account for breaks or whatever, but the point is, even with a smaller battery and more stops, the better efficiency makes a real difference.

So returning to my original point, shouldn’t we be focusing on efficiency when talking about EV’s and not the capacity of the battery?

The second area that also needs to be addressed is charging rate. The Ioniq can charge at up to 70Kw, the Tesla Supercharger up to 120Kw the Leaf and Ampera-e up to 50Kw and the Zoe up to 43Kw. Sounds good in principle. Realistically the Ampera-e and Leaf charge a lot slower, I am sure I read the e-Golf tops out at about 40Kw. The Zoe can charge at up to 43Kw 400V three phase AC 63A. However, at least where I live, most Type 2 chargers are 240V AC three phase 32A or 22Kw.

Charger speeds are increasing however. When you look at the next generation 350Kw rapid chargers from Ionity it is clear that in the future charging will be quicker. Lets hoe they install enough chargers. It is already an issue with cars blocking the chargers, EV that are not charging or have completed charging, or fossil cars that are just parked in EV charging bays. I do sometimes worry if the next generation Porsche Mission E cars will use the rapid chargers as personal parking spaces.

Categorised as General

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