I'm building a medium sized drone (wheelbase 600 mm). When I spec'd the motors/props I went for an 8S setup as this appeared better for flight time (thrust per amp looked best for the motor size I was looking for) and keeping the current down seemed to be a good idea at the time....I used Afro HV ESCs (simonK) and a HKpilot for APM 10s capable PDB with the standard power port lead. Everything connected up and worked OK with many connects and disconnects as I progressed through the setup, then an audible POP! (along with the usual crack as the batteries are connected which I have always disliked but can't find a good solution for)The MP2650 switching regulator on my HKPilot PDB failed (the 5V one, the 12V one is still fine). I presume that it pushed all 33.6 volts into my APM2.5 as thats now largely dead too. All the other electronics (GPS, telemetry radio etc survived). My wiring is tidy not bodged so I am positive the build is not at fault.So now I have Pixhawk! And a healthy distrust of MP2650 based 5Volt supplies (most APM power modules are based on this series of regulator, the 4S modules have a lower input voltage version).My batteries are 4S packs in series. Since Pixhawk is protected up to 20V, I am now thinking to use the Attopilot 90A module for voltage current sense, and 2 regulators per pack one 5 and one 12 (from RS components based on the same MP26XX chips I think). I can re wire my Y lead used to connect the packs in series and add thiner leads from the output of each pack to drive the regulators at max 16.8V (or use the balance leads). This way Pixhawk should be protected if the regulators fail as it is protected up to 20V. So two 12V regulators for gimbal and FPV etc and 2 5V regulators for Pixhawk, one through the power port and one through the servo rail (with zenner and cap).I don't like this solution really but It is the bast I can come up with - There are so many "my APM fried and I don't know why posts on here", I suspect (but I don't know) that battery spark could de-stabalise the switching regulator circuit and cause the thing to go unstable and fry. Even if not then input to the regulator if they can fail passing V Supply should be under V Max of the drone electronics (my gimbal and FPV gear should handle 16.8V too).Sorry for the long post. So my question is does anyone have any better ideas / experience or advice? I have read a lot of Pixhawk to +6S posts and stickies but none detail my concerns with the 5V supply design, most just detail the voltage and current measurement.I have also seen a post about the Airbot power board. This looks like a very professional piece of circuitry and uses different regulator chips (2 5V and 1 12V at good current ratings so a very nice solution). Does anyone have experience with this board or know prices? It looks aimed at the professional end of the market - I presume it's expensiveThanks in advanceHenry
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