Overheating, bad ESC, shorting out, or just normal operation

[muddyml]

I'm having trouble staying in the air longer than a few minutes. The voltage before flight is 4.21V but its dropping out of the air after a minute or so even with full throttle. When I measure the voltage after this happens its always been reading around 3.85-3.94. Its almost like the low voltage cut-out is set really high or something. It's flying just fine and then all of a sudden it just starts cuts out. I can't even give say 70% throttle at that point. Its all or nothing. The motor is either stopped or is spinning as fast as the ESC will let it. There is no middle ground even with the trim. The funny thing is once while I was landing on full throttle while this was happening as soon as the landing gear tapped the ground it decided the voltage was just fine and it shot up like a rocket at full throttle.

Its a Walkera 4#6s that I've upgraded with a XP-7A-2 EBAY BL Programmable ESC and a TurboAce 915-14 motor, using a linear 25C 650mAh 1S battery. I have two batteries and it happens on both of them. All parts came from WOW. In reading the ESC the LVC can be set to 2.6, 2.85, or 3.1v and it also has an protection funtion the will reduce power to 50% when low voltage or overheat occurs. I've left all setting on the default so far.

I'd like to get some more knowledge or opinions on why this is happening. How do I determine if I maybe have a bad ESC, bad batteries, maybe a bad connection somewhere, or either the ESC or motor is overheating? IMO the motor has never been hot to touch, I'll get out my laser thermometer when I get home tonight and see if I can grab a few readings. I'm still learning to fly really so I'm just practicing some nose in and side in hovers when this problem happens.

Thanks in advance for the help and comments.

[john aeras]

I would start by testing a new battery. If that doesn't change anything, I would play around with the esc.

[1sickvibe50]

have you had any bad crashes? did the heli always do this?

[muddyml]

Good question. This started when I upgraded to this esc. My old esc would no longer turn the motor over so I upgraded to this programable esc that can handle more amps.

The motor was cool to touch but the esc was warm/hot. I keep thinking its some setting on the esc but I get no where near the lvc voltages it gives as options and don't know what other setting it could be. I really don't want to spend money on another new esc of the same model or brand either but I don't think I have many options if I do have to replace it.

Batteries never get more than warm and its happening on both battiers I have.

Thanks again for everyone's help.

[muddyml]

Here is info about the esc.

Parameters: (* in front means only configurable by LCD Programming Card, other settings can be configured by a transmitter)

1. Brake: Off, soft brake, and hard brake
2. Timing: low, middle, and high; default is middle
3. Startup mode: fast, soft, and ultra soft. Fast applies to low-inductance and start-load motor; ultra soft applies to high-inductance and start-load motor; soft applies to case between above two
4. Protection function: select from reduce-power or cut-off, default is reduce power. In reduce mode when overheat or low-voltage occurs, output power will be reduced to lower than 50%
5. Throttle curve: 3 different curves for throttle control
6. Li-xx cell number: auto detect or manual selection
7. Cut-off threshold: low 2.6v, mid 2.85v high 3.1v
8. Motor direction: normal or reverse
9. *Starting power: to set the ratio of output power when starting in the range of 00% - 39%, default is 00%. Under default setting, output power is decided automatically by the system according to throttle stick position
10. *PWM frequency: 13KHz and 8KHz, default is 8KHz. 13KHz is an option for low-inductance motor
11. *Low voltage threshold: user can set proper voltage threshold according to cell quantity in the range of 00.0-49.9V

[john aeras]

Is that motor an in-runner, how long have you had it? Did it use to heat up alot? If so, the motor may be the problem.

[muddyml]

No its an out runner motor and it usually stays pretty cool. I actually think i solved it by cutting a whole in the canopy over where the esc is mounted. I haven't noticed it since at least. *knock on wood*. I think since this esc has a higher output capacity than the stock one I had that my batteries are just draining quicker too. I use to be able to fly safely for a minute after it needed 80% throttle to hover. Now as soon as I notice it starting to require more throttle I bring it in.

Bigger out runner motor than stock = shorter flight time
25c battery vs 15c battery = more power availability but also shorter flight times
New esc has a higher output current than stock = shorter flight time

Does any of that make sense or am I just convincing myself that I don't have a problem? I actually hope I didn't ruin any of my batteries because of this. I guess at $12 a battery its not the end of the world if it did anyhow.

[Nytflyer]

I am not speaking from experience here with this particular heli and setup. But seems to me the XP7a might be a little to light for this application?

Guys over in the mcpx brushless threads are using this motor with the xp12a so just something you might want to look into. Hopefully someone with more knowledge will comment and help you out.

Good luck!

BTW : I have been flying walkeras for years and I like their 10a ESC over the xp7a in many applications.