Has anyone (successfully) installed a backup battery on the APM2s GPS and would be so kind to explain how it works?
Thank you very much.
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Has anyone (successfully) installed a backup battery on the APM2s GPS and would be so kind to explain how it works?
Thank you very much.
You need to be a member of diydrones to add comments!
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Please excuse my ignorance, perhaps I am not seeing the problems you are but wouldn't a simpler / safer solution, what that doesn't include cutting traces and messing with the APM include just powering the APM separately? I use a 68 gram 1200mah 2s battery, and an LM7805 liner regulator / or 5v ubec. Now I can fly all day, swap batteries, and not lose the almanac from resetting the GPS. On a similar note, if my ESC(s) or attached servos are introducing noise into my setup, then I would benefit from powering the APM and the copter separately. I just wanted to throw that possibility out there and get some feed back. What do you think?
Rick
I have installed a plug to separate the battery from APM. But when disconnecting the plug, the saved almanac information is lost. So on the fly field i must first connect USB to get a lock, than plug the backup battery in and than connect the lipo. It is a workaround for now, but not the solution.
I put ferrit coils to the Lipo + line, the UBEC (powering the in rail) and the one ESC ( powering the out rail). No change, no GPS-Lock.
Steven, would you please measure if you have also voltage on the +/- pins of the input rail while backup battery is connected?
Thank you.
The backup battery is feeding 1,4V back into the APM. Maybe a bad solder joint?
The 4-6 sats were outside, blue sky, without backup battery connected, only the APM off the copter, powered by USB. This is really not very good.
This evening I will check if the backup battery is feeding power back into the APM. Maybe the ground pin 3 or 8 must be used for ground. But Steven also used the daughter boards ground pin.
I found something intersting in the data sheet of the MEDIATEK-3329:
The vbackup (Pin4) must be connected for normal operation.
Here is a screenshot
Unfortunately, it is not working anymore. The battery is empty now. It was a brand new one with 3,3V, and now it has only 1,4V. I tested the diode, it is working and connected in the right direction. Any idea?
I also tested GPS accuracy with APM off the copter, connected to PC via USB. Position in MP is walking around in a circle of about 10m while APM is laying on the table with 4-6 sats connected. Is this normal behavior?
I have installed the backup battery with a diode on +.
And IT IS WORKING.
Thank you Jake and Steven.
When disconnecting Lipo for seconds or minutes and than repowering, GPS-Lock is there in 10-20 sec.
But I´m still not so satisfied with it, because I only have 4-6 sats and the accuracy is very poor, about 10-20m. Maybe this is because of the interferences, which prevent the GPS to get lock without the battery. I think I have fought only the symptoms and not the cause.
But I have no idea which part or configuration is emitting the interferences. I have nothing special installed: UBEC (5,22V) on the IN-rail, 6x Hobbywing Skywalker 20A (each min. 2" away from the APM) and one of them connected with +/- on the OUT-rail, all others S and -. No telemetry, and for testing no RX.
Maybe it helps when installing the Diydrones BECs, or/and the original power distrtibution board? Any suggestions?
Thank you very much Steven. This looks quite easy and may help a lot of people, having trouble with GPS lock.
I will try it with a non rechargeable battery, without switch but a diode on the vbat line. Will report as soon as it is working.
Thank you Jake, this may work. But what do you think of the idea to put a switch between the coin cell and the GPS and switch off the connection immediatelly after powering the APM? I think Steven Harsanyi did it this way, posted in this thread.
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