[electrabishi]

Originally Posted by GerhardRP

Hey Mike, do you know what the gear ratios are on that truck?
Gerhard

Yes I do, let me get that for you...I need to find my Mitsubishi log book first (still packed up from the move from Alaska). Otherwise we can do a Google search for a Mitsubishi KM145 tranny ;-) I looked it up once but without my "book of knowledge" in front of me I'm at a loss. I'll be looking for it. My memory says the rear end is a 3.83:1. But I'll look for my notes.

Mike

[electrabishi]

Sorry, still haven't found my notebook (I have the Pinto notebook right here in front of me). Have moved ALL my stuff 4 times in less than a year :-( It will turn up and I'm zeroing in on it. Boxes.. upon boxes..

What specifically are you needing to find using the gear ratios?

Mike

[GerhardRP]

Originally Posted by electrabishi

Sorry, still haven't found my notebook (I have the Pinto notebook right here in front of me). Have moved ALL my stuff 4 times in less than a year :-( It will turn up and I'm zeroing in on it. Boxes.. upon boxes..

What specifically are you needing to find using the gear ratios?

Mike

Hi Mike,
Soon I will be ready to look at acceleration, so gear ratios and tire size will give the conversion from RPM to meters per second. I could use the speeds noted on the JPGs though.
As an update on the calculations, I have redone the resistance fits after accounting for the motor temperature. I also compressed the data set by averaging in 0.5 second intervals to reduce the noise. I now have resistance is 16.1 milliOhms and brush losss is 1.18 Volts. Subtracting these losses from the motor voltage I get the Back EMF. Dividing by rotational speed in SI units (radians per second), I get the field map as shown in the attached file.
I know you took data a week before the set you recently sent me... I would like to have the 1000 Amp data sets. Also, I would like some data in the low current region to fill things in if you have any.
Yours,
Gerhard

[electrabishi]

Yes when I was plotting these out with Excel I was doing a moving average on 1 samples (so 1 second averages) to smooth it out. But that was just for visual display purposes.

Keep in mind the temp reported is not motor temp, its the controller heat sink temp. The trend may track in the same direction but I do not have any accurate temp data on the motors, for th Mitsubishi.

I'll pull up that previous weeks data you mentioned. I have lots of data sets, many of which I have never even opened up to view Will mail them to you directly.

Mike

[GerhardRP]

Originally Posted by electrabishi

I have lots of data sets, many of which I have never even opened up to view Will mail them to you directly.

Mike

Great...
Did you ever do a coast-down? Start with 60MPH then no throttle down to say 20 MPH to get drag and Rolling Resistance?
Gerhard

[electrabishi]

Nope never did a coast down. The controller right now is in Alaska racing in a Junior Dragster so as soon as it comes back I can do that test.

Here is the tranny and rear end gearing:

Mitsubishi KM145-8 Manual 4WD Transmission
Gear ratios:
First ………………….…………………. 3.967 : 1
Second …………….……………………. 2.136 : 1
Third …………….……………………….1.360 : 1
Fourth ………….………………………... 1.000: 1
Fifth ………….…………………………. 0.856 : 1
Reverse …….…………………………… 3.578 : 1

Rear Differential .................................... 3.909:1

Tires 225-75R15

Mike

[GerhardRP]

Originally Posted by electrabishi

Nope never did a coast down. The controller right now is in Alaska racing in a Junior Dragster so as soon as it comes back I can do that test.

Mike

Actuall the typical drive dataset includes a couple of coasting segments. Question is are they on level ground?
The BEMF/Speed from this data set is attached.
Gerhard

[Tesseract]

Originally Posted by GerhardRP

As an update on the calculations, I have redone the resistance fits after accounting for the motor temperature. I also compressed the data set by averaging in 0.5 second intervals to reduce the noise. I now have resistance is 16.1 milliOhms and brush losss is 1.18 Volts.

We get similar results... the following is the scatter plot of calculated resistance for a Warp 9... not corrected for temperature. The skewing/spreading of the data points at low currents is mainly an artifact of the very low duty cycle.

[GerhardRP]

Originally Posted by electrabishi

Nope never did a coast down. The controller right now is in Alaska racing in a Junior Dragster so as soon as it comes back I can do that test.

Here is the tranny and rear end gearing:

Mitsubishi KM145-8 Manual 4WD Transmission
Gear ratios:
First ………………….…………………. 3.967 : 1
Second …………….……………………. 2.136 : 1
Third …………….……………………….1.360 : 1
Fourth ………….………………………... 1.000: 1
Fifth ………….…………………………. 0.856 : 1
Reverse …….…………………………… 3.578 : 1

Rear Differential .................................... 3.909:1

Tires 225-75R15

Mike

Hey Mike,
What was your commuting distance for the "typical" data set you sent?
Integrating the speed using these gear ratios and finding your shift points, I get 7.93 miles.
Do you have a dataset with 85 MPH on level ground?
Gerhard

[The Toecutter]

Gerhard, thanks for posting that data! What unit is omega supposed to be expressed in within that pdf? Normally, it is 2pi/T, but I'm not sure if that is what you mean with that symbol.

At 5500 rpm, you get 576.66 for omega when expressed in radians per second. At ~0.32 BMEF per omega at 600A, then the torque generated at 600A should be produced at 5500 rpm at 184V. But, 184V and 600A into the motor is 110.4 Kw electrical, and given that at 600A the motor will produce about 120 lb-ft, at 5500 rpm, this is ~94 kW mechanical, giving an efficiency of 85%.

Provided this is correct, that's not too bad! But it seems quite optimistic for power to be made that high in the RPM range, given the dyno results for cars like Otmar's 914 and his 8" motors, and it would also seem optimistic for efficiency to be that high with that amount of current given the amount of losses from heat alone at that current, let alone losses from the high rotational speed of the motor, brush losses, ect.