[Garagepro]

I just installed a new HobbyKing 2200MAH 3s Lipo in my E-Flite Stinson and when I give full throttle the motor hesitates,then revs up and then slows down again.It does this continuously. What would cause this.The battery is fully charged,about 12.4 volts

[philipa_240sx]

Do you have another pack you can try? This will at least allow you to determine if it's the pack or the motor/ESC.

A bad pack, poor connection, or a bad solder joint could cause a high resistance connection. Although the pack voltage reads fine with no load, the voltage could be dropping under load causing the LVC to kick in and slow the motor.

[davidmc36]

What are you using for ESC?

I just had this happen yesterday with this ESC.

I found it happened when I punched the throttle quickly to full but did not happen if I brought it up slower. Batteries were freshly charged and deliver full volts and amps at full throttle. It just does that 'surging' thing when I punch it right up to full throttle.

The ESC I have is used and I was wondering if the previous owner had changed some settings. My first thing to try is setting it back to defaults.

The surging that mine does is on about half second frequency.

[uberjay]

The surging sounds like the LVC (Low Voltage Cutoff) and, yeah, it can be programmed to taste with different ESC's. The odds are though like Philip said that it could be a bad solder joint.

Or, you could have a bad cell in the pack. On a smaller scale I had this happen with a 180 mAh 2S battery... I could read a voltage on one of the cells, but the other went completely dead - after exhibiting similar symptoms to yours.

Anyway... +1 on Phil's idea of eliminating the culprit by using a known good battery, etc.

Cheers,
J

[davidmc36]

Originally Posted by uberjay

The surging sounds like the LVC (Low Voltage Cutoff) and, yeah, it can be programmed to taste with different ESC's. The odds are though like Philip said that it could be a bad solder joint.

Or, you could have a bad cell in the pack. On a smaller scale I had this happen with a 180 mAh 2S battery... I could read a voltage on one of the cells, but the other went completely dead - after exhibiting similar symptoms to yours.

Anyway... +1 on Phil's idea of eliminating the culprit by using a known good battery, etc.

Cheers,
J

It can't be a programmed LVC with mine since the highest that can be set is 3.2v/cell and the 5S battery never went below 19.3V at 54 amp load.

It only happened when I put the throttle up quickly. If I took about 1 second or more to raise to full throttle it did not happen even after holding at full throttle for several seconds.

I don't see any problem with the battery power.

Has anybody had this issue and fixed it with a ferrite on the ESC to Rx lead? When I got this from original owner there was a ferrite on it but I wanted the extra length unwound so I took it off. My other ESC identical to this one did not come with one on it when I bought it new.

[uberjay]

Originally Posted by davidmc36

It can't be a programmed LVC with mine since the highest that can be set is 3.2v/cell and the 5S battery never went below 19.3V at 54 amp load.

Yeah... I know the Turnigy Plush series allow you to adjust it. Not trying to make a blanket statement, just a suggestion if you hadn't already tried it.

Originally Posted by davidmc36

It only happened when I put the throttle up quickly. If I took about 1 second or more to raise to full throttle it did not happen even after holding at full throttle for several seconds.

Hmmm... I wonder if either the timing or soft start settings have been altered?

Originally Posted by davidmc36

Has anybody had this issue and fixed it with a ferrite on the ESC to Rx lead? When I got this from original owner there was a ferrite on it but I wanted the extra length unwound so I took it off. My other ESC identical to this one did not come with one on it when I bought it new.

I'm pretty sure the ferrite is to help eliminate EMF / noise on the signal line. If it was on there before it's probably best to keep it on and just get an extension for the extra length you need. I had an E-flite 40 Amp PRO series ESC come with it too. All that said, it doesn't sound to me like something that would cause the problem you're seeing.

Here's a question... do you see the same problem when you have _no_ prop mounted on the motor?

[Cougar429]

You do not specify if the ESC is an Eflite unit stock to the plane, real time battery voltages during running or what radio gear you are using, so the following are best guesses.

The ferrite ring is used to eliminate or reduce RF being introduced into the receiver from the upstream side of the ESC throttle lead, (the one wound into the ring). This seems to be more critical with 72MHz systems, but likely any that are sensitive can be affected.

That ring needs to be located as close to the receiver as possible as any amount of lead between the ring and receiver plug can reintroduce RF noise. Removing it simply means the amount reaching the receiver is the highest probable. I say that as all other leads running to the receiver can also pick up RF sources and servo extensions are notably vulnerable. If it came stock with one, likely it is required and a good idea to reinstall it. If you need the length, wind the ring into an extension as close to the receiver as possible.

As for noise sources, the largest will be the ESC/Motor leads themselves and the internal switching circuitry within the ESC itself. The larger the currents the more RF is generated. With an integral BEC you provide a closer link between the switching, leads to the motor and the signal/power source to the receiver. That's the reason on higher power systems I opt for a separate, good quality switching BEC.

You can try to maximize the separation between the ESC, motor leads, servo leads and the receiver and attendant satellite and/or antenna(s).

One other reason for hesitation may be a timing issue between the ESC and motor. The faster you try to ramp up the throttle the quicker they can fall out of synch. If you can alter the programming you may want to change the selections for timing, (I'm also making the assumption you are running the 60A PRO, which has 5 possible timing settings). That ESC also has the following characteristic, "Auto motor shut down if signal is lost or there is interference". You may also want to check if the
'soft Start" is enabled.

Finally, even though you have a new pack you do not list the C rating. The current demand on fast throttle up may simply tax the output too much. That's why an inline meter with accurate, real time data on currents and voltages is so useful in these situations. To be honest your info regarding the 5S does not help much here as my primary suspicion is the battery voltage falling off.

More info may be needed to narrow this down. If you can, add the make of radio system, ESC and programming options enabled.

[davidmc36]

Thanks for all the input here. First thing I am going to do is hook the programming card up to mine and see where things are set. I would like to eliminate if it is a timing issue. The 4020-14 says 5deg timing and 8khz drive frequency. Both are adjustable on the ESC, maybe they are wrong.

Next will be trying without the prop. Even though the graph from the run-up tests shows good voltage all the way it also shows a peak amperage of 75 when first starting the prop. Maybe that surge is causing a marginal solder joint to break down and voltage right inside the ESC is dropping below LVC, even though the battery stays well above.

250 amp rating on the battery so I don't see an issue there.

I don't seee any point in using the ferrite unless a problem with stray EMI is identified, it never came with it new and the other identical ESC that I have has been running without it on my Spek gear with zero issues.

My ESC is linked in my first post.
On this plane I have a seperate NiMh Rx pack and on the other one that runs fine I use the internal BEC, but it does not draw as much current either (4S at 40 amps).

Swapping the two ESC's may be something to try just for comparison too.

Hope to have time today to get on the bench for some troubleshooting.

[Cougar429]

Sorry, I still cannot find where you linked your ESC in the original post. Perhaps my "Caffeine Low" light is on.

[davidmc36]

Ran it again. Checked the ESC programming and on the Freq. setting it was showing an invalid value. There should be only choices 1 (8khz) and 2 (16khz)but it showed a 9. I reset it to the 8khz that the motor says it is supposed to have and put auto timing (that was set to high, 22-30). When I got done this test it showed a 9 again.

Next going to try a test without letting it get into the surging situation. Then it will be swapping out with the other identical ESC and seeing what happens.

First part of the graph shows the surging situation, the second part shows where I ran it up slowly to about 2500 rpm then punched it to full. Ran fine like that. Ignore the 17,000 max rpm, it is the nature of the recorder that it can give goofy momentary spikes like that even when the motor is stopped. everything smooths out once the motor is spinning a bit at a faily constant rpm. Initially when I punched the throttle quickly the motor just started spinning quite slowly then after about a half second it quickly shot up in rpm (you could feel the plane torque) then back down again, then up again and so on and so on.....

Interesting this ESC says three timing settings, auto (7-30) low (7-22) and high (22-30). The motor says 5deg.