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VPX/PPS and aft battery

JDA_BTR

Well Known Member
Considering doing a VPX-Pro and PPS installation in my new RV8; didn't do it in my RV14 but seems like it could be good.

Aft battery: has anyone done with with a PPS? I suppose the battery cable would run to the VPX and then forward to the PPS rather than out and back? Would require a battery contactor to do that but seems simpler.

Where would the VPX be placed best for an aft battery?
 
I didn’t put my battery in the back and I don’t have a PPS, but I do have a VP-X. I’m thinking the master will be in the back with the battery and a #2 wire run to the PPS on the firewall. Then a power wire back to the VP-X. I used a #6 from the firewall battery master.

I mounted my VP-X behind my GRT sport EFIS displays. I have no idea how to get these pics into the correct orientation.
 

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I've been drawing up the diagram for such a system. Rear battery still has an contactor next to it. From there a wire goes to the PPS first, and from there on via the main bus connector to your VP-X. You master battery switch will ground both the battery contactor and PPS on activation. That's how the manual calls for it. I guess it makes sense to have an single cable going from battery to the PPS for when it draws the large currents for the starter. If you went to VP-X first you would introduce another two crimp and screw connections with potential resistance and voltage drops.

You also would not be able to display the total battery current on your EFIS or panel meter which the PPS measures if you go to the VP-X first. You would only see the starter current. Dunno if that matters.
 
I'm wiring my RV-8 now. Using VP-X Pro, PPS, and aft battery location.

Planning on making the airframe ground on the aft longeron, and running the 2ga positive cable to the PPS via a battery contactor/masterswitch with the contactor mounted to the battery tray.

I'm still thinking about how I'm going route both the battery cable and pitot/AoA tubing down the left side of the fuselage.

As far as mounting the VP-X, I located it under the fwd avionics shelf I created that mounts between the landing gear tower cross brace and the fwd baggage aft bulkhead.

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