Can a controller be to big? (Modified Bionx motor)

jocoman

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Sep 3, 2010
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Hi Folks. I hope someone can sort me out.
I took a 350w Bionx motor and removed the internal controller. It is now just a plain direct drive motor 3 stator wires and the 3 hall leads plus power and ground.
I ordered a KT controller from aliexpress. Thinking bigger is better I ordered the 50a model. I have tried all combinations of the hall sense wires and stator wires and I get the wheel to go either superfast/high amps, super slow low amps, or clunky. No sweet spot.
I mentioned this to the aliexpress store and he said the controller I bought was for a 2000 watt motor and that I needed a 17 amp controller.
So, can this 50 amp controller be made to work , or do I purchase the 17amp controller and see if that works?
Here is the link to the controllers
 
Have you tried to adjust C5 to limit the controller current?

If you set it to 3 then it will limit it to 25 Amps maximum.

Also you don’t want the controller set to a higher current than you battery can deliver otherwise you will ruin your battery.

And you have to be careful that you don’t overheat your motor or the insulation on the windings could melt and you could cook your magnets.

Another thing to consider are your phase cables and connector need to be big enough to take the phase current otherwise they can melt also.

The motor will try to run at whatever the controller feeds it and you are currently trying to run it at 50 amps, which is way too high for a little Bionx motor.

You may be able to get away with it if you reduce the controller current to 25 amps. And make a few other adjustments to the P and C settings.
 
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A bigger controller will heat up the motor quicker; but it will still work. You need to find the right phase/hall combo; regardless of the current rating of the controllerHRaeRi4.jpg.
 
That's the problem. I have tried all the combinations (36 in total) (several times) I either get super fast, or super slow or it just clunks or sometimes a clunck with a bit of rotation.
I changed C5 to 3 but it did not seem to have any effect.
What would be a more suitable controller. I have the display so I Guess a KT type would be better. Would this work?

 
Have you ridden the bike with C3 set to 03, or just tested it unloaded?

You should go back to one of the 3 phase combinations that make it go super fast. That will be the correct combination.

If you test ride it you should get a maximum speed of around 30 mph, but be careful you don’t overheat your motor because it will be running at over 1000 watts with full throttle.

Also do you know how much current your battery can safely deliver? That will determine what maximum current you should set your controller at.
 
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The motor is not laced to a wheel at the moment. I am bench testing things, so it is unloaded. I would say the battery can peak at 20 but run at 15 amps.
When in super fast mode it draws 22 amps.
 
Update: At the super fast setting, the motor only runs for about 3-4 seconds and then stops. This may be the correct setting, but it will only run for 3-4 seconds.
 
Are you doing these tests at full throttle and if so, is your battery sagging and hitting the low voltage cut off?

And what is the watts reading on the display when the motor is running?
 
I don't think the battery is sagging. BTW where should i be measuring current? at the battery or at one of the stator wires?
txs
 
Here is something else that is interesting;
In the diagram above, the start diagram produces a a smooth rotation but does not go very fast and it is in the wrong direction.
I changed the wires in the hall and phase as indicated on the diagram expecting it to change the direction of rotation, but instead it went to that super fast mode that then cuts out. Strange. Could I have somehow screwed up internal connections? It I wonder why it did not reverse direction. maybe that's a clue to what's going on....
 
Some of the combinations result in a reverse rotation on a direct drive motor.

If you have a clamp meter then it’s best to measure battery current. Then you can keep an eye on things during testing so you don’t overload your battery.

I prefer to use the table that I have attached rather than the one posted above. It’s easy to print off and to write in the results as you go.

If you don’t have a clamp meter you can substitute amps for watts in the table. With the correct combination the motor should spin smoothly in the correct direction at less than 150 watts unloaded and should not cut out.

And also even though the table says there are 3 correct combinations, but only one runs best, that’s not correct. Any one of the three works fine.

2DFE7521-DA52-4282-B28F-0DB7574B7B24.jpeg
 
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Did you glue the hall sensors in place after removing the controller board?

If they aren’t fixed in position properly then maybe they are moving around, causing the motor to cut out.
 
Thanks. I'm close to giving up.
see this thread

I think its an issue with KT type controllers and my direct drive hub. The hall sensors were quite solid in they way they were mounted so I didn't add any extra epoxy.. But centrifugal force maybe doing something for sure.

So I either buy a new hub motor to match this KT controller or buy a new non KT style controller with learning function to match the hub.
kinda screwed because I have all the compatible KT style LCD monitor and throttle stuff.

Which way should i go?
 
Swapping al of the phase and hall wires is just a manual way to do the learning.

It’s very tedious, but it should work, because now you have removed the electronics from the Bionx motor it’s just like any other sensored direct drive motor.

You have had it spinning fast in the correct direction, albeit only for 3 to 4 seconds so it does run. You just need to find out why it cuts out after such a short period of time.

Did you refer to the Grin video when you modified your motor?

 
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Another thing you can try is to cycle C2 from 1 to 7 to see if changing the phase angle makes the motor run continuously. Assuming it’s currently set at default 0.
 
Swapping al of the phase and hall wires is just a manual way to do the learning.

It’s very tedious, but it should work, because now you have removed the electronics from the Bionx motor it’s just like any other sensored direct drive motor.

You have had it spinning fast in the correct direction, albeit only for 3 to 4 seconds so it does run. You just need to find out why it cuts out after such a short period of time.

Did you refer to the Grin video when you modified your motor?

Yes. the Grin video is what inspired me. i just didn't want to buy a $500 controller.
 
Unfortunately C2 can only toggle between 0 and 1. No other settings. Doesn't seem to make any difference if set to 1 or 0.
Txs
 
Does the motor run continuously on PAS or low throttle or does it still cut out?
 
Ok. progress...maybe
I have it running without stopping. I think it had a poor field connection.
It is kinda of noisy and draws 12 amps if C5 is set to 3 and 14 amps if C5 is set top 10.
so what's my next move ? run thru the combos again?
Txs
 
Yeah that’s one of the rough running combinations. Battery current should be less than 3 amps at full throttle unloaded with the correct combination.
 
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