Breaker Sizing

[PNLBLDR]

Hi Justin,

Why not run your fuse block off the main vpx lug, and not out of a power pin? Just bypass the VPX entirely for the items on fuses..

[AviatorJ]

Originally Posted by OGee

Looking for comments regarding my IBBS - VPX wiring diagram. Will it work? Is there a better way? Thanks.

https://drive.google.com/file/d/19kc...ew?usp=sharing

I struggled with the want/need to hang the GPS and/or a Comm off the IBBS. In the end I went with the standard TCW drawing showing just the PFD/MFD/ADAHRS/EIS hanging off it, keeping it under the 10 amp fuse size of the battery.

Originally Posted by PNLBLDR

Hi Justin,

Why not run your fuse block off the main vpx lug, and not out of a power pin? Just bypass the VPX entirely for the items on fuses..

Hey Nick. I have a 60 amp ANL between the contactor and the VPX. So my concern would be blowing that out if I hang too much stuff off the power lug. My solution was to basically remove my two USB chargers from the accessory block and bumping it down to 5a. Here's the latest planner-

http://planner.verticalpower.com/printable/share/2722

I am however going to hang some stuff off the input side of the ANL such as the AC compressor, AC evaporator, airhorn and maybe the USB Chargers. I also am going to go ahead and put two shunts in since the harness you guys made already has those leads. Don't want them going to waste, so that will give me a better picture along with the VPX of power being used.

[OGee]

Originally Posted by PNLBLDR

Hi Justin,

Why not run your fuse block off the main vpx lug, and not out of a power pin? Just bypass the VPX entirely for the items on fuses..

Want an on/off avionics switch. By running through the VPX I can configure all avionics (excepting main power for the MFD) to a switch. The power pins for the IBBS will be part of the configuration. Seems I have a bit more flexibility through the VPX.

[OGee]

Running pin 2 (Batt Info) from IBBS to J2 pin 12 (Aux Batt Volt) on the VPX. IBBS says to in stall a 100k Ohm resistor. VPX says to install a 1k Ohm resistor. Has anyone done this? If so, which resistor did you use?

[Carl Froehlich]

Originally Posted by OGee

Want an on/off avionics switch. By running through the VPX I can configure all avionics (excepting main power for the MFD) to a switch. The power pins for the IBBS will be part of the configuration. Seems I have a bit more flexibility through the VPX.

Does this mean you have the VPX and an Avionics Master switch in series? If so, does this translate to two potential single point failure components in series?

I never design in an Avionics Master switch and perhaps I just don?t understand VPX. If so, sorry for my stupid question.

Carl

[OGee]

Originally Posted by Carl Froehlich

Does this mean you have the VPX and an Avionics Master switch in series? If so, does this translate to two potential single point failure components in series?

I never design in an Avionics Master switch and perhaps I just don?t understand VPX. If so, sorry for my stupid question.

Carl

VPX actually does the component switching.

[Carl Froehlich]

Originally Posted by OGee

VPX actually does the component switching.

So if either the physical avionics switch connected to the VPX, or the VPX itself failed you still have avionics?

[AviatorJ]

Originally Posted by Carl Froehlich

So if either the physical avionics switch connected to the VPX, or the VPX itself failed you still have avionics?

Can't speak for 'OldGuy', but in my case I would have to flip the back up battery switch to power my two G3X screens, EIS and ADAHRS... now if all that takes a dive then I have my G5.

[OGee]

Originally Posted by Carl Froehlich

So if either the physical avionics switch connected to the VPX, or the VPX itself failed you still have avionics?

Yes. Here?s the rationale: After engine start I flip the Avionics/IBBS Enable switch (DPDT). I then check the IBBS voltage on the MFD to verify the IBBS is fully charged. Let?s assume the IBBS is fully charged and I am flying. At this point if the IBBS Enable switch has a disconnect it will disable the IBBS. However, the avionics connected to the IBBS continue to function since the IBBS is not the source of power. It is a pass-through portal for the power, the actual source for which is the VPX. Now if the VPX does a Lewinsky the IBBS will sense the voltage drop (under 11 volts) and provide power to the connected devices. So, as I see it the only avenue of failure is to have both the IBBS and the VPX go TU, which i consider highly unlikely?