/dist/images/branding/favicon

Loss of Power

Discussion in 'Cinestar 8' started by Gary Haynes, Nov 20, 2012.

  1. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    I need some thought from the groups on a loss of power with my CS8.

    Hadn't flown in awhile and flew last Saturday with no problems. 4S Zippy battery, D800 and everything was normal.
    With the 4S throttle was about 60%. Switched to my 5S (Tracos have been replaced on the MK stack) and flew great.

    This morning I went to fly, thought I'd give the 4S another go and almost immediately after liftoff got a low battery warning, voltage dropped below 13 volts within 10 seconds. Tried another battery, QC 4S, same thing. Tried the 5S and flew 6:48 mins and had 52% remaining on charge.

    Flew another 4S and barely got off the ground.

    So this afternoon I took the D800 off, put on my NEX7, checked all the wiring looking for any shorts, found nothing. Powered up with the QC 4S fully charged and got 19 second flight before I dropped to the ground with full throttle (1 foot up and over grass). Tried again and wouldn't even lift off with full throttle. Put the battery on the charger and it was at 85%.

    So I am stumped. Never had anything like this happen. Something seems to be sucking up the power. And I have not changed any configurations or software.

    Here's the voltage/power. You can see the fast decline in the middle.

    FlightTime Voltage Current
    7 14,9 41,2
    8 14,9 44,7
    9 14,6 44,9
    10 14,6 49,8
    11 14,4 49,3
    12 14,7 37,5
    13 13,6 56,5
    14 13,5 46,9
    15 12,7 41,6
    16 11,6 43,7
    17 8,3 46,7
    18 11,2 30,2
    19 14,7 0,5
     

    Attached Files:

  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    I think you posted a CSV version of the GPX file, Gary. Any chance you could post the XML version?

    Thanks
    Andy
     
  3. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Andy it was a raw GPX file. Any other type of spreadsheet file is greyed out when I try to upload it. Suggestions on how to get a excel file in a format that can be uploaded or is it user error?
     
  4. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    If I used an XLSX file, while the forum uploader can see it, I get a message saying it isn't an allowable file type.
     
  5. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Could it be that even though I don't have that many flights on the batteries that they are going bad? They seem to charge correctly and are balanced. How do you tell if a battery has reached end of life? What is the suggested method of storing a battery?
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164

    Hi Gary:

    Understood.

    I can tell from the contents of the file you uploaded that it was not the original file that you copied from the micro-SD card.
    The original files on the micro-SD card are text files (even though they have a file type of .GPX). If you look at them using a text editor, you'll see text lines that look like this:

    <?xml version="1.0" encoding="UTF-8" standalone="no" ?>​
    <gpx creator="NC" version="2.0" >​

    <metadata>​
    <link href="http://www.mikrokopter.de">​
    <text>MikroKopter</text>​
    </link>​
    <desc>FC HW:2.1 SW:0.88e + NC HW:2.0 SW:0.28i</desc>​
    </metadata>​

    <trk>​
    <name>Flight</name>​
    <trkseg>​
    <trkpt lat="+45.5291682" lon="-122.7060843">​
    <ele>0.000</ele>​
    <time>2012-09-02T16:45:54Z</time>​
    <sat>6</sat>​
    <extensions>​
    ...and so on.​

    In contrast the first line or two of the file you uploaded looks like this:
    ;ele;time;sat;Altimeter;Variometer;Course;GroundSpeed;VerticalSpeed;FlightTime;Voltage;Current;Capacity;RCQuality;RCRSSI;Compass;NickAngle;RollAngle;MagnetField;MagnetInclination;MotorCurrent;BL_Temperature;AvaiableMotorPower;FC_I2C_ErrorCounter;AnalogInputs;NCFlag;Servo;WP;FCFlags2;ErrorCode;TargetBearing;TargetDistance;RCSticks;GPSSticks;​
    1;2,652;2012-11-21T01:15:39Z;10;11,' ';3;092;70;27;7;14,9;41,2;83;199;0;071,077;-01;000;110;66,-1;51,37,53,45,45,32,60,34,0,0,0,0;20,20,24,22,16,20,17,19,0,0,0,0;255;000;17,18,20,16;0x81;109,132,0;----,0,0,0;0xc3,0x18;000;000;0;-4,-2,0,-15,0,0,75,3,127,3,109,3;0,0,0,'/';​
    2;2,463;2012-11-21T01:15:40Z;9;8,' ';-2;092;42;-8;8;14,9;44,7;96;209;0;071,060;-01;000;110;66,-1;51,37,53,45,70,46,60,34,0,0,0,0;20,20,24,22,22,24,17,19,0,0,0,0;255;000;14,17,19,22;0x81;109,132,0;----,0,0,0;0xc3,0x18;000;000;0;-1,-3,0,-14,0,0,75,3,127,3,109,3;0,0,0,'/';​

    So I can see that you have processed the original file through, say, Microsoft Excel.

    Might it be possible for you to upload the original file that you got from the micro-SD card, please? I requested the forum administrator to allow the uploading of .GPX files so you should be able to upload exactly as you found it on the micro-SD card.

    Hope this helps...

    Thanks
    Andy.
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    From what you say, given you have not had too many flights on the battery, they seem very "young" to be failing.

    To answer your second question: you should consider storing LiPo's at their "storage voltage." This is typically worked out on a per cell basis -- so the fully-charged voltage is 4.2v per cell, (16.8v for a 4S battery), the completely discharged voltage is 3.0v per cell (12v for a 4s. The mid-point is which, for a 4S will be 14.4volts. If you store them fully charged for more than 24 hours, or discharge them below 12.0v. Thus the typical storage voltage is around 65% of their full charge. So 12 + ((16-12) * 0.65) which is 14.6. A good guide is often to look at the label and you'll see 14.4v which is the "nominal voltage."

    If you leave LiPos fully charged for longer than say "24 hours" then you significantly reduce the ability of the battery to hold a charge. I put "24 hours" in quotes, because I'm not sure I've good science that measures this.

    Also if you discharge the LiPo down below 3.0v per cell, you also significantly reduce the battery's ability to hold a charge.

    Many battery charges have a "Storage" setting that will either discharge a fully charged battery that you didn't get to use or recharge one that you did get to use up to the storage voltage. Even then, if you store them for a long time, I suspect there is a certain amount of self-discharge so it's worthy getting a battery tester so you can measure the voltage.

    This may have happened to these batteries of yours, but only you know their history.

    Hope this helps.
    Andy.
     
  8. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    see if this works. Looks like once a GPX file is opened in GPX viewer it gets changed.
     

    Attached Files:

  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    Thanks. This one's a real GPX file....

    <?xml version="1.0" encoding="UTF-8" standalone="no" ?>​
    <gpx creator="NC" version="2.0" >​

    <metadata>​
    <link href="http://www.mikrokopter.de">​
    <text>MikroKopter</text>​
    </link>​
    <desc>FC HW:2.1 SW:0.88n + NC HW:2.0 SW:0.28n</desc>​
    </metadata>​

    <trk>​
    <name>Flight</name>​
    <trkseg>​
    <trkpt lat="+40.0169306" lon="-105.0447378">​
    <ele>2.342</ele>​
    <time>2012-11-21T01:15:38Z</time>​

    Let me have a look at it for a moment....
    Thanks
    Andy.
     
  10. Howard Dapp

    Howard Dapp Active Member

    Joined:
    Aug 18, 2012
    Messages:
    977
    Likes Received:
    111
    Gary, last year I purchased a load of 4s Turnigy lipos from HobbyKing and at least 3 of them had bad soldering at the leads connected to the actual lipo cell. The problem wasn't easy to track down initially because the lipos would work sometime and other times they would have no power at all. After removing the lipo's plastic wrapping that covers the terminal leads I saw that the + lead was not fully soldered to its terminal. I re-soldered and all was well.

    The photo shows where I had to solder the positive lead to its terminal. This was a brand new lipo!
    turnigy.jpg
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    Hi Gary:
    Some comments:

    1. The battery starts out at 15.3 volts with 43.4 Amp load. To me, that suggests that the battery voltage is sagging under the current load.

    2. As you saw, the voltage just fades away with the low battery FC flag coming on at 8 seconds.

    3. Nothing else I see triggers any alarm bells. The Motor Currents don't look crazy, the BL Temperatures don't look crazy. There are no other warning flags set.

    Without knowing the battery's history, I'd say the battery is shot -- certainly it's exhibiting the traits of an "ex-Lipo battery." You can certainly try charging it up again and see how much charge it will accept (your charger should tell you this).

    Just for comparison, on my most recent flight with a Cinestar/3-Axis/Sony CX760. The initial battery voltage was 16.6v with a current of 34.6 (The C8 was still the ground.) By 10 seconds into the flight, after seven seconds of pulling around 54 Amps, the voltage was at 16.3.
    I was using a QC6200 battery. The low battery first came on briefly after 529 seconds, was on for four seconds, and didn't drop below 14.4 until 588 seconds.

    Hope this helps.
    Andy.
     
  12. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Howard thanks for the tip. But these have all been working fine and I got the same result with my QC6200.

    I checked everything again this evening. Looked through MKtools thinking maybe I lost configuration but it all looks normal.

    Ship flies fine, startup is normal, all of the beeps are normal, initial power up looks and sounds normal, take off to hover and then watch the voltage start to plummet. As the voltage goes down the amps creep up and then there isn't anything left for power.

    And yet I put the battery on the charger and it has plenty of capacity and mah pulled out as shown on the MX20 pretty well match the input on the charge.

    Looking at previous logs I typically pull a total of 40-50amps in flight with the the NEX7. Seeing the same pull in the logs I have checked today.
     
  13. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Andy

    Thanks. I don't think the GPX starts recording immediately. I looked at a few other previous logs and they all start at 4-7 seconds. At power on I had 16.6v on the MX20 at idle pulling about 10amps.

    Looking again at previous logs flying the NEX7 they all start at about the same amps 43-49 or so. Add then the battery slowly goes down. I get the same types of flight time you are seeing.

    Since it is happening with both my QC battery and the other batteries it doesn't seem to be a battery issue. Can't think that they would all go bad at the same time. I'll do some more testing tomorrow and re-fly with the QC 5S that I have.

    I log all of my flights and battery charge data. And flight times/consumption/recharge data is all consistent. The batteries have an average of 55 charge cycles on each with the exception of the QC which is only about 15 cycles.

    Thanks for your review.
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    Gary:
    OK, then this is officially weird. Given you log your battery charge data, that would certainly tend to rule out the battery failure theory.
    Do you have additional QC6200 batteries you could try? The only data we've got left is that your copter doesn't like 4S batteries -- but that doesn't make any sense either -- the amount of power that you'd have to dissipate to produce that rapid voltage drop would cause smoke to come out of the wires.

    The GPX files, according to the code, start as soon as you have a valid GPS fix. The actual source code is in message #12 of this thread. So, if the copter has a GPS fix and the status is "Flying" -- that's when the log file starts.

    Can you tell me where you got the GPX Viewer program from please? I'd like to download it -- and unfortunately "GPX Viewer" produces so many hits from Google I'm not sure which one you're using.

    Using MK_GPX, the log files start at the first second of flight, so I'm curious about your statement that the previous log files start 4-7 seconds into the flight.

    One tentative theory: Perhaps when you first connected up the 5S, might it have had a side effect of upsetting the voltage sensing mechanism so that it no longer reports valid voltages for 4S batteries?

    If you look at the schematic of the FC board (as I just did), you can see there at location A3 (see the reference line of letters across the top and numbers down the side), the main LiPo battery appears on the board as the signal named "SPANNUNG" (German for "voltage.") It feeds into a voltage divider with a capacitor across the grounded side of the divider. The only other place that SPANNUNG goes is to pin 33 of the Atmega CPU (see C1 on the schematic) which is part of the Analog to Digital Converter #4. So that's how the CPU senses the LiPo voltage and can report it back as well as trip the low voltage alarm.

    So my question is this: If you can reproduce this situation of rapid voltage decay, can you actually measure the voltage of the LiPo? Is the FC board really reporting reality or is it reporting an erroneous voltage?

    Hope this helps
    Andy.
     
  15. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Andy

    GPX viewer is on the MK site. They have a couple of different ones. On the site just enter a search for GPX Viewer.

    And it's not just the voltage reporting showing low, it runs out of juice and no amount of throttle will keep it flying. The log I sent earlier was from the first flight. I shutdown, disconnected batt, reconnected and after a normal startup couldn't pull enough power to hover.

    More testing in the morning.
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    OK. Thanks, I'll download that GPX viewer.

    Yeah...your're right -- so the reported battery voltage is correct. So if you're consuming that much power, where's it all going? Or was it not in the battery to start with....

    I'll be interested to hear what you find.

    Andy.
     
  17. Josh Lambeth

    Josh Lambeth Well-Known Member

    Joined:
    Jun 29, 2012
    Messages:
    1,315
    Likes Received:
    216
    Have you checked all your connections? Wondering if you have a loose/cold solder somewhere and it's causing a lot of resistance so it's not being efficient anymore and using more power? Look for some discoloration in the wiring since it would be hot!

    Josh
     
  18. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    So I did two quick flights this morning. I now seem to have a CS8 that generates it's own power. Stripped the ship down to just the frame. Checked all of the wiring and did find a bit of chaffing on the cable that goes from the FC to the GR-16 RX.

    Fully charged battery at beginning. 16.7 volts showing on the MX-20. Immediately on takeoff got a low voltage alarm. GPX log show voltage of 13.6v at 40.6amp draw. Voltagle drifted down to the 13.2 or range within seconds. Stayed there until about 90 seconds then the voltage started to increase. Got as high as 14.0 volts in the log and MX. Then stayed there and I get hovering until I got the alarm again at about 3600mah burned. Total time 5:43. Landed and switched batteries.

    Second flight exactly the same behavior. Warning, keep flying, battery starts increasing and then a total time at about 3600mah burned of 5:59. Flight controls were smooth. Alt and GPS hold were solid.

    GPX shows final voltage 13.4V and 3573mah used. Charge took 3210mah. And looking at other flight logs with charging data this particular battery charging time and capacity is within the same range as previous charges.

    Anyone have a listing of the hex codes for the FCFlags2 data stream?

    Attaching one of the GPX logs.
     
  19. Adam Paugh

    Adam Paugh Distributor

    Joined:
    Jun 29, 2012
    Messages:
    323
    Likes Received:
    78
    Hello Gary,

    When you made the hardware switch to accomodate for 5S did you make the software changes in the MK Tool--Misc for "undervoltage warning"?

    I am curious if a undervoltage warning software setting for a 18.5V lipo will effect the outcome when flying with 4S.

    Greetings,
    Adam
     
  20. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Adam

    Thought about that. i had it coded as a voltage total (13.4) rather than a per cell voltage which I changed last night to 3.4 volts.

    Just did a few more flights. Flew a QC 5S, no problems everything operated perfectly. Pulled out 3300 mah, 6:55 flight time and on the charger now it says I am at 48% so pretty close.

    Tried my QC 4S. Startup showed normal. Took off, within 5 seconds got the warning, took throttle to 100% and it just set down on the ground. Would not take off again, though it did start.

    Switched to a Zippy 4S 8000. Everything normal.

    So it is really beginning to look like batteries going bad. Since this is the first batch I have owned maybe someone can post what the decay and end of life symptoms are for lipos.
     

Share This Page