Smart Pie controller programmer

[Kris]

Hi guys,

I'm playing around with the Smart Pie programming software for PC. Interesting but equally mysterious.

Here's a picture of the interface (for some reason my prt scr functionality is dead):

http://i.imgur.com/x0Waf.jpg

Have a few questions:

1. Why is a 48v motor / controller set to 24v? (I'm running a 48v 10ah lithium battery pack).

2. Any thoughts on what "Break time" might entail? I thought it could be the amount of time it takes for regen to go from activated to fully stopped, but tests don't support that.

Appreciate any thoughts / comments!

[Bikemad]

Hi Kris,

I'm curious as to where you downloaded your software from as it is very different to the current software on the GM site:





Which I discovered has a maximum regen setting of 116%.

I have now seen at least five different versions of the PD-280 software, but this one appears to be somewhat different to the others.

I'm guessing it could be for a wheelchair controller, as it does not support any of the pedelec (PAS) functions, or allow reverse to be disabled either.
In which case, the "Break Time" function probably should be "Brake Time", and may adjust how long the controller waits for the electro-mechanical brake to fully disengage before the motor is allowed to respond to the throttle input. This would prevent unnecessary load on the motor by trying to turn the wheel while the parking bake was still partially engaged.

As far as I can tell, the "Motor Voltage" setting is there to set the Low Voltage Cut-off point of the controller to prevent the battery from becoming overdischarged.
Most modern batteries (apart from DIY LiPo packs) seem to have their own Battery Management System built in, so this setting is not usually necessary.

If the controller was factory set to 48V, users with 24V or 36V packs would not be able to use their motors without reprogramming them, and the USB leads are not always purchased with the wheel kits.

By having a factory default setting at 24V, users can simply plug in a 24V, 36V or 48V battery and use the motor straight out of the box without any need to change program settings.

I have all my controllers set to 24V to allow any of my battery packs to work with all of my motors, without having to reprogram the controller every time I swap batteries.

I suggest you try downloading the latest software on the GM site and see if it can be used to adjust your regen to a usable level for your micro scooter.

Alan
 
P.S. Check out this link for more information on the Print Screen function.

[Kris]

Thanks BikeMad you're a treasure. We got the software emailed to us by the GM salesperson we bought the battery pack from. Will try the new software, the wheelchair version claimed to be saving files but no matter what we did adjustment wise, it made no difference to the scooters performance.
I'm keen to see what happens with the motor set to 48v. The machine already scoots up 20 degree slopes like a rocket (our guestimate for max slope based on the 48v motor specs was 14 degrees).

[Kris]

Scooter MkII with the home brew 48v 10Ah battery pack, 39 x NCR18650Bs (6s3p hidden in the scooter frame tube & 7s3p in the little battery box). I bought an off-the-shelf BMS to run this lot but having 2nd thoughts about it because the Panasonics are all holding within a few millivolts of each other & a couple of commercial battery push bike type packs I've dismantled are BMS less.

[GM Canada]

Interesting project, how on earth did you get the cells in the frame?

Gary

[Kris]

A bit fiddly but got there in the end.

[GM Canada]

Very cool! It must be tricky to get everything soldered together so it will last.

Gary

[Kris]

Time will tell I guess, joining 3 solder tabs in a robust fashion certainly a head scratcher.

[Zerogee]

Hi kris,

I have looked at a similar application to yours with the SmartPie for myself but have been unsure if my max speed calculations are correct. Based on some data /info I have found online my estimates are between 18-21kph. However, I am not sure if I would be happy with those estimates. Could you tell me what max speed are you getting with your setup?

You say...

The machine already scoots up 20 degree slopes like a rocket

Does this mean you are seeing minimal reduction in your speed on those climbs?

Also, I am trying to figure out if I need to add the disk brake for my setup. Do you use the regen braking to stop? Is that enough on it's own?

Thanks for the info.

Myron

[Kris]

Top speed 22kph Myron, however it does drop with slope angle. It depends a lot on the battery pack, the commercial 48v 10Ah packs hold up better under high discharge than the pack I made up from Panasonic NCR18650s. Regen is savage at low speed but curiously gets gentler at higher speeds. The config software is dysfunctional, motor voltage is supposed to adjust low voltage cutout thresholds but, like the regen controls, appears to do nothing at all.

[Yoma]

Hey Kris,

I take it that must be MW-12SP -- 12" Motor Wheel you've got on there ..

And if so whats resistance like if you need , or wanted to use it without the motor i.e. manually ? ( I heard smartpie on bike hubs freewheeled better than the old MPs )

Im guessing though that might just be the size , as I see no difference between 12SP or 12B in weight ..

yoma

[vpersiani]

Regen is savage at low speed but curiously gets gentler at higher speeds.

If I understand correctly the way it works, regen will generate strong force at each phase of the motor which in the MP3 case means 3 times per motor / wheel revolution. This is why at low speed you probably feel those 3 hard points per rotation while at higher speed this feels much smoother.

My $0.02 (or is RMB2 )

Vincent

[Bikemad]

Vincent,
I think you must be envisaging a three pole brushed motor like this:



But even this motor would have six switched pulses per revolution, not three.

The Smart Pie is a 40 pole three phase brushless motor, which means there are 120 switched pulses per wheel revolution during regen!

Each switching operation is dependant upon the output state of each or the three hall sensors, which effectively transpose the electrical polarity at the end of each corresponding phase wire in sequence.

Just consider for one moment, all those poor tiny little electrons, all running as fast as they can in the same direction inside the wire, suddenly having to simultaneously do an emergency stop, a quick "U" turn, and then sprint off at full speed in the opposite direction.
At 300rpm, all of this is happening more than 200 times every second on each of the three phase wires. So it must be absolutely chaotic inside the phase windings at high rpm.

If this is not the reason, then I suspect there must be another (more plausible) explanation for the reduction in the regen braking force at higher speeds.

Alan
 

[Kris]

12" SP is hard work when the battery goes flat. Even if you switch the battery pack off the motor still regens into the internal motor controller & those useless throttles with the random display lights (how hard can it be to design a 3 led battey indicator that actually works?) which means you get a good physical work out if you try to scoot along manually, easier enough to walk it though. I've got a hunch a lot of regen issues on the SP are down to software rather than physics. My unit will skid the SP wheel below 10kph if I engage regen yet above 18kph it's quite usable down hill. Sometimes with the throttle off regen just comes on when it's not selected. Many a time I've watched negative currents on the cycle analyst just ramp up over a few minutes down hill only to vanish as the speed picks up. I'm in the process of wiring a Kelly controller up to a 12" SP  just t see what on-the-fly variable regen is like.