Hi guysRecently A friend Louis and I bought a complete APM 2.5 setup for x8 flying wingsAPM 2.53Dr radio 433 MHzUblox / Mediatek GPSAirspeed sensorAnd the 3DR power module , we completed our setup and started testing the configuration for elevon setup because of the x8 delta wing, then Louis started seeing a problem where after boot up he would try move the servos and APM would reboot.After many hours of testing he asked me to test the same on my setup and since our x8 setups are identical it would be a good test. It turns out when you move servos very slowly APM would work fine but when rolling the elevons around fast on the stick my APM also restarted.We immediately thought of power supply issue and I soldered a 5A BEC to my setup and everything was working 100% that could only mean that our setups was drawing more current then what APM power module could supply . I checked the spec sheet for the 3 DR power module and it states that the module can supply 2.25A !?Then I checked the power consumption today on my setup and stationary I was drawing 900 mah and when motor was running and moving the servos fast it was on average 1300mah , So well under the 2.25 A max limit .Does Anyone have any ideas ?This problem was now confirmed on 3 different setups !
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The really excellent Opto 18 and 30 amp optically isolated ESCs provided with the DJI Flamewheel ARF kits have a great reputation for longevity and do not include BECs.
The Castle Creation 5-10 amp Switching BEC recommended by Jack is superior in every way to the linear BECs found in most ESCs in any case.
A switcher can achieve consistent efficiency in excess of 90 percent.
The linear BECs are lucky to average 50 percent.
On our multicopters it is possible to generally parallel multiple (linear) BECs as found in the ESC's without problem, but they will not produce more peak power than a single BEC the only advantage is that in case of the most common failure one of the other BECs can pick up the load. Unfortunately in the second most common kind of failure the failed BEC can take out one or more of the other ESC's as well. So to cut the extra red wires or not is kind of a crap shoot.
You absolutely cannot parallel switcher BECs however, one to a customer only.
Putting on a sizable capacitor will definitely increase peak short term load capability and will smooth "sag" in any case.
I don't know if the new 3DR power supply is linear or switcher, but if you have a decent size switcher BEC anyway you are probably better off running everything from that.
Two separate power supplies are just 2 separate ways for something to go wrong. Not going to be doing you much good if the APM and receiver are still working and the rest of your plane isn't. - I guess the final flight log!
The manual should be clear on this. The Power Module is only to power APM and its accessories (3DR radio, GPS, RC receiver). It is NOT designed to power your servos. You are supposed to use your ESC as usual for that.
A Power Module that would be able to power any number of servos, including digital ones, would have to be a much larger and more expensive product, and unnecessary for the vast majority of users, who are using standard ESCs with BECs that already provide that function. If there is demand for such a Power Module we could consider making it available as a more expensive option for those who need it.
I met the same failure, with the same configuration, but with 900mhz 3Dr radio. After 2 years of test, 2 apm mega 2560, 2 apm 2.0 and 3 amp 2.5 I can assess that apm is a good low level open project and low cost, but far from a professional (as diy claimed) autopilot system...
Yes i was very disappointed when i had to bypass the apm and fly my X8 with rx only.
I was under the impression that 3DR power module that was included with the apm 2.5+ would make my life easer, power wise. But had to maiden my X8 with no apm. I did not have a Ubec on hand like Johan.
Replies
I hope this in on topic here..
I want to power the input side of my APM 2.5 with 10A bec. I also want to use a 90A Attopilot to monitor current and voltage.
I have it set up very similar to my APM 2.0 and have used the same pins as for APM 2.0, A1 A2 for the voltage current.
I do not get any current readings though. I have set up properly in MP for the Attopilot.
Is there something I am doing wrong?
I have JP1 installed for now, but I expect /plan to remove it and power output rail with a separate BEC.
Am I doing all this right? Maybe my Attopilot is not working?
The really excellent Opto 18 and 30 amp optically isolated ESCs provided with the DJI Flamewheel ARF kits have a great reputation for longevity and do not include BECs.
The Castle Creation 5-10 amp Switching BEC recommended by Jack is superior in every way to the linear BECs found in most ESCs in any case.
A switcher can achieve consistent efficiency in excess of 90 percent.
The linear BECs are lucky to average 50 percent.
On our multicopters it is possible to generally parallel multiple (linear) BECs as found in the ESC's without problem, but they will not produce more peak power than a single BEC the only advantage is that in case of the most common failure one of the other BECs can pick up the load. Unfortunately in the second most common kind of failure the failed BEC can take out one or more of the other ESC's as well. So to cut the extra red wires or not is kind of a crap shoot.
You absolutely cannot parallel switcher BECs however, one to a customer only.
Putting on a sizable capacitor will definitely increase peak short term load capability and will smooth "sag" in any case.
I don't know if the new 3DR power supply is linear or switcher, but if you have a decent size switcher BEC anyway you are probably better off running everything from that.
Two separate power supplies are just 2 separate ways for something to go wrong. Not going to be doing you much good if the APM and receiver are still working and the rest of your plane isn't. - I guess the final flight log!
Yes I still have that tlog(attached)
2013-01-05 19-58-08.tlog
The manual should be clear on this. The Power Module is only to power APM and its accessories (3DR radio, GPS, RC receiver). It is NOT designed to power your servos. You are supposed to use your ESC as usual for that.
A Power Module that would be able to power any number of servos, including digital ones, would have to be a much larger and more expensive product, and unnecessary for the vast majority of users, who are using standard ESCs with BECs that already provide that function. If there is demand for such a Power Module we could consider making it available as a more expensive option for those who need it.
I was under the impression that 3DR power module that was included with the apm 2.5+ would make my life easer, power wise. But had to maiden my X8 with no apm. I did not have a Ubec on hand like Johan.
Very disappointed !!!