VAF Forums

VAF Forums (https://vansairforce.net/community/index.php)
-   Electrical Systems (https://vansairforce.net/community/forumdisplay.php?f=43)
-   -   Are all these on firewalls? Ammeter Shunt, ANL current limited, alternator fuse. (https://vansairforce.net/community/showthread.php?t=191343)

KiloFoxtrot 01-19-2021 04:25 PM

Are all these on firewalls? Ammeter Shunt, ANL current limited, alternator fuse.
 
I am just now at the beginning of FWF work and I'm installing the master and starter relays. I am still learning about electrical / avionics, and will also review more in the Aeroelectric Connection this weekend. My question is probably simple to most of you guys so any quick guidance is welcomed to shorten my learning curve.

Which of these will I need if I am using a B&C alternator 60amp with an external regulator, and the PC680 battery.

Ammeter Shunt, ANL current limited, alternator fuse.

I have seen pictures of firewalls, but don't see consistency when it comes to these parts being installed on firewalls. What other electrical components will I need to allow space for in FWF planning? Is there something else I am missing. Are some guys just installing these parts behind firewall?

RV6_flyer 01-19-2021 04:35 PM

Quote:

Originally Posted by KiloFoxtrot (Post 1495707)
I am just now at the beginning of FWF work and I'm installing the master and starter relays. I am still learning about electrical / avionics, and will also review more in the Aeroelectric Connection this weekend. My question is probably simple to most of you guys so any quick guidance is welcomed to shorten my learning curve.

Which of these will I need if I am using a B&C alternator 60amp with an external regulator, and the PC680 battery.

Ammeter Shunt, ANL current limited, alternator fuse.

I have seen pictures of firewalls, but don't see consistency when it comes to these parts being installed on firewalls. What other electrical components will I need to allow space for in FWF planning? Is there something else I am missing. Are some guys just installing these parts behind firewall?

Location depends on where everything else is.

I would try to have the ammeter shunt in the cockpit if at all possible. There will be TWO (2) wires running to the gauge to tell you current and I like to not have those two wires forward of the firewall.

The Alternator fuse / CB should be the field supply current limiter. I want that in the cockpit so I can take the alternator off line if something goes wrong.

The alternator ANL current limiter is typically on the engine side of the firewall. Again, if it is possible, I would put in in the cockpit to keep it away from the dirty mess that is typically forward of the firewall. IF it requires running the same circuit (wire) through the firewall an extra time, keep it on the dirty side of the firewall.

Carl Froehlich 01-19-2021 04:48 PM

There is no practical need for an ammeter shunt in our modern panel airplanes. Bus voltage alone is a superb indicator of electrical system health. Ammeters are a leftover from when we did not have accurate/economical volt meters.

I did not put an ammeter in any of my three RVs, and never missed it - or having the clunky thing with big wires hanging on the firewall.

Carl

Mich48041 01-19-2021 05:38 PM

A battery contactor and starter contactor need to be on the forward side of the firewall.
An ANL or similar current limiter is needed for the alternator "B" lead, but it can be located either on the
aft or forward side of the firewall depending on where you want the "B" lead to connect to the electrical
system. Like Carl said, a shunt is not needed. If you really want to monitor the current, consider
a hall effect current sensor which will eliminate 4 high current connections.

John Tierney 01-19-2021 05:52 PM

1 Attachment(s)
Here's where I put mine on an RV-7A, based on others examples, and it has worked OK.
The second ANL holder is empty, for a future backup alternator if needed.
I think I got the ANL holders with covers from West Marine.

Bruce 01-19-2021 06:28 PM

Should be on the firewall because of the 6 inch of wire or less.
All with large gauge wire.
You can see this on the schematics .

Boomer

PilotjohnS 01-19-2021 07:51 PM

Just me
 
1 Attachment(s)
For me anything that goes thru the firewall has a anl fuse or fusible links prior to firewall. This is because i want the wires to fry on the firewall side and not introduce smoke in the cockpit.
I am using a shunt to measure battery charge and discharge current. I will know right away if my alternator cant keep the battery charged long before the voltage starts to drop. By the time the voltage drops, it is too late to pick a convienent alternate airport; i would need to get down right away. The current shunt allows me to set the G3x to alarm as soon as the alternator craps out ( a technical term).
Here is picture of my firewall in process of being wired.

Ralph Inkster 01-20-2021 10:29 AM

Don't forget about other systems or controls that are vying for space on the firewall. Plan now where that control cable will be routed, or fuel hose that might end up rubbing against a hot 'B' lead, or battery box mounted where its physically impossible to get a battery in & out.

On my first build, I parked a Cherokee 180 beside my project & used it as a template for doing everything FWF.

bjdecker 01-20-2021 10:37 AM

Quote:

Originally Posted by Carl Froehlich (Post 1495718)
There is no practical need for an ammeter shunt in our modern panel airplanes. Bus voltage alone is a superb indicator of electrical system health. Ammeters are a leftover from when we did not have accurate/economical volt meters.

I did not put an ammeter in any of my three RVs, and never missed it - or having the clunky thing with big wires hanging on the firewall.

Carl

Respectfully - I like having the Ammeter shunt so I can see the state/rate of charge from alternator to battery & rest of bus.

rapid_ascent 01-20-2021 03:16 PM

I have 2 of the current shunts in my system. One for the primary alternator and one for the backup alternator. I want to be able to monitor current output to determine what my load is. My view is by the time you can tell that the voltage is low you are already overloading your system in some way. How much do you need to turn off you don't really know. Or if the current is higher than normal but still in the output range of the alternator you can detect that too.

I may be old school about this but the shunts are not that big and they can be installed right next to the protection fuse so its all pretty easy. I wish they still had ammeters in cars too btw, but that's just me.


All times are GMT -6. The time now is 08:20 AM.