NEW - ESC vs ESC

[kimmik]

Any measurement of temps? Was it at room temp no airflow?

[heliguyG6]

Be nice to see the YEP 120 Along side the YGE 120

[hidaven]

I have an eflite 25 amp esc that id like to donate.....

[jamin_00]

During these tests are you able to accurately measure exactly how many amps the Kosmik can handle at peak?

[Nitros83]

sub

[Asomaro]

I really appreciate the effort that you are putting into this.

Information like this is really important to try and understand especially as the size and power of electric powered airecraft is getting bigger and better all the time.

I've just put a yge 160 on my 700e and I can't wait to understand a little more about active freewheeling!

Cheers,

[ub3r]

20 seconds into torture testing the ICE HV80, it failed. The test was meant to consist of pulsing the load from No-Load -> Full-load (80Amps) at 50% throttle. It looks like the capacitor leads fused out, and the resulting input voltage ripples killed the FETs.

Check out the temp rise at partial load.

The footage is taking way more time than i initially thought it would.. but trust me it'll be worth it.

[sarpilot]

Well that is not good..... I have one of those on my 600


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[kimmik]

Pretty harsh test though. 160A motor current with 80A ripple in the caps of an 80A rated esc isn't a typical scenario. The fets would be dissipating 200W.

[rctintin]

Fantastic thread, just what we need in this hobby is independent testing, not the stuff the manufactures want us to read.

It would be fantastic if you could also test the Scorpion 130 V5 as they are getting very popular. Mine has been flawless thus far in my TDR with a hand wound motor.

[gadawg58]

Originally Posted by kimmik

Pretty harsh test though. 160A motor current with 80A ripple in the caps of an 80A rated esc isn't a typical scenario. The fets would be dissipating 200W.

I'm not real familiar with the logs yet but why do you say 160 Amp motor current. Looked like not even 80 amps or am I looking at the wrong scale? Thanks as I really don't know.

[Mercuriell]

Does sound a harsh test but not unattainable by any means in real life in a 6 or even 700. Maybe it was the lack of AFW in the CC that caused the problem. Would it be better to try the 100% throttle load test first in case the scenario repeats!

[Elios000]

there some were i can read up on what AFW is and does?

[kimmik]

50% throttle means motor current is 200% of input current, and motor voltage is 50% of input voltage.

80A and 44V input at 50% throttle is thus 160A motor current at 22V motor voltage.

You will never see this situation in a 600 unless your gearing is say 5 teeth too large, in which case you will indeed blow the esc or motor in no time.

160A motor current at 50% duty cycle translates to 80A rms ripple current through the input. The two capacitors cop the majority of this current, which is why one of them fused so quickly. Can you imagine 40A flowing in each 26awg lead.

A more realistic scenario, e.g. 80A at 90% throttle:

89A motor current
40V motor voltage
3.6kW
30A rms ripple current (rms is root mean square)
15A est. per capacitor
40W total freewheeling and i2r loss.

That's why this esc in correct use doesn't fail in this mode.

Even if you have freewheel, that esc will still fail in the same mode as the ripple current is same. the esc was tested at 2x current rating and 50% throttle, no esc manufacturer ever designed for that.

To make a esc survive that scenario, you need 1. A big low esc buffer cap bank, and 2. Afw to reduce get thermal 3. Lots and lots of cooling air.

[gadawg58]

Thanks for the info! Great Explanation!

[FireNWater]

Kimmick,

So what you're saying is that this was more of an "execution" than a "torture test".

[KU-HELI7]

I agree with kimmik. 80A input at 50% throttle is far away from normal use of a 80A ESC. Especially for ESCs without AFW.
But also with AFW this is more a test, like "How fast can I kill an ESC"

In general the test is very interesting, but I would suggest to change the test procedure, other than you want to show that AFW will protect an ESC quite a time against such load, which they have not really been designed for.

But that AFW is working well, is IMHO proofed enough with all Kontronik ESCs out in the field since the Jive was introduced some years ago.

Regards, Helmut

[ub3r]

Originally Posted by kimmik

50% throttle means motor current is 200% of input current, and motor voltage is 50% of input voltage.

80A and 44V input at 50% throttle is thus 160A motor current at 22V motor voltage.

You will never see this situation in a 600 unless your gearing is say 5 teeth too large, in which case you will indeed blow the esc or motor in no time.

160A motor current at 50% duty cycle translates to 80A rms ripple current through the input. The two capacitors cop the majority of this current, which is why one of them fused so quickly. Can you imagine 40A flowing in each 26awg lead.

A more realistic scenario, e.g. 80A at 90% throttle:

89A motor current
40V motor voltage
3.6kW
30A rms ripple current (rms is root mean square)
15A est. per capacitor
40W total freewheeling and i2r loss.

That's why this esc in correct use doesn't fail in this mode.

Even if you have freewheel, that esc will still fail in the same mode as the ripple current is same. the esc was tested at 2x current rating and 50% throttle, no esc manufacturer ever designed for that.

To make a esc survive that scenario, you need 1. A big low esc buffer cap bank, and 2. Afw to reduce get thermal 3. Lots and lots of cooling air.

Good Post Kim.

One would expect their ESC to at handle the rated current for more than 20seconds at 50% duty. Or would they not?

[heraldo]

Originally Posted by ub3r

Good Post Kim.

One would expect their ESC to at handle the rated current for more than 20seconds at 50% duty. Or would they not?

Very true. But then again, everyone knows better than to run an ESC at 50% excluding controllers with AFW


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[kimmik]

Depends on your definition of rated current i think. Is it input current at 100% throttle, or motor current at all throttles, or etc etc.

I would expect my 80A castle to take 80A motor current (rather than 160A) for 20seconds at 50% throttle (ie 40A input), but i dont expect it to survive for long even at this, which was why i posted my hesitation earlier about the test.

But seems it survived for 4.5min at 40A and 50% throttle in your earlier test, which to me is amazingly impressive already.

I was happy to see 20A 50% throttle as the normal test.