HZ Carbon Cub Reboot

[F22trainer]

HZ Carbon Cub acted up last time out. Took off flew to about downwind and power loss.
Reduced throttle and nursed it back with short bursts of power. Thinking maybe the battery got mixed up with my “charged group” I grabbed a fresh charged battery just to check. Ran it up to full power for a bit, ran for about 10 seconds and stopped. Reduced throttle and tried again- sane result but a shorter run.
What gives? ESC failed?

Anyway, I already have a new eFlite Park 480 and recommended eFlite 40 amp ESC, also new and looking for an airplane. Was going to put it in a different model, but won’t get to that build for awhile. Recommended battery size is same, but the HZ ESC is only 18A and the motor is only described as 480 with PArk Zone / HH markings.
Again, what gives? Would this set up work well in my HZ Cub? I think the motor will fit OK and ESC as well.
Never had any motor/ESC failures yet so looking to you guys for some symptoms and or fixes.

[fhhuber]

Put a wattmeter on it...

Feel the connectors to see if they are getting hot. Bad solder joints getting hot can turn into resistors. (shortly before the solder melts and you end up with no power at all)

Also check for the ESC getting hot. It could be triggering a thermal shutdown.

How old are the batteries? Old batteries can fail to deliver anywhere near rated current after just seconds, but still test out at >70% rated capacity under low demand.

The symptoms are consistent with LVC. or a thermal shutdown.of the motor side of the ESC.

Can't hurt to try the higher rated ESC (probably not a motor issue)

[rifleman_btx]

Sounds to me that the esc is having a thermal issue, i think if the connector was at fault you would probably loose all control. If I were a betting man either you have a failing mosfit, or if the prop is big enough over drawing the escs amp rating. I think I would also follow his suggestion of upping the esc. That's honestly what I would do. That takes either issue out of the equation.