TREX500E throttle dropping out

[getsuyoubi]

I have a stock (though flybarless) 500E, and I noticed the throttle dropping out for a split second two times this morning. The heli dropped 2-3 feet before the motor caught on again, so fortunately nothing bad happened. The same has happened once a few weeks ago. I fly scale-like, slow circuits.

Equipment:
- stock Align 70A ESC
- CC Pro BEC
- stock Align 500MX motor
- 12t pinion
- flat 85% throttle curve
- Glacier 6S 3300mAh battery, with ~40 flights on it
- timer set to 7min; putting ~1800mAh back to fully charged

I'm aware that the Align ESC doesn't have the best reputation. Is this behavior one of the known problems with that ESC, or would you suspect something else?

[Abenn]

I had a similar thing a couple of years back with my flybarred 500 with stock Align ESC, but the duration was so short I didn't lose any height, but noticed a quick tail-kick instead. I thought it was gyro or tail servo at first, but then on about the fourth or fifth time I noticed the momentary change in motor noise when it happened.

Swapped the ESC for a Talon 90, and haven't had it occur since.

[getsuyoubi]

Well, that's "good" news then - sorta... At least I know more or less for sure now what to swap out...

[SumOFparts]

I've actually had a change of heart on these align 70a esc - they seem to be very robust - they just have zero program ability -

I would check the solder on the bullets - connections and what ever before throwing the esc to the dogs.....

I've heard of problems on the original 500 60a esc - but not any on the 70a one - they even put these in the earlier 550 kits....

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[getsuyoubi]

That's a good point, but why would that suddenly happen after ~200 flights? On the other hand, I did relocate it from underneath the battery tray to the side a few weeks ago when I moved my FBL from the tail boom case to the front. So I cannot really claim that I never did anything to it, though I wouldn't know what could have gone wrong.

[SumOFparts]

I had a 500 with maybe 50 or so flights on it - then at mid flight it would lose power to about half - when I'd land the CC esc would be beeping.....couple more times - it wouldnt even spool up without a shutdown....

Turns out one of the motor bullets had come unsoldered - only found that bullet amiss when I pulled the motor.

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[getsuyoubi]

That's interesting.
Thinking about it some more, it turns out that both instances (a few weeks ago and yesterday) most likely happened on the same battery, though I'm not perfectly sure. But there may be more to it.
I always parallel charge my batteries at home, at less than 1C. At the field, I re-charge (also parallel) them (after flying and appropriate cool-down) at 1.5C - and I know for a fact that both times the drop-outs happened after re-charging at 1.5C! So, maybe it's a battery cell going bad?
I charged them separately today to see how much they take, and I don't see a difference between batteries. IR is also similar, so no smoking gun there either. I guess I'll have to see whether it's indeed always the same battery before swapping out the ESC.

[Gladius]

I had the same thing happening on my 600. I found a mark across the motor windings where it looked like the edge of something had been pressed into it. I swapped out the motor, and the problem disappeared. But unless you've crashed recently, I doubt your problem is your motor windings! I would carefully check all your bullet connectors, and if you can, see if the wires going into the ESC are coming loose too. Since you just moved the ESC, I'm guessing that is where your problem lies.