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Do the EV measurements take into account the energy used to thermoregulate the battery during charging? They should, because there are conditions under which th
by coderenegade 3y ago
Do the EV measurements take into account the energy used to thermoregulate the battery during charging? They should, because there are conditions under which the battery won't charge at all, in which case the efficiency goes to zero.
- mort96 3y agoI can't imagine there's a lot of extra energy going to heat up the battery while charging? I'd guess the waste heat does the job everywhere except the very coldest climates.
- Rebelgecko 3y agoIt can be an issue if you're charging at like 6amps and it's way below freezing
- imtringued 3y agoThat doesn't result in zero energy efficiency. The energy efficiency is only zero when the heating is insufficient and then it is not the energy that you are putting into he battery that is the problem but the energy needed to keep it warm.
- coderenegade 3y agoThe energy required for charging is the energy input required to fill the battery, plus whatever additional energy is needed to condition the battery. If 50% of the energy you use for charging (which you pay for) goes towards conditioning the battery, then then the energy efficiency of the vehicle is 50% times whatever efficiency you get through the drivetrain. When it gets cold enough, all of the energy draw goes towards conditioning the battery, so the car doesn't charge at all. Since none of the input energy goes towards moving the vehicle, the efficiency is zero, though if you wait long enough it'll take a low value as the temperature increases and the vehicle begins to take charge. It's probably more correct to say that the energy efficiency of the vehicle approaches zero as the temperature drops. This is different to a standard car, because losses during refueling are negligible, but losses in the drivetrain obviously aren't. And of course for both types of vehicle you have additional upstream effects, e.g. production and transportation of fuel versus production of electricity, production of the vehicle, etc. The reason I raised the issue is because I hear a lot about well-to-wheels efficiency of BEVs, but I've never heard anyone take into account the effect that conditioning the battery has in certain climates. It's one thing to say that the well-to-wheels efficiency of a BEV is around 60% compared to 16% for ICEVs, but if you're neglecting a large multiplicative efficiency hit in your chain, things like hybrid electric vehicles suddenly compare a lot more favorably. And if you're comparing mileage on the basis of miles per gallon using energy input at a pump or cable that you paid for, it seems like a reasonable question to ask. Is that mpg figure calculated using the energy of the battery, or the energy that was paid for?
- Retric 3y agoConditioning the battery isn’t a year round thing 20% more energy for 2 months a year is 1.7% efficiency loss across the full year. It’s also zero in a heated garage. But again, as soon as you move up the chain on one car you need to move up the chain on the other or you’ll get as distorted picture of the tradeoffs.
- coderenegade 3y agoI acknowledged upstream effects, but this is specifically about accurately accounting for the energy input required to run the car. If I purchase X units of energy, whether it be in the form of fuel or electricity, how much of that energy is actually going into the battery, and how is it affected by climate? It's one thing to get an answer from California where it doesn't really get cold, quite another if you rely on on-street parking in, say, New York.
- Retric 3y agoIt’s still dramatically in favor of EV’s. NYC doesn’t really get cold enough to matter, average temperatures in January are above freezing. So you’re really talking about a subset of unusually cold days where it’s even slightly an issue.
- dv_dt 3y agoYou must mean in very cold conditions, where gas vehicles also often have engine block heaters plugged in so you can start them?
- idiotsecant 3y agoThose are a 'nice to have' but not a 'have to have' until it gets below -15 to -20f, which is unusual, at least in continental US.
- TylerE 3y agoThey're near, if not actually, universal in places like Canada and Scandinavia. Not exactly tiny markets.
- Xylakant 3y agoCanada has roughly 40 million inhabitants, Scandinavia (if you include Finland) less than 30 million. Even combined, that is pretty much exactly the population of France alone, or about 15 million less than Germany alone - and neither of those is exactly a huge country. Canada and Scandinavia, on the global scale, are small markets.
- ben_w 3y agoCanada is 0.481% of the world population. https://www.wolframalpha.com/input?i=canada+population+%2F+world+population https://www.wolframalpha.com/input?i=canada+population+%2F+w...
- Retric 3y agoThat’s not directly relevant in terms of energy density. We can do an apples to apples comparison for the full lifecycle efficiency, but here gas comes off even worse. Extracting, transporting, manufacturing, and distributing gas takes quite a lot of energy. ~30-50% of gas CO2 emissions occur before you burn it though exact number depends on the specific source etc. But what we care about is vehicle ranges etc not this wider picture.
- b112 3y agoSonwhat you're saying, is that by stifling and restricting local oil drilling, and refining -> gas, we're hurting the environment. A lot.
- Retric 3y agoBeing local isn’t particularly relevant because there is such a wide range of transportation efficiency and different crude oil supplies involve differing amounts of flaring etc.
- b112 3y agoAll the oil currently known, is going to be extracted. Any other concept is, I think, fantasy. Thus, local is better.
- Retric 3y agoThere’s a great deal of oil that can’t be extracted for less than it costs to synthesize it. A deepwater oil rig isn’t going to sit around a well producing 1 barrel of oil a month. So being local is again basically meaningless here.
- b112 3y agoNow now, that's not relevant, and you know it. Naturally I am referring to what can be extracted economically.
- deleted 3y ago[deleted]