Power Module

[Nige8021]

I';ve been looking at the data flash logs and I assume Vcc is the voltage available for the Rx & APM ? 

The info on the APM site http://copter.ardupilot.com/wiki/common-measuring-battery-voltage-and-current-consumption-with-apm/ seems to indicate the power module should be supplying 5.3Volts according to my flash log the Vcc never gets above 4.8~4.9v




None of the ESC';s red wires are connected to the input rail on the FC & the jumper JP1 is removed

[Revs]

The reason for using a 5.3v BEC instead of the usual 5.0v with APM is because there is a slight loss of voltage with the Zener diode.

http://copter.ardupilot.com/wiki/common-autopilots/common-apm25-and-26-overview/#powering_the_apm_2526_board

Positive voltage comes in to a T-junction. to the left is a path through the JP1 to the positive-rail of the Outputs. To the right it flows through an over-voltage, over-current, reverse-polarity protection(500mA fuse and 6V Zener diode). A side effect of passing through the Zener diode is a .37V loss, therefore input voltage should be bumped up by .37V to account for this.

[Nige8021]

I understand why they set it @ 5.3v but if you look at the logs it';s dipping to 4.5v quite often, yet it says " The 3DR Power Module (PM) which is useful because: •it provides a stable 5.3V and 2.25Amp power supply to the APM which reduces the chances of a brown-out "

[Revs]

Exactly which power module are you using? TBH it doesn';t look at stable as mine, which varies between 4.8-4.9v in the logs. Are you able to take a measurement of the PM';s output voltage with it unplugged from the APM?

Also I notice you have a battery failsafe warning so I assume your lipo was low. Do you still get this with a fully charged battery?

[Nige8021]

The PM came with the APM both are clones I assume, the voltage at the connector with it unplugged is 5.27v

The first log the battery voltage started @ 12.6v then dropped to 11v during the flight ( average current 26A) the second log again started @ 12.6v was showing 98% on my checker but just after T/O it dropped to 10.8v and @ 10.4v it initiated battery fail & RTL, The same battery was used in both logs a Flourion 3S 5500Mah 35C but I';m having doubts on this battery as I wouldn';t of expected such a quick voltage drop with 26A

[Paul01]

Flourion batteries are terrible, I have two of them and neither is capable the amps its rated at and both struggle to balance charge as the internal resistance on all the cells varies massively.

[Nige8021]

I did have my suspicions on the flourion as it was so cheap £18 for a 5500 3S 35C, but after a balance charge it came out with a max difference between the cells of 0.012v next time I';ll try two turnigy 2200 30C';s 

[Revs]

I';ve godda agree with Paul here, that is a crazy voltage droop for a battery rated at 192.5A. My 10c (40A) rated batteries have nothing like that kind of v-droop.

Can you post a graph with both the VCC and Voltage displayed, just to see if there';s an coloration between the two. Or even better, upload a log

[Nige8021]

If I put the Vcc & Battery it just shows two virtually flat lines @ just over 10V & just under 5V




These are in the same order as the first two pictures, not sure how to attach a log file?

[Revs]

Yeah dropping below 10v after 90sec is really poor, I';d stop using them in the quad TBH. Save them for some other low-current-draw use or dispose of them.

let us know how you get on with the 2200';s

[Nige8021]

Can';t seem to get the system to allow a log file to be attached ??

[quadfather]

Can';t seem to get the system to allow a log file to be attached ??

If they are text files rename the extension to txt otherwise zip them.

[Nige8021]

Hopefully this will work ?? Why wont it accept .rar  zipped files?

[Nige8021]

Any conclusions from that data log ? other than it';s a dodgy battery?

[pheasant_plucker]

Hopefully this will work ?? Why wont it accept .rar  zipped files?

Because .rar is a compressed container file and the file inside it could be anything. This would open everyone who downloaded it up to the possibility of being hacked.

Gerry

[Nige8021]

Because .rar is a compressed container file and the file inside it could be anything. This would open everyone who downloaded it up to the possibility of being hacked.

Gerry

But a zip file is the same thing isn';t it ?

[pheasant_plucker]

Yes by another name but not quite the same. 

Gerry