Is the Castle 120HV big enough to run a Scorpion 520 Ultimate?

[skunkworx]

Originally Posted by acidla

I also used to believe that by lowering the rpm would result in less amp draw. My telemetry system proved me wrong!

That's simple math. If the overall force needed to move the load stayed the same but you were using less voltage (aka, less PWM duration or switching) then yes. You would pull more amps. I understand perfectly well how more current means more heat, but not if my overall current and power draws are lower on Idle 1.

My point is that if your average current draw goes down from running lower headspeeds you net less overall heat buildup in the controller. I've already given examples of how much more heat I got when switching up to Idle 2, so how do you explain it if you think it's the other way around, RC/DC?

[RC/DC_5000]

It does really depend on how you fly it. If you fly it at lower RPM the way you were you flying it at higher RPM. You can be in for trouble.

There's definitely too many variables to say for certain what will happen every time. But lowering the throttle range can absolutely increase the controller temps and current draw. It was really more an answer to your question. Not necessarily your exact circumstances. You did ask.

If you'd post a log of when it actually shuts down... I mean that exact flight log. It would help. Or send the log to CC for them to review it. Their tech service is very good.

Is this helicopter governed? What gain?

[skunkworx]

From post #3:

Originally Posted by skunkworx

I don't have it governed. It's on fixed endpoints. I have the gear ratio figured out and the numbers are spot-on with the calculations. I have current limiting set to 180A/insensitive

Originally Posted by RC/DC_5000

It does really depend on how you fly it. If you fly it at lower RPM the way you were you flying it at higher RPM.
. . . But lowering the throttle range can absolutely increase the controller temps and current draw. It was really more an answer to your question. Not necessarily your exact circumstances. You did ask.

Is this helicopter governed? What gain?

I knew the answer before asking it. I was just curious about your thought process on the answers given. I've looked at the switching spikes on an oscilloscope and I've measured the effects of lowered throttle settings on speed controllers before and that's why I was saying the switching stuff doesn't add a significant amount of extra heat on its own. Again, lowered voltage with the same load means you'd get more current and heat, so that wasn't particularly what I was inquiring about. But it was an interesting sidetrack nonetheless.

On a different note, I switched the timing to 8kHz and went to fly it today and the TT stripped out on me again so I couldn't gets definitive answer on whether that might be the cause. But after chatting with a friend out at the field that definitely seemed to be the best course of action for now. I'll see what I can do about getting the logs off my computer. It's just odd trying to move a document from a desktop to a phone.

[RC/DC_5000]

Its interesting that a guy who knows the answers already while still asking questions doesn't have a 700 class heli governed and is wondering why its running hot. I honestly can't understand why any 700 helicopter wouldn't be governed. Unless you just built it and were tuning the tail maybe. You put a high output aftermarket motor on a helicopter and then you didn't govern it? That makes absolutely no sense. A mediocre motor on governor would outperform your high output motor with a flat TC. You're not adding throttle under load. Instead, the motor is just bogging down, drawing more current- just before it falls flat on its face in power output.

If you don't add throttle when you add pitch load.. the system loads up with current. Maybe your log doesn't show a critical current... but anyway you can reduce what you have will help.

Good luck.

[Magneto]

Originally Posted by skunkworx

You're understanding my issue in reverse. At 80% throttle I wasn't getting shutdowns. At 100% I am. The logs showed a peak of 124A on the highest spike and an average of around 56A, so it's all well within the limits of a 120A ESC, provided the sample rate is high enough (2Hz) so I should've caught at least a couple worse than that if it was an overcurrent issue.

I'm going to try 8kHz timing since that's the book value. I was using the outrunner mode so hopefully that helps.

Never use Outrunner mode its for high pole count motors! Use 8 khz with the Scorpion! This is your issue! I have seen this issue many times, That speedy will run that motor no problem and if your not a very hard flyer it will be sufficient amperage wise.

[skunkworx]

Thanks Magneto. I'm sure I'd be interested to know the reason why it wouldn't work, but Castle doesn't give you the degree of advance so it's a bit proprietary.

Anyway, I'm still waiting for the weather to clear up to give it a try, but I might get a break on Sunday if the hurricane swings south or runs out of steam by then. I'll post my results when I have them.

[skunkworx]

Well, Magneto it turns out you are correct. I switched to 8kHz timing and the highest recorded temp in four decent flights was a touch over 170°F and peaked around 137A.

So it's looking a lot more like the 120 indeed *can* support the 520 Ultimate motor. I still don't push it to the max, but at (5600W / 746 = 7.506 Hp) that's really nothing to sniff at!

[rcflyerheli]

It will probably take a little while for me to get my bird back into the air after swapping from a 160HV with fan to the 120HV on my 690SX with the Mikado version of the 4525-370 motor. My highest temp reading on the 160 was 94 degrees and my highest amp was 124.

When I get it installed and running, I'll post the log readings. I am running a 120HV on my X7 and initially with the Quantum motor, I was getting high temps (no shutdowns but about 30 degrees hotter than I was used to seeing on other similar helis). Switched to an Align 750 motor and haven't had any further issues. I also did switch to the formula canopy with the cooling vents in the front of the canopy at the same time.

[skunkworx]

I don't doubt that a 'bigger' ESC would run cooler. I just had the limitation of already owning a 120HV which I had paired up to a 4035-500Kv Scorpion. I previously never had any issues. But when I switched to the 520 I took the governor off and switched to outrunner mode for timing and it was shutting down even in a hover.

I'm not entirely sure why that mode was even put in there if it's that rough on your electronics. 8kHz seems to work great but I might try 12kHz just to see how much of a difference it makes.