Compare Pedal-First and Self-Start Controllers?

[The7]

Use the same voltage and ampere Pedal-First and Self-Start Controllers for the same motor.

After starting up, which controller will have a higher max speed and higher torque? Why?

It will be great if you have personal experience on both type.

 

[Ypedal]

I have both, and i prefer the Instant Start.

Top speed, and torque at X voltage are very similar ( DB may show a difference, but no big seat of the pants difference ) both were tested back to back at 36 and 48v, 20amp controllers.

The pedal first trips my LiMn pack's BMS for some strange reason.

I like using motor power along with the legs for jack-rabbit starts, the pedal first sucks when taking off on a hill specially when you forget to shift down after a long strech of high-speed running and find yourself at a green light in a tall gear.

The pedal first would be useful in 2 ways

1- If you rip out your Hall wires by accident and want a quick fix

2- safety, the bike will not GO from a dead stop, with kids, or if the bike has to be left unsupervised with a battery pack mounted to the frame..

 

[The7]

I have both, and i prefer the Instant Start.

Top speed, and torque at X voltage are very similar ( DB may show a difference, but no big seat of the pants difference ) both were tested back to back at 36 and 48v, 20amp controllers.
.

Thanks for the information which I would think so.

The pedal first trips my LiMn pack's BMS for some strange reason.

Have you found out WHY?
It seems that the BMS sensed something wrong about the pedal-first controller or it is very sensitive to short-time "over-current" due to some unseen problems in the PF controller.

From the output voltage waveform, there are a lot of PWM switching which will have a lot of "erratic zero-crossings". Most PF controllers use the zero-crossing of the back emf for the commutation.
However the zero-crossing of the back emf is contaminated by the "erratic zero-crossings' of the PWM, and the PF controller may commutate at the "wrong" time and could cause a short-time "huge" current. This short-time "huge" current could trip the sensitive BMS.
This short-time "huge" current may not be shown up in your digital ammeter because the displayed value is the "average value'' over a period.
Some papers show that some advanced filtering technique (say Kalman Filtering) could be used to filter out these "erratic zero-crossing". Most PF only use simple filters.

PF controllers cannot be used for hub motors with internal free-wheeling (unless the motors are being started by some electrical means in the design).

 

[Ypedal]

http://endless-sphere.com/forums/viewtopic.php?t=1537&start=0

This is the thread i had going about the PF controller and my BMS problem, i was not able to correct the problem other than simply switching back to an IS controller. :?

I'm not an EE, so most of the post above went WOOOSH.. straight over my head :lol: , tho i do grasp the concept of what you describe, thank you !!

I asked Andy at FalconEV about the BMS trip, he suspects overcurrent ( 35 amps on this BMS ), so that goes with your description of the problem..

Solution : Change controller .. doh.

This controller has Justin's DB shunt built-in, i did not try limiting the amps to 20 thru the DB, i wonder if it would correct the problem by providing filtering ???

 

[The7]

Ypedal,

In the other post, you said:
"I finally put my Giant ATX back together, it now has a front wheel Crystalyte 407, and i installed a " Pedal-First ' controller at 36v 20 amp.

The phase wires had to be swapped in order for the motor to rotate the proper direction with the Pedal First so it's

Blue/Yellow
Green/Green
Yellow/Blue

The same motor on an Instant Start controller uses the same color to each other."

It is very in-consistant in design that it needs to swap the phase wires between the controller and motor from the same make.
Did you find it out experimently or do according to installation instruction?


Yours is a PF controller with three 3 big 100V 100uF cap which are absent in my old version of IS controller. I think the new version IS will also have these big caps.

I am doing some experiments and try to add external modification to the IS controller in order it could work as an sensorless PF.

 

[Ypedal]

It was quite accidental, i spun the wheel by hand off the ground before i applied throttle, and knew right away that it was not going to be ok

The motor felt exactly like when you push your bike backwards.. alot of magnetic resistance, i swapped Yellow and Blue for trial and error and it was the right combo on the first attempt, draws 0.7 amps at no load if i recall correctly.