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Discussion Starter #1 (Edited)
The basic rule of thumb is that you need 50V per 1000 RPM at 1000A [after major - just to be clear, this is MOTOR CURRENT]. That decreases to around 36V/1000 RPM at 400A. The incremental voltage between those incremental currents gives you the total resistance of the system, or 14V/600A = 23.3 milliohms. [after major - this method of calculating resistance is only correct if the motor is not spinning... mea culpa.]

The 400A tests were just to get a good feel for how much iterative tweaking of dyno load and throttle would be needed to get even spacing of both torque (current) and RPM (voltage). I then doubled the dyno load so it required 800A at 2000 RPM just to get a good incremental resistance data point. Finally, I increased dyno load again so that the full 1000A of the Soliton1 was required at 2000 RPM and 3000 RPM (2050 and 3050 as measured with a contact tachometer, respectively) to get the all important ratio of voltage per 1000 RPM.

The clusters are the result of plotting all of the datapoints in the log file for each RPM and load combination.

Note that the ratio of RPM/V is not precisely linear, but the point of this post is to give people a better idea of what sort of performance to expect from a WarP-9 at currents/voltages way higher than are plotted in the official chart.
 

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The basic rule of thumb is that you need 50V per 1000 RPM at 1000A. That decreases to around 36V/1000 RPM at 400A. The incremental voltage between those incremental currents gives you the total resistance of the system, or 14V/600A = 23.3 milliohms.
Hi Tesser,

I don't believe this calculated resistance is accurate. Although the motor is likely into saturation at 400A, there will be some increase in flux from 400 to 1000A, therefore an increase in generated voltage. The method you have used for resistance calculation is only valid at stall where the Eg = zero.

Should you specify "motor" current for those who may assume otherwise?

I do enjoy your graph, and data :)

Regards,

major
 

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Discussion Starter #3
...The method you have used for resistance calculation is only valid at stall where the Eg = zero.
Yep. In retrospect that was totally obvious. I thought the calculated resistance seemed reasonable for the motor + cables and didn't give it much additional thought. I added some comments to my original post to correct it without removing the incorrect parts.


Should you specify "motor" current for those who may assume otherwise?

I do enjoy your graph, and data :)
You know exactly why I did this, don't you? :rolleyes:

Next I'll try to figure out when the WarP-9 goes into saturation. My plan is to hold the RPM constant (at, say, 2500 RPM) while increasing dyno load such that motor current increases in, say, 100A increments.

Sound reasonable? IIRC you once stated that many motors are approaching saturation at their S2-60 current rating... Correct or no?
 

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You know exactly why I did this, don't you? :rolleyes:
To show off your 1000A controller :)
Next I'll try to figure out when the WarP-9 goes into saturation. My plan is to hold the RPM constant (at, say, 2500 RPM) while increasing dyno load such that motor current increases in, say, 100A increments.

Sound reasonable?
Not the usual motor test curve, but would yield interesting data, so reasonable? Sure.

IIRC you once stated that many motors are approaching saturation at their S2-60 current rating... Correct or no?
For a series wound, class H, vented fan cooled motor, yeah, kind of, probably, maybe, wouldn't bet my house on it, but for the lack of better data, sure why not?

But you are correct, I did say that ;)
 
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What does it all mean when it's in a car and your going pedal to the metal? Won't the Soliton1 do better than 1K. Question, when you do your bench testing and you hit your motor limit of 1K what is your battery current output? It should be at or near the same if the duty cycle is at or near 100%. Can you show that? Will you?
 

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Discussion Starter #8
What does it all mean when it's in a car and your going pedal to the metal?
Depends what the RPM of the motor is, simple as that. The throttle controls motor torque, not motor power, in a Soliton1 (same as pretty much every other controller for EVs). Our vehicles would be damn near undriveable if anything besides torque control was used.

Won't the Soliton1 do better than 1K.
No. Why would you expect a 1000A controller to deliver more than 1000A?

Question, when you do your bench testing and you hit your motor limit of 1K what is your battery current output?
As above, it depends on the motor RPM and the battery pack voltage. The controller adjusts the duty cycle as needed to maintain a desired motor current (ie - pulling power, or torque) regardless of motor RPM, up until the point at which motor voltage = battery voltage. If RPM continues climbing from that point on then current must drop a corresponding amount. There is no escaping this reality any more than putting a windmill on my car won't recharge my battery pack while driving.

It should be at or near the same if the duty cycle is at or near 100%. Can you show that? Will you?
Correct, battery current = motor current at 100% duty cycle, and we HAVE shown that, Pete. We are pretty much the ONLY people that have ever shown that. Do you see dyno charts from any other controller manufacturer here on this forum, or any other for that matter?
 

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Discussion Starter #10 (Edited)
It appears that the WarP-9 goes into saturation (changes over from torque being proportional to the square of current to being linear) at 400A. The direct pressure readings from our hydraulic dyno:

200A 1014 rpm 24.7V <200 psi <- too low to read on gauge
250A 1010 rpm 28.7V 325 psi
300A 1010 rpm 31.6V 500 psi
350A 1015 rpm 34.4V 625 psi
400A 1008 rpm 37.6V 850 psi
450A 1015 rpm 39.0V 900 psi

(HP = RPM x PSI x 0.0000182)

I couldn't hold ~1000 rpm at 500A with the dyno set to maximum load but the change in psi per 50A increment has already dropped radically so I feel pretty good about the results.
 

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You know exactly why I did this, don't you? :rolleyes:
I do. It shows that the Warp 9, and likely pretty much any series DC requires a very high battery voltage to get the RPM needed for 1000 amps of battery current to be matched. It seems it could possibly be enough to add another to your count of motors versus Soliton's. I only recently realized that a large portion of the EV community doesn't understand the dynamics of back EMF and the relationship of motor voltage and motor current being different than battery current. Oh well, its something that will be understood soon enough.

I am very interested at what you find the amperage saturation point of the Warp 9 to be at. Would this be the most efficient point of operation, or would RPM/voltage be a larger factor? I'm looking to operate at the most efficient point possible when I complete my conversion and am thinking that the Warp 9 might be too big for a highway cruising ~2500 pound car to get maximum efficiency but I could be wrong, I'm not sure on the specifics of efficiency and its what I'm trying to figure out right now. I wouldn't mind flying down the road with a bigger motor than I need though and it seems the differences may be negligible.
 

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Discussion Starter #12
...I only recently realized that a large portion of the EV community doesn't understand the dynamics of back EMF and the relationship of motor voltage and motor current being different than battery current....
Yep - and it's depressing how vocal some are in their ignorance. Not that I'm the least bit bitter, angry or frustrated... :D

I am very interested at what you find the amperage saturation point of the Warp 9 to be at. Would this be the most efficient point of operation, or would RPM/voltage be a larger factor?
I just posted this data around the same time as you posted, but saturation seems to occur around 400A, and it appears to be rather abrupt as major said, rather than a "gentle bend" as I predicted.

I'll defer to major on your second question, but I would *expect* for the RPM per volt ratio to go up quite a bit once in saturation because the ratio of flux per amp went down quite a bit.
 

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It appears that the WarP-9 goes into saturation (changes over from torque being proportional to the square of current to being linear) at 400A. The direct pressure readings from our hydraulic dyno:

200A 1014 rpm 24.7V <200 psi <- too low to read on gauge
250A 1010 rpm 28.7V 325 psi
300A 1010 rpm 31.6V 500 psi
350A 1015 rpm 34.4V 625 psi
400A 1008 rpm 37.6V 850 psi
450A 1015 rpm 39.0V 900 psi
I'll try this.


I guess I pasted it in here :) Ain't the smoothest sat curve I ever saw, but not bad. Looks like it just starts to saturate about 200A and continues to "knee" over thru 400A. Which one would expect with straight sided slots. Also, this isn't a true representation of the saturation characteristics because we have resistive voltage drops mixed into the voltage measurements. So we're not looking at the generated voltage alone. This is why saturation curves are most often taken at no load.

But interesting data Tess ;) Not sure what good it does anybody :)

major
 

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I am very interested at what you find the amperage saturation point of the Warp 9 to be at. Would this be the most efficient point of operation, or would RPM/voltage be a larger factor? I'm looking to operate at the most efficient point possible when I complete my conversion and am thinking that the Warp 9 might be too big for a highway cruising ~2500 pound car to get maximum efficiency but I could be wrong,
Hi MN,

I don't think you need to worry about saturation when considering motor efficiency in your context. Maybe if you were over exciting a SepEx or something like that. But "cruise" efficiency will best be maximized by choosing the proper ratio so the loading and RPM are "right" for the motor. And if the "cruise" power level is under the rated motor power, it means the motor 1) should not overheat and 2) should run efficiently.

Until you're very close to no load, if your RPM is reasonable, the larger motor should be more efficient than a smaller motor because the iron is stressed less and winding resistance is less. There may be a little more friction and windage with the larger motor, but the previously mentioned factors should offset that. Also the larger motor should run cooler, and cooler copper has less resistivity.

Regards,

major
 

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It shows that the Warp 9, and likely pretty much any series DC requires a very high battery voltage to get the RPM needed for 1000 amps of battery current to be matched.
IMO, it is the opposite. When you have a high voltage battery, your controller will likely always be reducing voltage to the motor and therefore motor current will always be higher than battery current (except when = 0). Take Tesser's last test there. If you extrapolate you would see a 1000A at maybe 45 to 50 volts. So if one had a 48V or lower V battery, the controller would go 100% dc at the 1000A CL whereas if you had a much higher voltage battery, it would not. Of course that was at 1000 RPM. So you could double the voltage at 2000 RPM and see 100% dc at CL or triple V (to 144) and see 100% dc at CL for 3000RPM. But if you have a 300V battery, 100% dc at CL would occur at or above 6000RPM, so your battery current would never equal motor current (except at 0 dc) because you're well beyond the zorch limit :)

Well, that's pretty confusing:confused: I hope you can follow it.

major
 
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Just a bit for all those who have decided to NEVER go back to see what's up with Jack.

Jack Rickard said...
My my my my my. Such a tremendous number of very strongly held opinions. Well, well, well, well....

I'm having a very happy end to a marvelous day thank you. And truly delighted to meet the EV Whisperer, Mr. Sebastien Bourgouis. We had a lovely day, and thanks to his very rapid analysis, we were drinking whiskey and partying lock Rock Stars by two in the afternoon.

Hate to give away this week's show, but I can't read any more of this battery amp/motor amp theory nonsense that of course never was and never could have been the issue. The motor loading issue was interesting, but as I noted, rather paints us into a corner of never getting well even with a nuclear power plant driving a 12000 lb motor.

Apparently, if the calibration of the hall effect sensor INSDIE the Soliton is off, it is quite possible for the Soliton to be entirely convinced it IS putting out 1000 amps, while the rest of the real world, including the fat kid, is kind of convinced it's more like 722. In that event, the device has a cunning strategy for self preservation, it simply limits itself to 1000 amps, even if they are not real.

If you replace that unit with a DIFFERENT Soliton1 from the magic bag, that does NOT have this calibration issue, guess what you get on the very first test drive?

A TOTALLY SMOKED Stage 2 clutch and pressure plate assembly. I mean NASTY SMELLING and pretty much destroyed.

Throught the mircacle of time lapse photography, we should have a new CB Performance kevlar double sided ceramic trick double throw me down stage 4 unit with 4000 lb pressure plate by AM tomorrow.

0-60 times to follow.

Quite a relief. And quite an impressive show on the first run.

Jack Rickard
March 31, 2011 11:10 PM


More is posted on the blog for you all to read.
 

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200A 1014 rpm 24.7V <200 psi <- too low to read on gauge
250A 1010 rpm 28.7V 325 psi
300A 1010 rpm 31.6V 500 psi
350A 1015 rpm 34.4V 625 psi
400A 1008 rpm 37.6V 850 psi
450A 1015 rpm 39.0V 900 psi

(HP = RPM x PSI x 0.0000182)
.
Does this mean that you are spending about 1kW per HP? Would that equate to a little over 60% conversion efficiency? I am interested in trying to gather similar data for another motor-controller combination to compare efficiencies.
 

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Does this mean that you are spending about 1kW per HP? Would that equate to a little over 60% conversion efficiency?
Hi jdd,

One HP = 746 watts. So Power out / Power in = 746 / 1000 = 74.6 %. Not too shabby for efficiency of controller, motor and pump at these loads, RPM and voltage.

I did not calculate the power out, just commenting on your 1kw/HP statement.

Regards,

major
 

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Hi jdd,

One HP = 746 watts. So Power out / Power in = 746 / 1000 = 74.6 %. Not too shabby for efficiency of controller, motor and pump at these loads, RPM and voltage.

I did not calculate the power out, just commenting on your 1kw/HP statement.

Regards,

major
thanks. I was calculating wrong.
 

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Discussion Starter #20
IMO, it is the opposite. When you have a high voltage battery, your controller will likely always be reducing voltage to the motor and therefore motor current will always be higher than battery current...
Loathe as I am to disagree with you, I think that it's worth pointing out that few battery packs appreciate having 1000A sucked out of them (much less the 2000A the Z2K could do), but most cars would benefit from having full torque beyond 3000 rpm, so I'd say it is definitely worthwhile to have more than 200V on tap even with an advanced motor like a WarP-9.

'Course, I am somewhat biased here... :rolleyes:


Just a bit for all those who have decided to NEVER go back to see what's up with Jack.....
While I obtained the data reported in this thread to support the argument that Jack Rickard had run out of voltage, I didn't start this thread as a rebuttal to Jack - it was strictly to share the data because I figured others would find it valuable.

It turns out Jack was right all along, but he never did tell me what the motor amps were. Seb had to fly up there to make that measurement in person, but then he was able to diagnose the likely culprit immediately.

We don't claim to be perfect, and we don't claim our products are perfect, but we are honorable people so when something goes wrong we try our damnedest to make things right.
 
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