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Old 06-12-2017, 01:53 PM   #1 (permalink)
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Default So what happens to a motor when you demand more?....

As I progress further and get better, I am trying to find out if my motor is undersized for my needs/ability...

HKII 4225-610kv. Manufacture says 80amp continuous / 3550watt continuous and 5770watt BURST.


Theoretically speaking, what happens to a motor when pushed beyond it's limit of current handling capabilities? (I've not gotten there... YET)


Thanks,
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Old 06-12-2017, 01:59 PM   #2 (permalink)
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I don't have any experience with a 700 size heli but I would imagine it's the heat that kills them, or really with enamel coating on the windings that gets destroyed. Once the enamel comes off the windings short, not sure if it takes out the ESC or not. Best thing I could recommend is to inspect the windings every once in a while for discoloration.

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Old 06-12-2017, 02:15 PM   #3 (permalink)
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I should mention this motor does come down consistently at a temperature of 170f-190f after 4 min flights.

But this manufacture of motor is known to run on the hot side. I've never had experience with any other brand of motor.
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Old 06-12-2017, 02:22 PM   #4 (permalink)
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There was a thread recently that talked about motor breakdown. High current is going to lead to over heating which is going to lead to magnet breakdown that's not reversible. But most likely the reason for over current is the motor being under powered. When it can't meet the load demand the current will shoot up, so if you have the right motor for the job you should be OK.
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Old 06-12-2017, 03:39 PM   #5 (permalink)
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Quote:
Originally Posted by Raptorapture View Post
There was a thread recently that talked about motor breakdown. High current is going to lead to over heating which is going to lead to magnet breakdown that's not reversible. But most likely the reason for over current is the motor being under powered. When it can't meet the load demand the current will shoot up, so if you have the right motor for the job you should be OK.
I must still be within' range. my average current is around 70 amp for each flight with max bursts around 115-120amps

I am only basing my concern on motor temperature so I've certainly learned something today.

Thanks!
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Old 06-12-2017, 04:09 PM   #6 (permalink)
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Quote:
Originally Posted by Raptorapture View Post
There was a thread recently that talked about motor breakdown. High current is going to lead to over heating which is going to lead to magnet breakdown that's not reversible. But most likely the reason for over current is the motor being under powered. When it can't meet the load demand the current will shoot up, so if you have the right motor for the job you should be OK.
Under-powered or over-taxed. There's a difference. A good proactive governor can prevent most cases of over-taxing an amply powered motor, but if the motor is under-powered, there's nothing to do but go to a stronger motor and, possibly, more battery cells.

It's my understanding that the newer Scorpion motors run cooler than the older ones. I don't know why you were afraid to mention the brand name when everybody knew what it was. I've stayed away from Scorpions because of their history of excessive heat buildup; to me, it means that a lot of power is being wasted. I've been exclusively running the brand with the big X on it.
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Old 06-12-2017, 07:34 PM   #7 (permalink)
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I still have two helis with scorpion motors and not by choice. My 700 will be the next for a motor change. My Trex 500, I can care less. My choice for motors is xnova. The difference in power is much better than the scorpion motors.
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Old 06-12-2017, 09:23 PM   #8 (permalink)
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Excessive heat not only tortures the winds, but damages the magnets rather quickly. The higher the mag quality, aka costs of purchase, the more heat resistant and higher magnetic signature they provide. It isn't all in the winds.

Also, it isn't all related to motor size. I have friends that can smack their helis around twice as well as I do, but using smaller output motors than I run while doing so. Their collective management is just superb! One, a good bud who is sponsored is running a Scorp ultimate I benched out of one of my Gob 700s thinking it was modest power wise myself. Has it in his new Logo 700, and has plenty of power and still makes me look like a beginner with my gen 3 Kde in place on my own (now 14s) Gob 7. He averages 3 1/2 min flights and tortures new batts, I watched him puff a cell in his newly recieved pulse 12s pack while doing so last week. The motor is quite happy, but he is considering a 14s upgrade soon as his 14s 766 with larger Scorp motor flies longer and comes down cooler doing the same routine. Batts aren't cheap.
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Old 06-12-2017, 10:51 PM   #9 (permalink)
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Something to remember is that the voltage across the motor has to do with how fast the motor is turning; the motor acts as a generator, and produces a voltage that opposes the supply voltage. When a motor sees full pack voltage (100% throttle) at high RPM, the current it flows is much lower than the current it flows at 50% of that RPM. Current may double because the motor BEMF drops in half etc. But two problems here. One is that once the motor sees some (motor specific) high level or current, its magnetic system saturates; more current doesn’t increase the field strength, and huge currents can flow as a result. Another is that heat in the motor is a function of the square of current. So you get dramatically higher heat generation. This is why you don’t fly around at higher power settings at low (relative to Kv) motor RPM- you burn too much current, and create too much heat.

So, you can have a situation where you are geared correctly- and the motor simply cannot produce enough power to generate more thrust. But it may still live within its thermal limits there. Another situation is where the motor RPM drops a bunch, current increases dramatically, and the motor burns up- even if it is producing less output power (more torque, but less RPM, and power is torque * rpm).

Point here is that it depends on how you define ‘undersized’. In one scenario, nothing bad happens. In another, very bad things happen very quickly.
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Old 06-12-2017, 10:59 PM   #10 (permalink)
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Default Your on it ! But why ?? It's a Vicious Circle : Respect EM

As working load goes up - " due too Lot's of Conditions " bearing's drive trains . alignment. operation conditions, - full of dirt / product // parameters ect

These motors : They take inc-readable abuse - Designing for it !

With work load going up - it's efficiency goes down . It builds HEAT - These are NOT continuous duty cycle motors. Constant load - Yet you can almost get them their with the new Logic.

Ramping the timing or SMART EM to guess what's coming " Program EM.

Many continuous motors actually have internal governors to prevent run away's.

They will try to get their !

These are Permanent Magnet Motors - Hybrid's : They are Heat sensitive. ALL

When resistance goes up -" LOAD " - So does HEAT ! 1st thing that begins to break down is the lacquer coating on the winding - Gets thin do to heat - Oxidized OFF .

Then you get a Fault or voltage cross - " NOT using the Full Winding - The STINKO

The viscous cycle begins / Till Failure or winding coatings completely fail. POOF.
or the magnet forces break down or the adhesive failed. The POOF !

Best care ? Keep em CLEAN & Keep em in their play pen where they like it ! Stay in the proper operating parameters !

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This is { CRAZY HORSES - ONE SOCK } Still got it MATT ! { One Sock Crazy Horse }

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Old 06-13-2017, 08:35 PM   #11 (permalink)
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So if you look at the specs thats 5700 watts at 5 seconds but if it were to have its 2 second max listed it might equate to 7700 watts and that's about the wattage of a 4035 which is the 750mx which is used on 700s

not sure why some motors specs are listed at 2 seconds max like the 4525, 2 second max is about 10,000 watts but if they listed its 5 second max it might only be 8000 watts


I think a lower kv or ratio change may help with the temps

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Old 06-14-2017, 11:52 AM   #12 (permalink)
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Overtaxing could lead to a catastrophic meltdown but that does not happen all that often/fast.

I am overtaxing the scorpion I have built into my Protos 500. It runs hot in stock configuration with 430mm blades but it has to work on 480mm Zeals for quite a while now.
Overtaxing like this leads to bogging mostly wich is quite annoying.

I got a MX850 11kw peak motor in the 700X and the flight experience is a whole different one. Having an abundance of power is nice because the headspeed wont ever bog no matter how hard you are on the collective.
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Old 06-14-2017, 12:52 PM   #13 (permalink)
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Thumbs up Can some one explaine WATT's ? Thought it was a measurement of Horse Power

So if you look at the specs thats 5700 watts at 5 seconds but if it were to have its 2 second max listed it might equate to 7700 watts and that's about the wattage of a 4035 which is the 750mx which is used on 700s

not sure why some motors specs are listed at 2 seconds max like the 4525, 2 second max is about 10,000 watts but if they listed its 5 second max it might only be 8000 watts


????Based on OHM's Law ? Amp's X Volt's = Watt's

How are they achieving the Volts and the Amps ?

Watt's was alway's a Theoretical Math measurement of Horsey Power = How Many Horse ?

Like a 10,000 Watt Light Bulb or 8000 Watt Light Bulb

How are they doing it ????
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Old 06-14-2017, 01:56 PM   #14 (permalink)
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I ran a protos 880kv motor on my gaui x5. It worked for a long time. What happened was the motor got stupid hot. But it didn't bother it much. After a while I demagnitized the magnets. The motor still worked but didn't have the power. Then the bearings failed and the experiment stopped.

I replaced the bearings and can and it was as good as new.

The beauty of brushless motors is that there are no moving parts.
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