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Old 04-14-2017, 08:10 AM
AdamAnDrone AdamAnDrone is offline
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Default Is this info accurate?

I found a chart on this page.

http://www.evsource.com/tls_warp11.php

It compares various motors to the vehicle weights they can reliably move. It assumes that there is no transmission. Is this information accurate? If so, this could be a helpful resource. I'll attach a picture of the chart, too.
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Old 04-14-2017, 01:52 PM
brian_ brian_ is offline
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Default Re: Is this info accurate?

It makes some sense to me... but it needs more qualifications.

The assumption that there is no transmission really means that there is only a single-speed transmission system, so the ratio of wheel speed to motor speed is constant. That limits performance, because the ratio must allow the vehicle to move at its highest speed without exceeding the motor's maximum speed, and that same ratio is used at low speed. More gear reduction would allow the motor to produce more power and torque at low speed, but would not allow use at high speed.

For the vehicle mass guideline to make sense, it must also be accompanied by a top speed assumption. Any of the motors could be used with a much heavier vehicle - by selecting more gear reduction - if they never need to go very fast. Similarly, if you're building a high-speed race car, you will need taller gearing and will not be able to move as heavy a vehicle.

There is also some assumption of performance. The more acceleration you expect, the more peak motor power throughout the speed range you need for the same mass of vehicle; the higher the top speed you expect, the more continuous motor power at high speed you need. This says that a WarP 9 is good for a 1633 kg (3600 pound) car... but I'm absolutely sure that I would not be satisfied with the performance of my compact car (which has a 160 hp gasoline engine) with only 20 hp available at normal driving speed, and it's only 80% of that weight with me in it. Even the WarP 11 - supposedly good for two tonnes (4400 lb) - wouldn't be adequate for me.
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Old 04-14-2017, 02:46 PM
brian_ brian_ is offline
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Default Re: Is this info accurate?

To put things in perspective, the Nissan Leaf is a compact car with low expectations of performance (by current passenger car standards) and a single-speed transmission. It's actually decent from zero to 60 mph; the performance is very good at low speed but fizzles out by highway speed. The Leaf's advanced AC permanent magnet motor has better torque-speed characteristics than a brushed DC motor, and a peak output of 107 horsepower (more than double the WarP 11) and (perhaps at a different speed) 187 pound-feet of torque (much more than the WarP 11), with a weight with passengers well under two tonnes (4400 pounds).

Does it seems reasonable that a WarP 11 would be acceptable in a Leaf? Whether it would be acceptable in your vehicle depends on what you expect for performance. Also remember that the mass of passengers, cargo, and trailer need to be included as well. Adam, if this is for your truck with trailer, you need to be planning on all of that mass... and so you need a WarP 13 by their table.
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Old 04-14-2017, 09:14 PM
AdamAnDrone AdamAnDrone is offline
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Quote:
Originally Posted by brian_ View Post
To put things in perspective, the Nissan Leaf is a compact car with low expectations of performance (by current passenger car standards) and a single-speed transmission. It's actually decent from zero to 60 mph; the performance is very good at low speed but fizzles out by highway speed. The Leaf's advanced AC permanent magnet motor has better torque-speed characteristics than a brushed DC motor, and a peak output of 107 horsepower (more than double the WarP 11) and (perhaps at a different speed) 187 pound-feet of torque (much more than the WarP 11), with a weight with passengers well under two tonnes (4400 pounds).

Does it seems reasonable that a WarP 11 would be acceptable in a Leaf? Whether it would be acceptable in your vehicle depends on what you expect for performance. Also remember that the mass of passengers, cargo, and trailer need to be included as well. Adam, if this is for your truck with trailer, you need to be planning on all of that mass... and so you need a WarP 13 by their table.

It is for the truck, actually. According to my original idea and according to this chart two warp 11s could give a 4000lb truck a safe 4000lb tow capacity, but man is that a lot of motor. However, after more consideration I am now considering a plug-in paralell hybrid instead. The series system is cool, but not practical. The gas to electricity conversion is not efficient enough from what I can gather. You would also run into problems pulling high continuous load from a motor when towing.

Maybe a 1/2 ton truck with an inline-6 diesel and a brushless motor would be the best system. The idea is it will be able to drive with the electric motor for about 50 miles with absolutely no wear to the transmission or the engine, enough to completely cover almost anyones daily commute. Then when towing the engine can be used and the motor can act as a sort of jake brake to recover energy and help stop the heavy load and also help accelerate the truck and trailer. Also the motor can use regen braking when driving far on the engine to increase efficiency even more. I'm interested to know what you think of this vs. a series system? PM me if you like.
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Old 04-14-2017, 09:24 PM
AdamAnDrone AdamAnDrone is offline
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Quote:
Originally Posted by brian_ View Post
It makes some sense to me... but it needs more qualifications.

The assumption that there is no transmission really means that there is only a single-speed transmission system, so the ratio of wheel speed to motor speed is constant. That limits performance, because the ratio must allow the vehicle to move at its highest speed without exceeding the motor's maximum speed, and that same ratio is used at low speed. More gear reduction would allow the motor to produce more power and torque at low speed, but would not allow use at high speed.

For the vehicle mass guideline to make sense, it must also be accompanied by a top speed assumption. Any of the motors could be used with a much heavier vehicle - by selecting more gear reduction - if they never need to go very fast. Similarly, if you're building a high-speed race car, you will need taller gearing and will not be able to move as heavy a vehicle.

There is also some assumption of performance. The more acceleration you expect, the more peak motor power throughout the speed range you need for the same mass of vehicle; the higher the top speed you expect, the more continuous motor power at high speed you need. This says that a WarP 9 is good for a 1633 kg (3600 pound) car... but I'm absolutely sure that I would not be satisfied with the performance of my compact car (which has a 160 hp gasoline engine) with only 20 hp available at normal driving speed, and it's only 80% of that weight with me in it. Even the WarP 11 - supposedly good for two tonnes (4400 lb) - wouldn't be adequate for me.
You are right. I didn't think about what speed these vehicles were meant to be going. It could be that they are geared to top out at 20mph for all we know. If they assumed a top speed of 100mph in a 4400lb vehicle with a warp11 that could mean if you only wanted to go 50mph your vehicle could weigh 8800lbs. Without knowing the speed they intended the vehicles to go at max motor rpm we can't learn anything from this chart.
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Old 04-14-2017, 11:56 PM
brian_ brian_ is offline
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Default Re: Is this info accurate?

Quote:
Originally Posted by AdamAnDrone View Post
It is for the truck, actually. According to my original idea and according to this chart two warp 11s could give a 4000lb truck a safe 4000lb tow capacity, but man is that a lot of motor.
That makes sense... and I agree. A DC motor with commutator like this is bulky and heavy... which is why modern commercially-produced EVs and hybrid vehicles don't use them. Unfortunately, even AC induction motors (such as the often-mentioned AC-51) are considered too expensive by most builders, and even they are heavy and bulky compared to the permanent magnet AC motors in modern use.

Quote:
Originally Posted by AdamAnDrone View Post
However, after more consideration I am now considering a plug-in paralell hybrid instead. The series system is cool, but not practical. The gas to electricity conversion is not efficient enough from what I can gather. You would also run into problems pulling high continuous load from a motor when towing.
The parallel configuration certainly helps the efficiency, and when power bypasses the electric components it doesn't cause overheating problems in them.

Quote:
Originally Posted by AdamAnDrone View Post
Maybe a 1/2 ton truck with an inline-6 diesel and a brushless motor would be the best system. The idea is it will be able to drive with the electric motor for about 50 miles with absolutely no wear to the transmission or the engine, enough to completely cover almost anyones daily commute. Then when towing the engine can be used and the motor can act as a sort of jake brake to recover energy and help stop the heavy load and also help accelerate the truck and trailer. Also the motor can use regen braking when driving far on the engine to increase efficiency even more. I'm interested to know what you think of this vs. a series system? PM me if you like.
I agree that electric-only mode would need to be only when not towing or heavily loaded, and I agree that Regenerative Braking is useful when loaded (both for varying speed, and for descending and then climbing grades).

I think with anything other than PM AC motor-generators, series doesn't make sense for normal applications. With the best hardware, series still only makes sense if EV mode operation is important... but then it can be a good solution.
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