MP3 Braking hardly working

[Electric dreams]

Hi fellow ebikers.

I don't think this is a repeat of "MP III, no brake effect from the motor" Post.

I have recently purchased a MP III with 36V. I set up everything and connected to USB before powering up. It was set to 24v with 50% regen. I set it to 36v and left the regen settings. I didn't change anything else. I haven't connected the PAS.

Now, if I use the thumb throttle then try and brake, nothing happens with the regen on both brakes. What does work is that the throttle becomes disabled when I press either brake, so the signalling is working on both brakes but no regen.

I tried changing the regen to 80%, but no joy. I know the USB is working as I set it to reverse and it went backwards.

Another strange thing - When I have the throttle pressed down, then press the cruse control ( with throttle still down ) and then let go of the cruse and throttle, it just cuts out, no cruse. So, it seems that there is something wrong with the cruse. I checked the wiring inside the cruse and it looks good.

I have visually checked all the cabling and it looks good, no bent pin etc. Maybe I need to play around with the regen on USB to wake it up.

Anyway, any help and advise would be appreciated.

Al

[Leslie]

Does the motor start smoothly every time when there is a load placed on it?

Also on some controllers the battery voltage needs to be set correctly.  Wasnt the case with previous Pie's though.

Regen doesnt work if your hall sensors have failed and the controller switches into sensorless mode, this is sorta obvious, because the motor isnt very smooth in all take off operations on sensorless mode. But no cruise control is another sign something else might be a miss.

[Electric dreams]

Hi Les,

The motors starts perfectly and no judder under load. I took it for a short ride and it goes really well, it just doesn't stop!.. The battery was set at 24v but I changed it to 36v.

I am going to check the wiring using a multimeter, but the fact that the cruise control doesn't work makes me think there is a bigger issue as you noted.

If anyone has any ideas how to prove/disprove what is/isn't working, that could be great. Maybe there a post relating expected voltage settings etc under certain circumstances.

Thanks
Al

[Electric dreams]

Just to update.

I checked the controller cable with multimeter and all is good.
I set regen to 116% ( max ) and it does slow it down slightly but hardly worth it
I did a couple of mythbuster type tests and it makes a marginal difference.
What settings should I have for max braking?
Still nothing when I use cruise. Used correct technique but no joy
Still looking for a solution.

Thanks
Al

[Leslie]

From a feel point of view, A rule of thumb I go by is not to slow the bike down too much faster than you can accelerate. One can take 15 seconds to get up to regen speed, but take a split second to slow down.  Thats gotta be bad for the batteries.  Additionally we only need to assist braking.  I don't really see Regen for my uses much good for anything other than enhanced braking.  Regen is an awesome way to save your brake pads and increase stopping power considerably, especially in wet conditions.

Not sure about the MP3's, but some controller have an EBS, that allows regen current to back right off with decreased RMP, to off, if the wheel locks up. And your wheel wont lock if you adjust off your hubs mechanical brakes. So there is a hint too.

Ideally you don't want your bike to stop on average medium grade hills using regen alone. It also depends on your weight. It becomes a personal thing, for each bike, rider, and motor.  Some larger framed people are better suited to more robust type battery cells, and require a reliable regen to take the load off the brakes at higher speeds.  A good strong fet bridge would help for heavier configs too.

Id test the current draw between ground and the Cruise Control signal wire with an amp meter set on milliamps.  The test the continuity of the switch with the meter too.
 

Hold the accelerator at a certain spot still for 5~10 seconds and see if the it triggers an auto cruise control.

[Leslie]

BTW whats your wheel size and your max speed?

[Electric dreams]

Thanks Les for your advise, you are correct, it takes some time and speed to build up before the regen brakes are effective. I was just going up and down the 20meter drive and nothing was working on brakes or cruise, so I took it for a proper spin and they both work fine.

I have set the regen to 50 percent and it is ample.

I really appreciate the feedback these forums give you as there are no proper instructions.

Finally I can start whizzing to work!!

Haven't checked the speed yet, but its fast. I am running on 700x32c
Thanks again Les

Al

[Leslie]

I believe the larger rims don't give up as much regen as the smaller ones that run at higher RPM.  Also with higher volt batteries, the peak RPM of the motor suffers vs the motors ability to deliver good current.  This is why we have this setting, to tune the regen for optimum performance on a wider ranger of systems. 

The motor will not by itself spin up fast enough to deliver a high enough voltage to recharge a battery.  The controller introduces a little reverse switching to trigger a back emf large enough for the generator function of the motor to induct a large enough voltage potential get over the battery voltage.  The larger rims hubs require a little more help in this department.

[Leslie]

Oh and switching up your phase currents on a rim like that may improve your top speed and initial take off torque a little, be gentle on the 6 fet bridge though.  More phase current may improve the regen  too.  Not sure about that one though!

[Leslie]

The good thing about the internal controllers, it give you something out of the box that works.  When you start playing with that program cable and wanting more power, things might go south, if you what I mean.  I've had these controlers last for a year, and some for a week .  Too much regen on that 6 fet bridge will be its death.  I always push the little things till they die to see what they are capable of.   I have special needs so I jump to the next size up pretty fast. 

Im getting an MP III 20", for the young lad who had his BMX stolen, this should go well for a while while with the internal controller.  The small rims don't require such a large controller to make them jump off the mark, so low on the phase current and continuous current.  This weight controller should work good on the 20" rim.  I believe the MP III supports higher voltages, well I estimate on the 20", the MP III controller should perform forever if set conservatively. With the higher volts, you can set the speed back to more legal speeds in the programing.

I do want to experiment with the large rim like you are. a whole different kettle of fish.  Have fun man.