Hi,
Are there any best practices when using additional BEC to power servos and peripherals? Am I good to go with the attached diagram? I will be powering Flytron strobes with the BEC also, which isn't yet on the picture. They will draw 1A each per flash which is why I'm thinking it's better to use 5A BEC than the 3A ESC that I have.
Replies
Read the wiki here (powering section) where it is well explained:
http://copter.ardupilot.com/wiki/common-pixhawk-overview/#Powering
I did actually read that page and browsed some other examples as well and felt I needed some affirmation to be sure I understood everything - isn't the example diagram basically the same that I have?
I think the way you drew your diagram is making people think you want to power your BEC through your Power Module. I suspect what you mean by "Y Connector" is a splitter after the Power Module, before the main power goes to the ESCs, where you tap off your BEC. That's fine since then the Power Module will also record the Amps used by the BEC.
You will be fine with the setup you are proposing. You can't brownout the Pixhawk the way you have it wired. You might want to consider adding a Zener Diode to the output of your Pixhawk to provide a backup power supply in case your Power Module eats it (Since you are adding a BEC anyway).
Flytron strobes really draw 1 peak Amp each? You might get away using one of your ESCs because of the low duty cycle.
Does this make it any clearer? Sorry for my Paint skills. I think I know what you suspect I mean, but just to be sure... :)
Yes, the specs do say 1 Amp peak. I thought I'd use the BEC just to be sure, since I don't really know how or have the equipment to measure the total power. Later on I will also be adding more electronics, so then I'll be ready for that.
new_and_improved.png
Yep, you're golden with that diagram and it's what I thought you meant. But think about adding a Zener Diode. It's cheap insurance in case something happens in flight to your Power Module. My secret fear is having the multi-wire cable pull out of its connector on the PM. I know, hot glue is my friend.
Here's the link to the Zener stuff. I don't know why 3DR doesn't just go ahead and sell them for a couple of bucks already wired into a servo connector. There are enough stories around of PMs failing.
Is that for the servo power to be independent from a possible power module failure? My logic for powering it through the pwr module is/was that I can measure total amperes consumed.
Hmm.. How does the above method increase the risk of brownouts compared to plugging the BEC directly to battery?