CC HV current limiting for free?

If you don't already have one to go along with your Castle Creations ESC, the Castle Link USB programmer is an excellent tool. It allows you to update the software on your ESC and super-fine tune all your settings like motor timing, throttle response, low voltage cutoff options, etc...

Specifically, the software allows you to set the voltage cutoff in 0.1v increments. It also gives you the option of hard cutoff, which cuts power entirely to the motor, or soft cutoff, which throttles the motor to keep the voltage above a certain limit. So I propose setting the cutoff type to soft and the level to something close to your expected voltage drop from your pack. For example, I would set mine to 31.2v for my 12s Headway LiFePO4 pack which is 2.6v per cell. This way, a hard pull will trip the cutout and automatically throttle your motor to prevent an over current situation. As the pack discharges, you will get less and less peak power until it's time to go home and recharge.

What do you guys think about using the cutoff feature like this as a current limiter?
Just a thought.

Hey Oof,

I purposely never mentioned this for two reasons;

#1 I did not want to confuse the issue.
#2 There is one problem with doing this. That problem is;

Most packs run down in voltage as the capacity drops. So, if you use the LV cutoff as a current limiting feature, you will find it works well with a fresh charge on the pack. Then, as the pack gets a bit low, the voltage and related sag changes and makes the cutoff occur much earlier. This makes for an inconsistant cutoff point. That being said, I will share my own experience with LV cutoff;

I used to run high speed RC cars (well over 110 mph). These cars typically drew 125+ amps from a single HV110 ESC. The HV110 can handle this because that much current was only drawn for 3 to 4 seconds at a time, max. Anyway, I tried the LV cutoff as a wheelspin (wattage) restrictor. It worked wonderfully if I kept a couple things in mind;

#1 It only worked well with a freshly charged pack.

#2 It took a while to get the exact cutoff voltage figured out.

I found the when the cutoff was set for soft and the exact cutoff point was found, the car was very controllable and the rolloff for the throttle (when the LV point was reached) was fantastic! It worked better than I ever thought, that was untill the pack ran down a touch and was now 1 or 2 volts low. Then the LV cutoff kicked in too soon.

So, my opinion is---- Yes, it works. But, you need to be advised of the limitations.

Matt

I knew you would have tried something like this already, Matt. Thanks for the input.
I'll give it a try anyway as soon as I get my mounting situation figured out.

Are you running Vista? I FINALLY got my Castle Link software installed on my Vista operating system. Previously, I had to use my old computer every time I wanted to update anything.

My next bike is running two HV110s. It will be a time consuming pain to setup both to the exact same settings. But, it is doable.

I think you will have decent success with the LV cutoff idea. It worked for me.

Matt

Oh, you gotta stop by in a week or two so you can check out the bike. It is really coming along!

TWO HV110s? Are you serious?
Nope, I'm actually running it in a virtual machine running Win XP on top of Linux. Works great.

I'll try to make it up there again in the near future. I wish I had a working ebike...

Vista....

When in doubt, right hand click, "Run as Administrator"

If that does not work, uninstall, then run the installer as Administrator.

I have been running Vista since day 1 and have never found a program that would run on XP but not on Vista.

-methods

I am almost 100% computer retarded, though.

For me, this was an accomplishment!

So, Meth, how goes the Cyclone? Got it all debugged and running yet?

Matt

Yea, I got it running last week.

At 48V 100A the thing is weak. (by my standards)
I rode it that way for a few days... pack sagging down to 40V due to the retarded current requirements just to make a lousy 4kw
I had to go to ABQ on business for a few days and I spent most of that time bummed.

When I got home I realized that I was being stupid. . .
I was running 48V because that was what the motor was rated at.
The windings are E class which makes them good to over 120 degrees C and I am SURE that they can electrically insulate to at least 100 battery volts

So I strapped another 6S4P 22.2V 20A pack in series as a booster pack
That put me at 18S4P 66.6V 20Ah, 75V off the charger

At 66V 100A that thing punishes! I was making 6KW rips past the 45MPH radar by my house and it was blinking "SLOW DOWN"
I am running a 9 speed cluster with indexed gearing and I can BANG through the gears even under 6KW of load.

Whoever said that you cant shift a non-hub motor with an external cluster obviously never tried it

My indexed shifter just punch through the gears like perfectly machined clicks.
CLICK
CLICK
CLICK

When I want to up-shift I can ratchet 1 at a time or push up 3 gears on 1 stroke

So.... Yes the Cyclone can put down punishing power. Yes you can use a totally standard 9 speed cluster with a retardedly high powered non-hub motor.

The catch is the heat. I have an 85 degree C thermal switch and it will pop when I ride it hard.
I need to get it instrumented with a proper temperature sensor and get some heat sinks on it.

sorry for spamming up the thread btw. Recumpence asked and it started a bout of verbal diarrhea for me.

-methods

Don't forget to tell them how it sounds like an F1 car when you blast through 9 gears.

On the phone, this is what Methods says his bike sounds like. This is why I MUST shift. MUST!!! I want 50Kw induction motor, and a bunch of gears. It's ok if having a bunch of gears makes me slower. It just MUST sound like an F1 car.


http://www.youtube.com/watch?v=TNIGnKZvPks&feature=related