I have a 3 QC6200's that are doing the same... not to that extent but when I was running them in Parellel I was only getting about 7min with a 7D. I could only put 4500mAh back in them and was getting extreme voltage sag. I attributed them to dying early because of the heat here in Phoenix. Are the batteries poofy? Josh
Josh they have always been a little poofy so no more so than normal. And everything looks fine on the wiring. As my previous post from this morning the 5S and my 4S 8000 Turnigy is fine. So will do more testing this afternoon. Leaning towards bad batteries.
Gary: You're correct, by the way -- the Simple GPX Viewer does convert the GPX files that in loads if you say "Save GPX." Also the original GPX files do have a "flight time" value in them so that's where the flight appears to start four seconds or so in. The NC board (which does the flight logging) uses a value from the FC board, FC_STATUS_FLY, which is set after the throttle value exceeds 40 for some period like a second or so -- I need to look at the source code, so that's why there will be those few seconds between power on and "flying," I think. I think the evidence is forcing us both to the same conclusion about LiPo end-of-life. As you say, it would be interesting to hear from others with more extensive experience of "how LiPo's die." Andy.
Gary, If your batterys are swollen in anyway they are done, you will get very short flying times with them .We had very short battery life because we overcharged them over 1c i learnt that the hard way they ballooned up, as soon I would take off i would get the low battery sign even though they where fully charged. This was a expensive learning curve. I had to buy like 30 new batterys!! now I never charge them over 4amps even though I have been told its ok to charge at 8 or 10amps per battery. I have also read that some batterys after 100 cycles say can start loss power from use. I hope this helps Jason
Gary: I checked the Flight Control Board source code. The logic calculates the number of cells based on the initial voltage of the battery. Then it uses either the per cell voltage you entered in MK TOOL, multiplied by the number of cells in the battery, or the total voltage you entered in MK Tool and compares the current voltage to that. Nothing fancier than that. Oh, the maximum battery size the FC board can handle is 6S -- the number 6 is hardwired into the code so it cannot handle anything larger without screwing up the logic for calculating the battery minimum voltage. Andy.
Which brand of batteries were you using, Jason? The QC ones seem to be fine for charging at 2C. Andy.
Understood. The general wisdom on the net seems to be that charging LiPo's slowly is certainly better for them and they will actually absorb more charge too...so charging at 1C is "better" than charging at 2C (unless you're in a hurry). Andy.
If I have the time to wait (and spend in the room keeping an eye on things), I'll charge QC6200's at 1C, otherwise 2C. I have four Hyperion Superduo chargers so I can charge eight at a time. Andy.
Nice set of videos over on Vimeo from Thiago Kraus that he has been posting over the last couple of weeks. Good series on how to start with a new battery, things to look for, etc. Also interesting that he typically charges at only 2-3amps. Not a typo, not 2-3C but really 2-3amps. And has something over 900 flights on one of his first QC6200 batteries. Food for thought... So after some more review I am writing off 4 batteries as D E A D. Thanks for all of the information and comments.
Adam: I looked at the FC board schematics and the input battery voltage goes directly to a pin on the Atmega CPU chip, so it "sees" the real LiPo voltage. That means that you really need to specify the minimum voltage in terms of a per cell voltage in MK Tool rather than total pack voltage -- if you do stick with per cell, all should be ok as the source code adjusts for the total voltage (if I recall correctly). Andy.