TimeHorse
Well-known member
- Joined
- May 13, 2010
- Messages
- 999
In this thread I started a discussion of how to calculate the power curve of the Nissan Leaf in terms of velocity / wheel angular rotation similar to the chart shown in that post from Tesla.
I am pretty confident that the power curve is a quadratic in terms of the angular velocity of the wheel and came up with the following equations:
Where a, b and c are the constants of the Power Curve I wish to calculate such that:
Where w is the angular velocity of the wheel at any given time. The problem is, I can't solve this equation without some more information. It's not necessary to do the US06 or HWFET test to fill in the gaps, though those would do it. Instead, IMHO, the easiest way to do this calculation is to set the LEAF up on a test bed, mount a dynamometer on it's wheel and run it at 2 consistent speeds for 5 minutes straight and then measure the Energy used to perform this test. Take the near-ideal speed of 20 mph / 32 km/h for the first test and 45 mph / 72 km/h for the second and please report back here so I can do a proper calculation of the expected battery life.
Okay, I've stopped my drug-induced dream and am moving back to reality. So, is there anything we can do to figure out a, b and c given all the information we currently have available? Can anyone see a way of solving this problem?
The reason I am trying to get this information is because I want to calculate the expected energy requirements and thus range based on the EPA US06 and HWFET test vectors and to do this I need to calculate the instant power for each of the velocities specified in the test suite so that I can sum them to get the total energy drain. That would allow me to compute the useful range of the LEAF under more realistic circumstances that an average of 19.6 mph in stop-and-go traffic with only 1:45 seconds or so spend on an actual highway in EPA LA4. Since my commute is mostly highway driving, the LA4 numbers aren't adequate for my understand of how the LEAF will fit into my life and I really need to know these numbers before I can buy this wonderful car.
I am pretty confident that the power curve is a quadratic in terms of the angular velocity of the wheel and came up with the following equations:
Code:
37,949.797 930 052 3 rad^2/sec^2 * a + 37,949.797 930 052 3 rad/sec * b + c - 6,437,136 Joules = 0
Where a, b and c are the constants of the Power Curve I wish to calculate such that:
Code:
P(w)[instant] = a * w^2 + b * w + c
Where w is the angular velocity of the wheel at any given time. The problem is, I can't solve this equation without some more information. It's not necessary to do the US06 or HWFET test to fill in the gaps, though those would do it. Instead, IMHO, the easiest way to do this calculation is to set the LEAF up on a test bed, mount a dynamometer on it's wheel and run it at 2 consistent speeds for 5 minutes straight and then measure the Energy used to perform this test. Take the near-ideal speed of 20 mph / 32 km/h for the first test and 45 mph / 72 km/h for the second and please report back here so I can do a proper calculation of the expected battery life.
Okay, I've stopped my drug-induced dream and am moving back to reality. So, is there anything we can do to figure out a, b and c given all the information we currently have available? Can anyone see a way of solving this problem?
The reason I am trying to get this information is because I want to calculate the expected energy requirements and thus range based on the EPA US06 and HWFET test vectors and to do this I need to calculate the instant power for each of the velocities specified in the test suite so that I can sum them to get the total energy drain. That would allow me to compute the useful range of the LEAF under more realistic circumstances that an average of 19.6 mph in stop-and-go traffic with only 1:45 seconds or so spend on an actual highway in EPA LA4. Since my commute is mostly highway driving, the LA4 numbers aren't adequate for my understand of how the LEAF will fit into my life and I really need to know these numbers before I can buy this wonderful car.