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Old 03-06-2016, 09:22 PM   #31 (permalink)
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For that money I'd buy one and I don't need another car. I know what you mean about running out of steam working on cars.

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Old 03-07-2016, 12:47 AM   #32 (permalink)
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All that work is why my Plans A & B are ordered the way they are. But the Toyo-Lexus into VW swap needs to be done, if only to blaze the trail. It's good to have a Plan B.

The EVTV folk bought a wrecked Kia Soul EV to scavenge the battery pack for a Tesla powered AC Cobra. But it only had a dead 12v battery, and that left them with a driveable wreck they didn't want to take the battery pack out of. I forget what they paid, maybe $3K?
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Old 03-07-2016, 02:35 AM   #33 (permalink)
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Quote:
Originally Posted by Old Mechanic View Post
I know what you mean about running out of steam working on cars.
People talk about total cost of ownership. I'd like to see TCO in hours, not dollar amounts. If a guy makes $10, $15, $20 or more dollars per hour, how many hours to own a Leaf or Mirage or whatever? And how many hours to build a VW EV conversion Beetle?

Personally I love working on cars. But I love doing other things too. And it's getting to where the other things are out weighing the mechanickin'.

Last edited by Isaac Zackary; 03-07-2016 at 08:28 AM..
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Old 03-07-2016, 06:30 PM   #34 (permalink)
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Woohoo! My day just got better!

In reference to the original post, I started pricing rentals again. The problem I had was that I was afraid to not go with the damage waiver. I've personally known an individual who rented a car without it and then wrecked the car and had to pay for it out of his own pocket. But in looking at my credit card benefits it says right here that it offers rental car insurance! That makes me happy because it just cut the cost of renting a car in half! I can now rent a car for less than $50 per day (total, except fuel). For the amount of long distance driving I do, that would pay for itself with the lack of insurance and maintenance of a second vehicle! So owning just an electric vehicle (instead of three ICE vehicles) is totally doable!
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Old 03-13-2016, 10:19 PM   #35 (permalink)
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Ok. So here's a dumb question. In thinking about the Leaf I'm going to get, I wanted to see what I could do to make it more efficient so as to drive further. My first thought was aeromods or just driving a lot slower in order to reduce air drag. But first I thought I should calculate how much is actually lost due to aerodynamic drag.

This is what I got:

Cd = 0.29
A = .725m^2
P (density of air)= 1.225
100km = 27.7778m/s

Cd x A x P x 27.778^2 x 0.5 = 99.36584N
Cd x A x P x 27.778^3 x 0.5 = 2760.162W

According to that, if there were no rolling resistance, I should be able to drive for 8.6 hours at 100km per hour, or over 860km/540miles.

So does that mean that at 100kph about 15% of the friction/loss, whatever you want to call it, on a Leaf is air drag and the other 85% is a combination of rolling resistance and battery/controller/motor inefficiencies?
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Old 03-13-2016, 11:45 PM   #36 (permalink)
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Aero drag is listed as being 70% of the total resistance forces at 70 mph, 30% at 30 mph.

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mech
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Old 03-13-2016, 11:53 PM   #37 (permalink)
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Originally Posted by Old Mechanic View Post
Aero drag is listed as being 70% of the total resistance forces at 70 mph, 30% at 30 mph.

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That's what I thought. But it doesn't matter how many times I check my math. With that kind of air drag the Leaf should go much further than 100 miles. As much as 5 times further .

Simply a couple of kilowatts at 100kph is nothing. I'd expect more like 10. Maybe I'm doing the math wrong, but I can't see where.

Math aside, it would seem to me that a boat tail, wheel skirts and some air dams in front of the wheels along with some slower-than-usual driving ought to double the current range.

Edit:

I see where I made the mistake. I used a CdA number instead of actual area. The no way a Leaf is going to have a frontal area of .7m^2. It's 2.2297m^2. So it takes about 8.5kW just to push the Leaf through the air at 100kph. I'd like to see what kind of Cd is possible on a Leaf with mods. But for now, I'm glad I figured it out.

Last edited by Isaac Zackary; 03-14-2016 at 05:04 AM.. Reason: fixed wrong number
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Old 03-14-2016, 03:35 AM   #38 (permalink)
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Your calculations should include vehicle weight. See here: Your Mileage May Vary... - EVTV Motor Verks


Quote:
And so we came up with a rule of thumb. And that rule, based on just our own outcomes, was that for every 10 lbs of car, it will require 1 Watt hour of energy to cover 1 mile of travel.
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Old 03-14-2016, 06:25 AM   #39 (permalink)
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Your calculations should include vehicle weight. See here: Your Mileage May Vary... - EVTV Motor Verks

I was working towards it.

With the following I'm assuming the Nissan Leaf has a full 24kW/h total capacity and an 80% efficient motor at it's maximum GVWR of 1902kg.

Air drag on an average day at sea level (but I'm at 7,800ft!) absorbs 8.45kW at 100kph/62mph.

I just guessed at an average rolling resistance being 130N or 3.61kW. Obviously road and tire conditions will dramatically change that.

The combination would be only 12,1kW (Not Bad imo!) and would be able to drive the Leaf 159km or 99mi at speeds of 100kph/62mph.

Ah, but the weight! Figuring initial acceleration (but isn't there an ending deceleration too that we're not accounting for?) it would consume 0.408kWh to reach 100kph/62mph, which knocks off about 5 km or 3mi of total usable distance to 155km or 96mi. But that's assuming you then maintain a steady speed after initial acceleration (no rock slides or avalanches to stop for).

However, here where I live I have to climb 1,310m/4,300ft (7,800ft to 11,000ft) up a mountain in order to get out of town. That would consume 7.2kW/h and put total distance to 99km/62mi (the top of the mountain is only 43 miles from here), which if I can make it to the top of the mountain, I can coast (or regen) down the other side to the next town and recharge there before heading to the big city. Sound's like it's actually possible.



The benefit of analizing every side to the whole story is that I can then figure out how to go about modding if I ever did get to it. For an example, I can see that if I shaved off the Cd to 0.19 by boat tailing and what-not then I'd gain 20 to 30 miles of range. Or if this planned route over the mountain with as little weight in the car as possible then I'd gain about 7 miles.

Last edited by Isaac Zackary; 03-14-2016 at 06:32 AM..
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Old 03-14-2016, 12:57 PM   #40 (permalink)
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The cited article makes the case that watt-hour/mile is a better unit to work with than kilowatt-hours/100 miles.

From the chart, the Leaf weighs 3276lb, and gets 300 watt-hours per mile; a ratio of 11 to 1.

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