this post was submitted on 23 Dec 2023
57 points (93.8% liked)
Canada
7185 readers
479 users here now
What's going on Canada?
Communities
🍁 Meta
🗺️ Provinces / Territories
- Alberta
- British Columbia
- Manitoba
- New Brunswick
- Newfoundland and Labrador
- Northwest Territories
- Nova Scotia
- Nunavut
- Ontario
- Prince Edward Island
- Quebec
- Saskatchewan
- Yukon
🏙️ Cities / Local Communities
- Calgary (AB)
- Edmonton (AB)
- Greater Sudbury (ON)
- Halifax (NS)
- Hamilton (ON)
- Kootenays (BC)
- London (ON)
- Mississauga (ON)
- Montreal (QC)
- Nanaimo (BC)
- Oceanside (BC)
- Ottawa (ON)
- Port Alberni (BC)
- Regina (SK)
- Saskatoon (SK)
- Thunder Bay (ON)
- Toronto (ON)
- Vancouver (BC)
- Vancouver Island (BC)
- Victoria (BC)
- Waterloo (ON)
- Winnipeg (MB)
🏒 Sports
Hockey
- List of All Teams: Post on /c/hockey
- General Community: /c/Hockey
- Calgary Flames
- Edmonton Oilers
- Montréal Canadiens
- Ottawa Senators
- Toronto Maple Leafs
- Vancouver Canucks
- Winnipeg Jets
Football (NFL)
- List of All Teams:
unknown
Football (CFL)
- List of All Teams:
unknown
Baseball
- List of All Teams:
unknown
- Toronto Blue Jays
Basketball
- List of All Teams:
unknown
- Toronto Raptors
Soccer
- List of All Teams:
unknown
- General Community: /c/CanadaSoccer
- Toronto FC
💻 Universities
💵 Finance / Shopping
- Personal Finance Canada
- BAPCSalesCanada
- Canadian Investor
- Buy Canadian
- Quebec Finance
- Churning Canada
🗣️ Politics
- Canada Politics
- General:
- By Province:
🍁 Social and Culture
Rules
Reminder that the rules for lemmy.ca also apply here. See the sidebar on the homepage:
founded 3 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Not sure I believe that. It takes less energy to keep a vehicle moving than it does to accelerate it. That’s not going to change whether it’s gas or electric.
No, EVs are not perfect and I’m not saying I have the answers, but it’s amazing how some people are so ready to throw in the towel when one thing doesn’t work out.
Merry Christmas, it's physics time. When a vehicle is in motion, the forces the motors must fight are governed by the following equations: F~total~= F~drag~ + F~rolling~= 0.5ρv^2^C~D~A + Nμ~R~ , where:
If we take F~total~ and multiply it by the speed of the vehicle, we find the energy wasted per second, or the power needed to maintain that speed. Filling in the blanks for a Tesla Model 3 (because it's easy to find the numbers) at 120kph (and ideal circumstances!), we find that F~total~ = 347.4 N + 196.4 N, and so P~wasted~ = 18.13 kJ/s or 18.13 kW. For a battery with 74 kWh usable, this translates to 489.8 km. Inside EVs tested their Model 3 at 112.6 kph and got 498.9 km, so this seems about right.
Now let's slow things down to 70 kph. F~total~ = 118.2 N + 196.4 N, and our range jumps to 846.7 km. That's a lot, but hypermilers have gotten more in this particular vehicle. Now, I never said the 70kph example would have stops and starts, but since you brought them up, let's see if we can recalculate with those in mind.
The energy needed to bring a vehicle up to 70 kph is the kinetic energy adjusted up for a motor's electrical efficiency, E = (1/.96)(1/2)mv^2^ = 358.4 kJ or 0.0996 kWh. The energy recuperated when using regen braking is the same, but adjusted down for the regen's electrical efficiency, E = (0.7)(1/2)mv^2^ = 240.8 kJ or 0.0669 kWh. So a single stop-start cycle uses a net 0.0327 kWh. I'll add one such 10-second start-stop cycle every 2 minutes (just spitballing), and recalculate for drag at the new speeds. We end up with an estimate of 733 km. This matches EV-database's city range estimates in mild weather.
Now, this may seem a bit startling, but the fact that EVs are more efficient in traffic than on the highway has been empirically measured. Personally, I can confirm that my range in my Clarity PHEV is about 50% longer at 45 mph than it is at 75 mph.