# How do electric motors overcome limited hp and torque to provide good performance?



## fesodes (Apr 18, 2011)

I've been doing some research on plug-in hybrids and EVs. Of the advantages they had, one of them is good acceleration. What I don't get is, how can PHEVs and EVs excel in this area when they lag combustion engines in horse power, torque and weight? 

Doing a quick search, a 2007 Camry 2.4L engine pushes out 158hp and 161 lb ft of torque. Where as a Warp 9 according to info I found on this site can provide 145 KW with a 36KW pack of Calb batteries weighing about 350KG. 

I do understand that electric motors get instant torque but is that factor alone capable of outweighing all the negatives like having to carry heavy batteries and having less horse power and torque?

Thanks


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## Coulomb (Apr 22, 2009)

fesodes said:


> Doing a quick search, a 2007 Camry 2.4L engine pushes out 158hp and 161 lb ft of torque. Where as a Warp 9 according to info I found on this site can provide 145 KW with a 36KW pack of Calb batteries weighing about 350KG.


 For a start, 158 hp is only 118 kW. The battery pack would be 36 kWh, and capable of well over 100 kW for a short time. 36 kWh is quite a large pack; smaller packs can easily deliver 200 kW or more for short periods of time. I don't think in terms of foot pounds, but I'm pretty sure that a Warp motor with the right controller and pack can easily exceed the torque of a 2.4 L ICE, and it will do it from zero RPM till you run out of voltage.


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## tomofreno (Mar 3, 2009)

The 9" ADC motor, which is similar to a Warp9 in terms of torque and power output has about 160 ft-lb (118 N-m) and 83 H.P. (62kW) at 660A (144V pack) according to the graph I have from ADC. But as you said, that torque is available immediately, unlike an ice that has to rev up in rpm to give its maximum torque. Shaft power is proportional to the product of torque and rpm, so high power is not required to have high torque at lower rpm. It is torque that does work (product of torque and shaft rotation angle) to turn the wheels. Power is the rate of work, work/time, which isn't that large until the wheels get spinning faster and the car starts moving faster, even though the torque and work are high. So the ev jumps off the starting line faster due to higher starting torque. The ice may well accelerate faster at higher vehicle speeds if it has higher power, but the ev is already ahead. If the race is long enough at high enough vehicle speed the ice will catch up and win, but it takes time to for it to catch up. The max power output of an electric motor increases with higher pack voltage. You need both high voltage and high current to get high power output from an ev. Torque will drop quickly with increasing rpm with a low voltage pack, resulting in low shaft power. An ice will never catch an ev with the same max power, since the ev will jump faster off the starting line and maintain that lead since they both can do the same work/time at higher vehicle speed and rpm.


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## piotrsko (Dec 9, 2007)

my $.02 here: If you look at the HP vs torque charts of your favorite Ice motor, especially the 4 banger versions, you will note that ICE does not make much torque at idle (15 hp & perhaps 25 ft lbs). At 2000 rpm, most 4 bangers make only about 50 hp and perhaps 75 ft lbs torque. The EV does not have to work all that hard to beat these low values. For example at 2000 rpm I should have 33 hp and looks like 65 ft lbs torque.


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## JRoque (Mar 9, 2010)

Hi. Jack Rickard of EVTV tested a Warp9 motor driven by a Soliton1 controller and got 157 Horsepower and 277 ft-lbs (3200 RPM) at the wheel, measured at a dynamometer. I believe they calculated a 0-60 MPH in the sub 7 second region.

These numbers are not input power as shown for the Camry, they are output at the wheel. Those 277 ft-lbs of torque are available from zero RPM and would smoke the Camry getting off the line.

JR


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## Bowser330 (Jun 15, 2008)

JRoque said:


> Hi. Jack Rickard of EVTV tested a Warp9 motor driven by a Soliton1 controller and got 157 Horsepower and 277 ft-lbs (3200 RPM) at the wheel, measured at a dynamometer. I believe they calculated a 0-60 MPH in the sub 7 second region.
> 
> These numbers are not input power as shown for the Camry, they are output at the wheel. Those 277 ft-lbs of torque are available from zero RPM and would smoke the Camry getting off the line.
> 
> JR


Do you know what the voltage was? 
Are you saying the peak whp was @ 3200rpm?
Sub 7 second 0-60 in what car? what was the weight? link to where you saw this please, thanks.


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## JRoque (Mar 9, 2010)

Hi. See here: http://jackrickard.blogspot.com/2011/04/graphs-is-always-greener.html

JR


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## Bowser330 (Jun 15, 2008)

JRoque said:


> Hi. See here: http://jackrickard.blogspot.com/2011/04/graphs-is-always-greener.html
> 
> JR


Thank you for the link.

But your sub 7 sec 0-60 was on his third gear pull 

If you take a look at the second gear pull, he goes from 0-57mph in 5.13 seconds!

any with a combination of 2nd + 3rd it might be even faster....of course this is in a super lightweight kit car...


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## drgrieve (Apr 14, 2011)

You should note that Jack and co did these tests from a rolling start - the tests were to look at the curves not a 0-60 time.


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## JRoque (Mar 9, 2010)

Hi. That's one big graph up there... or at least it looks that in my browser.

Yeah the car is pretty quick for any car but the fact that it's electric and got there at a relatively low cost says something, doesn't it?

The sub 7 sec 0-60 came from one of their videos. If I remember correctly they were testing all of their cars on the road, not just on a dyno. They also did a circuit race video which I found most interesting in that the AC-50 (motor/controller) car was the fastest of Jack's car.

JR


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## Bowser330 (Jun 15, 2008)

JRoque said:


> Hi. That's one big graph up there... or at least it looks that in my browser.
> 
> Yeah the car is pretty quick for any car but the fact that it's electric and got there at a relatively low cost says something, doesn't it?
> 
> ...


sorry for the picture, i dont know how to resize pictures in HTML code

the ac-50 was the fastest around the circuit? Does he have a list of the motor+controller combos he tested?

If he was going up against the DC combo in the graph, the ac-50 is 3X underpowered!

150hp 280ftlbs
50hp 100ftlbs


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## rwaudio (May 22, 2008)

You have to take jacks results in context. His idea of a "powerful" car is loading it up with more and more batteries to get the voltage he's looking for using 180ah cells. (this makes for a fairly heavy car when you consider the goal as performance)

My idea of a powerful car is using higher C rate batteries and add enough of them for the voltage and range you need (not want) this is a 40-80ah pack... 

I see jack as somewhat blind and stubborn when it comes to performance with his latest build (Cobra) he's doing what Crodriver started with.... lightweight car and some thundersky's.... Crodriver evolved to headways then A123's. Jack should learn from others and skipped step 1 and 2 and gone straight to an A123 type cell. Sure it's more expensive, but look at the Cobra, it's a COBRA not a "insert cheap/slow car here".

ICE can be powerful and fast, EV's can be powerful and fast, it comes down to design criteria and price not the choice of ICE/EV.


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## DIYguy (Sep 18, 2008)

rwaudio said:


> You have to take jacks results in context. His idea of a "powerful" car is loading it up with more and more batteries to get the voltage he's looking for using 180ah cells. (this makes for a fairly heavy car when you consider the goal as performance)
> 
> My idea of a powerful car is using higher C rate batteries and add enough of them for the voltage and range you need (not want) this is a 40-80ah pack...
> 
> ...


Ya, I've been thinking the same thing. I just see the Cobra with Li-poly. Wrong battery for performance....it's no wonder he is running out of space to put the bricks.


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