9C - infineon controller playing up

[Kurt]

I will try and give as much detail as I have a strange issue that has me really stumped.

I am running a little 12 fet 48v 45a 9c controller- apparently its identical to the 12 fet infineon. Its powering a turnigy 80/100 with halls installed. Now on 36 volts everything is fine. Very snappy throttle control over the full rpm range. No stuttering all good all works perfect. On 36v you can see a good 38 to 40a on acceleration from a dead stop or when you come to very big hills. It all works as expected.

Now my problem starts when I try and run 15s lipo or around 60v hot off the charger. The motor seems to be sluggish at low speeds- low rpm. Its like its limiting the amps to around 10 - 15 amps until the motor reaches around 70% of its WOT rpm then it takes off and can draw 40amps.

Today I was towing my daughter in a child trailer at 60v. So this loaded weight configuration should easily show 1500-2500w 30 - 40amps under hard acceleration. I was struggling to see more than 800w..10-15amps on the CA under acceleration. Then when I let is slowly climb in speed to say say 38kmh about 70% WOT rpm It would slowly allow its self to draw more amps 30-40ish. Back to 60v and the same thing again.

I did a test experiment and switched my lipo pack back to 10s 36v and I had my acceleration instantly back again. At 36v it would draw a good 1500w had enough punch to slip the clutch and back wheel a little.

Why would the controller act like this at 60 ?

Its strange because it did this on the weekend at 60v but now it seams to be getting a lot worse today. On the weekend I could get a good 2400w on the CA and a good 40ish mph top end it had some punchy mid range acceleration but still a little strange and soft down low. There is something funky going on at 60v.

Its got me stumped.

Edit: Another issue I can think of that comes up at 60v is when you set the cruise control at say 15km... 20% throttle and let go of the throttle. It will stay at the set 20% throttle then every 10 sec or so it will give a little burst of power like its struggling to stay locked on. It doesn't do this on 36v.

Kurt

 

[Kurt]

I am going to head out today with a video camera and CA watt meter. Hopefully show what's happening at 36v and at 60v. It might make it easer to see what going on.

Will post video soon.

Kurt

 

[Kurt]

Ok this video was taken when I first ran it on 15s lipo. its a little sluggish just of the line but has plenty of mid range punch and good throttle response. It would pull a good 2000W- 2500W with good punch up the hills.Although I was getting a slight whiff of the issue at this stage but wasn't anywhere close to as bad.
[youtube]ehN5pbE16o4[/youtube]

This was taken today towing a child trailer to load the system up just to exaggerate the problem. This video is on flat ground rolling along at 5kmh then just giving it WOT and letting it do its thing. You can see how it struggles to pick up speed and is very conservative on the amps-watts only pulling about 1000w . If you give it enough road to pick up speed eventually as it reaches around 70% of max speed it will allow its self to draw higher amps 30 - 40amps and you do then see the 2400w.I was thinking even a bad connection or plug but then why can it draw high amps when the motor is at speed? If it was a high resistance connection it would limit current all the time.

its like there is relation that the more load you place the motor under the less amps its letting it draw :? Its the opposite to what I would expect. Take a hub motor and give it WOT while dragging the brake and you will see the amps shoot up as expected. I did the same test at 20kmh and loading it up by dragging the two front brake and my amps went down as the motor was loaded. The lipo has the balls and isn't sagging. So its like the controller is saying NOOO! and backing the amps off?

I thought I would add that the CA is a stand alone unit and is not limiting amps or speed in anyway its totally independent of the controller.

[youtube]6hbyvhbtv28[/youtube]

What's go on were is my amp hungry snappy fast performance. Is the controller coming to slow death and why only letting the motor draw decant current once at speed? Usually the amps drop off once at speed its got me stumped.

Now this video is at 36v you see it has no issue feeding a good 38-40amps when I gave it WOT from a stand still and then up a hill. Just Ignore the voltage sag in this vid it was done with 36v of lifepo4.
[youtube]zGFfXdzHHAw[/youtube]

As you can see under the same conditions as the 60v test but at 36v it can easily pull 40amps and jumps to 1300w in a few seconds of WOT at 36v.Compare that to the 60v test it struggles to pull 10 to 20 amps and slow acceleration as it takes many seconds to slowly draw 500- 800- 1000w. It should just jump to 2000 - 2400w within seconds. :?

Kurt

 

[Kurt]

Any ideas?

I am not sure if there is any more info I can provide ?

Kurt.

 

[dogman dan]

The only thing that comes to my mind is that the 15s lipo is not providing the c rate it should.

Are you running a 5 ah pack at 60v, and a 10 ah pack at 36? Do you see voltage sag with 60v and no sag with 36? Mabye adding one more pack, is adding a pack with really high internal resistance that cuts the amps? I'm totally guessing, but the only think that makes much logical sense is something about adding the volts is causing resistance in the whole system. Bad battery, bad connector, something like that.

 

[Kurt]

The only thing that comes to my mind is that the 15s lipo is not providing the c rate it should.

Are you running a 5 ah pack at 60v, and a 10 ah pack at 36? Do you see voltage sag with 60v and no sag with 36? Mabye adding one more pack, is adding a pack with really high internal resistance that cuts the amps? I'm totally guessing, but the only think that makes much logical sense is something about adding the volts is causing resistance in the whole system. Bad battery, bad connector, something like that.

Its not the battery's. The 5ah 20c lipo is in 2p 10ah for both 36v and 60v I am lucky to get 1v sag at 40amps. The difference between 36-60 isn't as apparent as I first thought. I believe the issue is still there at 36 but just not as noticeable. Like I said in a earlier post .Its not high resistance in battery or wiring as it can provide 40amps but only at high rpm.

The video at 36v and the old one at 60v-rear facing camera is how it should perform. So i guess it can perform well at both voltages but it is more noticeable on 60v. The issue has got progressively worse.


The thing I am 100% sure on is that the controller no longer has the ability to draw high amps at low motor speeds . It only has the ability to provide amps in the upper rev range of the motor

In short the controller is still working but is quitting out "providing 10 or so amps' No where near its rated current of 40amps. I take it low rpm high load is the toughest condition a controller can see.

I did a test tonight with the drive removed and mounted to the bench. I had a 36v feeding the controller and had the motor ticking over at say 15% throttle . the no load amp draw of the motor was perhaps 2amps. I them grabbed the motor letting it slip in my hand.I then tightened my grip some what and gave it some throttle to simulate a load. I was able to slow the motor and even stall it even after applying full throttle. The CA only showed 8 - 9amps before it stalled.

Now all things running how they should that 80-100 should have almost ripped my hand off and the amps should have shot up to at least 20 -30 amps. i remember when I first bench tested the motor a few months ago. I had the motor running at about 60rpm mounted to a wooden block. there was no way in hell you could stop it with your hand, Even at 60rpm! Some controller same battery.If I was to run the same test now I think my 4yo daughter could stall it.

So what can happen to a controller-fets? or whatever that will allow the controller to still work but have this condition?

If there is anything more I need to test or info let me know.

kurt