max electrical power consumption of your system

[KayS]

Hi All,
i am still configuring my electrical system. I will have one EFIS and several gauges that will consume some electrcal power. In addition Dynon AP servos etc. I would say that my system is regarding electrical power consumption somewhere in the middle.
My question to the guys with an ammeter between battery contactor and busses: How much amps does your system draw with all external lights on?
Cheers
Kay

[JonJay]

Hi Kay - I run my shunt as a charge/discharge meter and not as a load meter and don't have my original load calcs handy. However, most run a 60A alternator which provides more than enough power for all your systems. You could go smaller, but the 60A products kind of hit the sweet spot for most RV's.
I am sure others will chime in with a more direct answer if this doesn't move you forward.

[dlloyd3]

Item Amps Day Day App Night Night App
Skyview 2 2 2 2 2
Skyview 2 2 2 2 2
SV Battery 1.5
SV Battery 1.5
AP Servos 2.66 0.2 0.2 0.2 0.2
GMA 240 1 1 1 1 1
GTX 327 2 2 2 2 2
SL30 3.22 3.22 3.22 3.22 3.22
Fuel Pump 3.77 3.77 3.77
Flaps 3.87
Nav Lights 5.27 5.27 5.27
Ldg Lights 12 12
Taxi Lights 12
Strobe Lights 7 7 7 7 7
Int. Lights 0.1 0.1 0.1
Pitot Heat 10
Total 69.89 17.42 21.19 22.79 38.56


Need to update my chart. 50 Amp alternator, so everything turned on would be a no no at almost 70 amps. That is only one of the reasons I no longer fly instrument approaches at night with the pitot heat turned and all lights turned on!

[az_gila]

Here is mine... still provisional at this time though. Since I have selected a VPX unit the Main and Endurance labels don't count.

I wanted drain from the battery, not peak current, so I calculated the Transmitter power at only a 10% duty cycle -

[N941WR]

In flight, with everything on and pushing the PTT, 28 amps is all my plane uses.

Single 10" SkyView w/ ADS-B, Transponder, Autopilot, etc.
A210 radio
Intercom
100W Taxi and Landing lights on
Strobes on
Position lights on
Interior lights on
PocketPanel charging and everything that I can think of running
I can't remember if the flaps were going down or not. Oh well, time for another test flight.

[KayS]

thanks for the answers. I do have an standard plane power 60A alt. For instance one thing I am wondering about is if my 30A ammeter shunt (i don't recall why I didn't buy the 60A version years ago) is sufficient enough to withstand the load of the system. I am not an expert on shunts but i think an "overloaded" shunt could create some problems.

@Dave/Gil: wow, these are pretty high figures.

[az_gila]

Originally Posted by KayS

thanks for the answers. I do have an standard plane power 60A alt. For instance one thing I am wondering about is if my 30A ammeter shunt (i don't recall why I didn't buy the 60A version years ago) is sufficient enough to withstand the load of the system. I am not an expert on shunts but i think an "overloaded" shunt could create some problems.

@Dave/Gil: wow, these are pretty high figures.

Yes.. get the 60 Amp shunt...

I updated my load analysis to show what happens if you shed loads in an electrical emergency and use the EFIS built-in batteries.



You should be able to fly to a safe location using the Dynon maps and a minimum electrical load of 2.7 Amps. Add 3 Amps for Autopilot if needed and try and not to use the 7.3 Amps of Pitot Heat

[N941WR]

Today, while doing some test flying, I turned everything on in flight, slowed down and pressed the PTT while deploying the flaps under load.

My ammeter went up to 28 amps total. My original post understated my number but was what I typically saw in flight.

Those 100 watt landing and taxi lights really bumped up my current draw.

I agree, design it for 60 amps. You have no idea today, what you might add tomorrow. On the good side, the power requirements of modern electronics is dropping, so you will probably never need all 60 amps.