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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Steve Hines on August 14, 2013, 08:59:32 PM
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I don't know what happened, Samantha went flying on Sunday with no problem, got home and charged batteries and to night went out and the motor went about 2min and then went to a very low RPM and stayed there. She landed with the motor running and I had to shut off the switch to stop it. I put a different battery in it and it did the same thing, but this time stopped on its own. It did not do the off and back on to let you know that is was going to stop. Both times it was in the up part of the outside square. I reset the time and did a test flight and it was fine, did the hole pattern the next time with no problem. I don't know what happened. Has anyone had this problem?
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Hi Guys, My timer system has a proven track record these days with hundreds in use now, so when something like this happens and the motor does not speed up after the go-slow indication or slows down and dies before the preset time, then it is usually the esc shutting down due to low voltage. I'm not sure why it's an "adventure" Motorman, when you try to change anything?? Sure the programming card is basic and has no LCD display or anything, but then it does not cost much either, and many of the users "set it and forget it", and don't enjoy changing settings a lot with display boxes and/or pc's. Some of the lower cost esc's have "not so clean" switching voltage regulators (SBEC) in them and none of the timers with processors in them like to work with spikes on the power supply. As far as I am aware, RSM has sorted out that problem now.
So now Steve, it looks like something could be wrong with your batteries and if you have a battery checker that is the quickest way to make sure after the flight to see if there is enough power left in the lipo. Most chargers these days have a function for checking each cell in the pack as well. I do this by doing a quick discharge on my Hyperion charger and then I can see if there is a problem. It sure is simpler to get a modern battery tester with a display from you hobby shop or Hobby Kings if you prefer. For electric flying this is a great tool to have. If your setup flew without problems before then I would certainly suspect the batteries or charging of them. Please keep us posted. Thanks.
Keith R
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Keith when I got home I tested them both were at 15.88 volts, I did a balance charge and they took just over 6ooma. I just don't know what happened. nothing has been change in over a month. Maybe thirty flight at this settings. there has not been a problem before. It has a trust esc, don't know if this could be the problem. I used this because other's said this was a good set up.
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It seems the Trust ESC is a Hobby King rebrand of the ZTW ESC. At least that what was said on one of the R/C forums. My experience with the ZTW ESCs and been very good, I use them in several of my planes with the KR timer/governor. Which model of the Trust ESC do you have, it would be interesting to see if it does have an SBEC. As Keith pointed out we did have issues with one brand of ESCs and traced the problem back to spikes on the BEC voltage caused by the switching regulator. Can you post a close picture up of the installation, I would like to review exactly what you are using.
Andy Borgogna
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My experience with the KR timer has been very positive. I have about 500 flights on two systems using KR2 timers with 55amp Turnigy Trust esc's (4 or 5 cell battery and Eflite 32 or Eflite 25 motors) for the past year and have had no timer or esc related issues. Everything runs cool and efficiently. I run the KR2 at the maximum gain setting. I think I would look for a connector or something that might be reducing the voltage available to the system...as the battery appears to be okay. A couple years ago, I had a similar issue with a cold solder joint on a battery connector. I also have had a Castle Phoenix (Ice Lite) do that when I had a battery that developed high internal resistance.
FWIW, Bob
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Steve,I don't think the timer is the problem.Did you plug the battery in with the switch on?This can change the ESC programming without you meaning for it to happen.It goes through a startup when you plug the battery in and if the switch is on it interrupts that and in your case you may have changed voltage cutoff.My buddy Ron has a problem with his arming plug not working correctly and he managed to turn on the reverse rotation by accident.The Turnigy Trust ESC and KR2 is a very nice match.You can truly get champagne performance with a beer(Pepsi) pocketbook.
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I have a few hundred flights on my KR Timers and I change the revs often. To the extend that I don't even use a tach; I know one click up or one click down changes the revs by 60 (on my motor) which affects the lap time by .05 seconds (on my lines). Now and again I might change the flight time when I am testing. I never change the Gain it has been at 4 for the past year.
I have not had this problem of the motor slowing down but I would agree with the comment from Jeff Traxler that you may have plugged the battery in with the switch on. Simply reset the timer top revs range as it says to do it in the KR instructions and then all will be well again. Actually it sounds as if you found the solution since it is working now.
The only problem I ever had with an electric power system was due to a poor soldering joint (on the arming switch side where the battery plugged in) which worked loose, the shrink wrap held the connection together but it gave intermittent power problems.
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yes I did plug in the battery with the switch turned on, and it was just before I had the problem. It has been working great, it is just the way you set it up Jeff. I will now go thru and checked everything. I just got my programmer tonight in the mail. Yes it is a SBEC at 45 AMP. Thanks for all the help guys.
Steve
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Cold solder joints are very bad. They generally happen when you try to cool the solder too quick by blowing on it or dabbing water on the hot connection. Also if the wire to the connection moves as the solder is solidifying the joint can go cold. You can always tell a cold solder joint by the matte gray surface to the solder, if the solder is not shiny it could be a cold joint.
Now why is a cold solder joint bad? Well it no longer really a connection it's a resistor, and as Ohm's law says current through a resistor will drop voltage. A good solder joint should have virtually no resistance. Also as the voltage is dropped across the joint heat build up and over time will case the resistance to increase and make the problem worst. Every bit of voltage you drop across a cold solder joint is a bit of voltage that is robbed from the ESC, the BEC, and the timer. In short bad things can and will happen.
Andy
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Keith, I like your timers and will probably buy another one. I say it's an adventure because I have various results to my input commands. It's suppose to be 10 sec for every blink but mine is somewhere between 7.5 to 12 sec per blink and it's never the same twice. I have to take a guess on how many blinks to count out then test it. I finally lucked out and got it to 2 min 50 sec for the beginner pattern +4 laps. Also, setting the rpm didn't work, I followed the instructions but the rpm wouldn't change except for once when it did respond, I quickly set it and haven't touched it since. You say they've got the bugs worked out of their systems, I'm glad.
MM
Hi MM, that is weird! If you can try another esc and let us know, that would be nice. It sure sounds like the power from that esc is like the one I tested and has bad smoothing on the switching voltage regulator. This will do that sort of thing......and worse!
Keith R
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yes I did plug in the battery with the switch turned on, and it was just before I had the problem. It has been working great, it is just the way you set it up Jeff. I will now go thru and checked everything. I just got my programmer tonight in the mail. Yes it is a SBEC at 45 AMP. Thanks for all the help guys.
Steve
Hi Steve, I make the program in timer so that with the switch ON and when you plug in the battery, it puts out a full throttle pulse width. This starts the esc program mode as Jeff rightly says. You need to switch in OFF once you hear the short beeps and this calibrates the throttle range of the time to that of the esc. Looks like I need to add something in the instruction manual about leaving it on too long. Thanks for posting this, and I'll have a look into what could happen.
Keith R
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Hi MM,
Just a question on your KR timer system. What motor and rpm were you running when you experienced the erratic time settings? I'll tell you why I'm asking. If you are running a low rpm, below the recommended 7500 then the pulse width from the motor pick-up wire is too wide and the frame rate of the throttle pulse width jumps over to another frame, or out of the standard 20 milli-second frame rate. This will cause the problem you experience. It also happens if you use a low pole count motor like the Plettenbergs with 10 poles. So please let me know if you don't mind. Thanks.
I do have a program working now for low rpm use on the Pletty's that is being tested now, and this also seems to work on the low rpm/big prop stuff for the indoor foamies.
Keith R
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e-fight 15, 10-5.5, 9800 rpm
Steve