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Sep 19, 2021, 09:37 AM
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Helicool's Avatar
Hey All, I’ve been flying my Assassin on 3S with a T-Motor F80Pro/2200 with a 6.5x6 APC -motor always came down a bit warm but the performance was great, finally cooked the motor.

I wanted to try ‘more’ so I cut a prop to be a 5x6 and went to 4s - Propcalc said 36A, I measured 46A on the ground, tossed it up anyway and it only was in the air about 20 seconds - motor cut, landed safely, and the motor was cold but dead (spins erratically, likely lost a phase) -I just tried another motor, ESC is fine.

I assumed that the motor would overheat before there were any issues, but it never had a chance to get hot -can anyone tell me what happened here?
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Sep 19, 2021, 09:42 AM
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stillbents's Avatar
Thanks Hard Line....you are correct on the motor being a 2826. No idea why I left that out - I had picked a couple of them up years ago and figured they'd work well for the Assassin. Heading to the field in a couple of minutes but will look into ecalc later. I'll continue with the 7X4 today and pick up a couple of 6" props this week to try next weekend.
Sep 19, 2021, 09:47 AM
pull up -- PULL UP!!!
@ Helicool, I agree with you. Overheated motors don't cool off that fast. And an F80Pro can handle a lot of power, so dunno. My guess would be loose or broken wire over a burn out. Can't see anything?

There are ways to probe the windings with an ohm meter.
Sep 19, 2021, 01:08 PM
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alexbn921's Avatar
Must of fried something in the motor. Sometimes a gust of wind can pull extra amps on a maxed out motor overloading the windings

Just looked up the F80pro and it's a monster of a little motor. I would contact warranty on it as it shouldn't have failed on 4s in that short of a flight.
Sep 19, 2021, 02:22 PM
Registered User
Agree, the F80 Pro 2500kv pulls 60a on my Widowmaker all day long
Sep 19, 2021, 09:24 PM
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Helicool's Avatar
Quote:
Originally Posted by hard line
My guess would be loose or broken wire over a burn out. Can't see anything? There are ways to probe the windings with an ohm meter.
Thanks Hard Line, everything looks fine from what I can tell, and all wires have continuity, so I’m a bit baffled.
Sep 19, 2021, 09:39 PM
pull up -- PULL UP!!!
So you tried a different motor on your esc and that worked.
Just for grins try a different esc on this motor. In fact, do you have another plane with the same connectors and you can just hook this motor up to another full set of electronics and hand hold the motor during a bench test? If there's a cross mount on the motor, I sometimes grab that with a vice grip. Or you can stick two metric screws into the back of the motor and grab both with the vice grip.

Apart from what you might learn there, I've always found a stuttering motor to be a broken wire. Any chance you have an intermittent one for some reason?
Sep 19, 2021, 10:48 PM
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Helicool's Avatar
Quote:
Originally Posted by hard line
So you tried a different motor on your esc and that worked.
Just for grins try a different esc on this motor. In fact, do you have another plane with the same connectors and you can just hook this motor up to another full set of electronics and hand hold the motor during a bench test? If there's a cross mount on the motor, I sometimes grab that with a vice grip. Or you can stick two metric screws into the back of the motor and grab both with the vice grip.

Apart from what you might learn there, I've always found a stuttering motor to be a broken wire. Any chance you have an intermittent one for some reason?
Now I’m grinning… first I re-soldered the bullet connectors on both the ESC and motor just in case, had same problem.

I swapped to a different ESC, and the motor’s good 🤦‍♂️ ESC only has two flights on it, a Skywalker 60. Time to go see the guys at the hobby shop…. Thanks Hard Line!
Sep 24, 2021, 02:43 AM
Registered User
Never mind about LiHV batteries, now having problems, one almost blew up charging, others getting hot on recharge, I'm done.
Sep 24, 2021, 09:55 AM
pull up -- PULL UP!!!
I've bought a handful of LiHV batteries, small ones, because they happened to be a proper size for an application. Have had zero problems with them but I never go to the trouble of resetting the charger for HV. Just charge them to 4.2VPC like normal. Downside of this is not only do you not get any extra power from them (ie higher voltage) but you also lose some capacity as the rated capacity assumes a high voltage charge. I'm guessing a 1000mah LiHV will only have around 850mah with a conventional charge. But they are high C and deliver good current.

Rdimand, maybe try that with your remaining LiHVs -- see what you think.
Sep 24, 2021, 12:17 PM
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Helicool's Avatar
So… maybe 4s isn’t for me?

My assassin has been awesome on 3s with a F80Pro/2200 with a 7x6 cut down to 6.5x6 for about 45A - great speed, pretty much unlimited vertical, great control - comes down a bit warm -arguably I felt like I found my perfect combo.

but naturally I wanted to see if I could get ‘more’…. I tried it on 4s with a 5x6, and while it flies, it wasn’t the ‘awesome’ I was expecting. The 4s weighs the same as the 3s and are more than capable, and balance is spot on.

Am I crazy, missing something, or both?
Sep 24, 2021, 03:01 PM
Registered User
I have not had good success with props with pitch greater than diameter. I was excited to try a 5.25x6.25 prop…a dog.

Flew my F80pro last nite, 4S 6x5.5 awesome, I ran out of 6x5 props.
Sep 24, 2021, 03:59 PM
Lead On, O King
spectra's Avatar
I've enjoyed a few LiHV batteries, but they take more attention. I charge them to 4.20 volts per cell like hard line. Then, right before I fly them, push them up to 4.35 volts per cell. It's a nice punch on a fresh pack. But don't fly them down to empty. Try to land at 3.9 volts per cell. Otherwise longevity of the packs will be poor.
Sep 24, 2021, 09:01 PM
Registered User
RE LiHV:

I will try just to 4.2V, they almost seemed too good to be true, thin profile, light weight. I'll be happy if they just work well at standard voltage.
Sep 25, 2021, 08:56 AM
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Helicool's Avatar
Quote:
Originally Posted by Rdimand
I have not had good success with props with pitch greater than diameter. I was excited to try a 5.25x6.25 prop…a dog.

Flew my F80pro last nite, 4S 6x5.5 awesome, I ran out of 6x5 props.
Good to know, I’ll experiment further.


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