low acceleration Smart Pie 4

[Dan77062]

I am setting up two new Smart Pie 4 vector motors and find that the acceleration is very low compared to posted videos.  Both motors perform the same.  Also, the acceleration setting (20, 40, 60, 80, 100) makes no discernible difference.  It is a 12" hub, mounted in a frame, not yet pulling a load and it takes about 6 to 7 seconds to get up to speed.  Decel from full speed to zero takes about 2 seconds.

It is not a battery issue, as I am using a power supply that can deliver 50 amps and the draw is only about 1.2 amps at 240 RPM, which makes sense since it is basically no load.
The input voltage changes the top speed, but has no effect on the acceleration.  I used 24, 36, and 48 volts to test.

The initial startup is not completely smooth.  There is a bit of stutter and clunk, but it is quiet, hardly noticeable, and is only present for the first second or so.  At full speed the motor runs very smoothly and quietly.

The motor spins freely in both directions with no power applied, so it does not seem to be a friction issue.

Here are the parameters:
Regen braking enable: 1:Enabled
Reverse enable: 1: Enable
PAS ratio 30
Nom batt V 24
Overvoltage protection 59
Undervoltage value 19
Battery drawn current 25
Rated phase current 70
Max forward speed rpm 240
Decel level 1 (rpm/s) 120
Max EBS phas current (A) 80
Acceleration 100

Thoughts and suggestions appreciated.

[Bikemad]

Hi Dan,

I think you have been using the early vector software on later vector controllers which would cause the slow acceleration that you are experiencing.

When the acceleration is set at 100% it should be almost instant, but if you use the wrong software and reprogram the controller the acceleration setting will not go above 5% (even if 100% has been entered and accepted) because you cannot increase the acceleration setting above 5% using old vector software on a newer vector controller.

The original vector controllers and software only allowed 5 different values of 1, 2, 3, 4 or 5 to be stored as the acceleration parameter and these equate to 20%, 40%, 60%, 80% and 100%.
The later controllers and revised software allows 101 values of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. right up to 100 (or presumably the hexadecimal equivalent) to be stored as the acceleration parameter and these directly equate to 0 - 100%.
If you use the old software, it stores 100% as a value of 5, but the later controllers will interpret a value of 5 to be 5% not 100%

Try downloading the latest software on the GM website and see if it makes a difference.

If you are unable to unpack the "PI-800.rar" file you might want to try the "Revised GM_v3_1_1(201406231)_GED.exe" file instead which can be found here.

Alan
 

[Dan77062]

Hi Alan,
Solved!  Thanks a million.  I thought I had the latest version of the software, since it is named "LBMC_GUI_v3.1.2_GoldenMotor.exe" which sounds like a later version than "Revised GM_v3_1_1(201406231)_GED.exe"  However, you were absolutely correct-- when I opened the version you suggested, it showed that my acceleration setting was 1.  Change that to 100 and the SmartPie goes right up to speed.  Thanks!

Since you are on a roll, perhaps you can help with another question:

I do not need much speed, this is for a robot not a bike so the top speed will be around 120 RPM.  I was planning to use 24V batteries but I find that the SmartPie does not consistently start up if the voltage is below around 25V.  I have the battery voltage parameter set to 24V and the low voltage cutoff at 19V.  If I set the power supply voltage to anything below 22V, the motor will only start around once every three or four tries, turning the throttle and letting it go back to 0.  At 24V it starts about 80% of the time and above 26V it starts every time.  If I give the wheel a push, it starts almost every time even at the lower voltages.  Is this normal?   Does it mean that a 24V lead acid battery will be inadequate to power the motor when it gets partly drained?  Since lipos hold voltage longer into their discharge cycle, perhaps they are a better choice.  Do you think I can use 6S lipos (22.1 nominal voltage, charges to about 25V) to power the motors.  Do I need to move to 8S?

Oh, one other thing.  I noticed that when the software is not connected to the controller it shows many more parameters than when it is connected.  Is that normal?  Screenshots attached.  The one showing the not connected state has many additional parameters off screen.   Any thoughts on the parameter settings in the attached screenshot are appreciated!

Thanks again for the help!

[Bikemad]

It's good to know that the acceleration problem was due to the wrong programming software being used.

I haven't tried running my Smart Pie on lead acid batteries so I don't know if it is normal to experience starting problems when running it on 24V.
I normally use a lightweight 8S LiPo pack, although sometimes I do occasionally use a 14S Lipo Pack instead.
I haven't actually tried a 6S pack, but I seem to recall it worked OK when I briefly tested it on a 7S pack.

Are you using the GM throttle supplied with the kit?

Regarding the parameters, the same programming software is used for programming several different controllers, but only the parameters that are applicable to each specific controller is available during programming.

Alan
 

[Dan77062]

Sounds like the 8S lipo is the way to go.  Do you have a suggested source for 8S Lipos?

I used the included GM throttle for testing, but am actually running the motors with an analog voltage generated from an arduino coupled to a digital to analog converter.  The range goes from about 0.9 to 3.5V.

See this post regarding the modification I made to the controller to get a hall sensor signal out and use it as an encoder signal for the robot chassis:
http://goldenmotor.com/SMF/index.php?topic=5389.msg30984#msg30984

[Bikemad]

Sounds like the 8S lipo is the way to go.  Do you have a suggested source for 8S Lipos?

I use two of these cheap and powerful Turnigy 5000mAh 4S1P Hardcase packs from Hobbyking.com connected in series:



I use a standard 40 Amp fuse with the Smart Pie:



But I made a special 80 Amp fuse for my modified Magic Pie as the fuse holder just couldn't cope with the high current:

 

Alan
 

[Dan77062]

Outstanding answer, very much appreciate the photos, ordered a bunch of those batteries just now.

Perhaps we can continue! 

I am using the reverse feature by applying ground to the blue harness wire and that is working OK.  However, the reverse speed is different from the forward speed.  With the same voltage input to the throttle (or with the actual throttle turned to some specific point), the forward direction goes at about twice the speed of the reverse direction.  It looks like there was control over this in previous versions of the software, but in this version there is only enable/disable for reverse.

I tried three different versions of the software, 3.1.1, 3.1.2, and 3.2.0 as follows:

   From your dropbox folder:
LBMC_GUI_v3.1.2_GoldenMotor.exe
and
Revised GM_v3_1_1(201406231)_GED.exe

and also from the golden motor site:
unpack Pi-800.rar to
PI-800.exe which opens with a title line of
LMBC GUI V3.2.0(b14-1112)

I noted from another thread that there is a version
LBMC GUI V3.1.3(b14-0704)
but have not been able to find that one.


None of the three I tried show the "Maximum Reverse Speed" parameter that I see on other posts.  The GUI looks the same for all three (image posted above), but as you pointed out, the 3_1_1 revised provides for full acceleration.


Insights?

[Bikemad]

Dan, the LBMC GUI V3.1.3(b14-0704) comes from Gary's website (goldenmotor.ca) but this version still does not have any setting for the reverse speed either.

I will make some enquiries and see what I can find out.

Alan
 

[Bikemad]

I have just been looking at your settings that you posted previously:

Max forward speed rpm 240
Decel level 1 (rpm/s) 120

Try setting the "Decel level 1 (rpm/s)" to 240 and see if it makes a difference, as I have a feeling that it may be a translation problem during the writing of the program and I think it should read "Max Reverse Speed (rpm)" instead.



Alan
 

[Dan77062]

OK, you are officially amazing.  Worked perfectly.  Never would have occurred to me to think of a translation issue to mess up a line that way, especially the rpm/s to rpm, not even the same units.

I can't even count the number of hours and amount of frustration you have saved me.  Let me know if there is ever anything I can do to help you in return.