"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.…"
"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…"
"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…"
"Vernon, if the solution of the problem is so simple, would you tell us what BEC / UBEC supply clean power? Maybe we can create a list with good parts and bad parts. But I think the solution is unfortunately not so simple."
"Doug, thank you very much for you offered help.
Here is a photo of my PDB and one with the APM over it. Space between them is about 1".
- It´s a DIY-frame.
- APM2 is the soldered version with GPS on the daughter board
- yes I have a voltmeter. The…"
"I have installed the backup battery with a diode on +.
And IT IS WORKING.
Thank you Jake and Steven.
When fist time powering the APM, after some hours without power, than I got GPS-Lock in some minutes. But every time. Before, I got no Lock most…"
"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."
"I have the same issue, even with no RX onboard, only 6 ESCs (Hobbywing Skywalker 20A) each min. 2" away from the APM2. As soon as I connect my ESCs I have no Lock. I am trying and searching for weeks. Some day it is working quite good, but only for…"