Depends on type of ammeter and wiring

cbnank said:
I have an RV7-A. Where physically are you installing the ammeter shunt?
Click to expand...
Yea firewall side near BAT is fine, but what kind of ammeter do you have? (LOAD or BAT CHRG/DISCHRG)

Do you have a LOAD METER or CHARGE/DISCHARGE METER? Either way, shunt mounting location is somewhat dictated by your wiring. A better location may be near the the buss on the cockpit side of the firewall to make the wire runs to the gauge shorter and reducing wires penetrating the firewall.

If you are using a LOAD METER (total aircraft electical load monitored all the time the alternator is running) any where on the B-lead is fine. If you B-lead runs all the way to the main buss inside the cockpit, than the SHUNT should can go near the buss, to simplify running the wires to the gauge.

If you are using a BAT CHG/DISCHG METER anywhere on the main feed from the POS side of the BAT to the Buss[/B]. Again if running the BAT FEED to the BUSS, locating the shunt near the buss simplifys (shortens) gauge wiring.

Here are the previous discussions of what is better: Load or Bat Chg/Dischg monitoring. I vote for Load ammeter.
http://www.vansairforce.com/community/showthread.php?t=21786&highlight=shunt
http://www.vansairforce.com/community/showthread.php?t=11177&highlight=shunt
 
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Shunt placement

Sorry, I should have elaborated.

I have a Dynon system and I will be placing the shunt on wire P1 (Van's basic wireing harness) between the buss bar & the copper connector between the master relay & starter relay. I believe Dynon calls it the "A" position.

This would make the position beside the battery a perfect location for the shunt. I was originally thinking about the instrument sub panel, but I think I like the firewall better.

What do some others think?

Thanks
 
Shunt

Bob Nucholls (Aeroelectric Connection) doesn't recommend the 'A' position. This makes it a battery monitor - charge/discharge. If you loose your alternator, this info is useless.....and when the alternator is working, it's almost useless. You should get an idea of how long your battery will last on it's own and land within that time - or have a back-up battery if flying IFR. All of Bob's wiring schematics has the shunt it the 'B' location, functioning as a loadmeter. This also makes it useful if configuring any kind of diagnostics to check/monitor your alternator/regulator health.
 
Scott Hersha said:
Bob Nucholls (Aeroelectric Connection) doesn't recommend the 'A' position. This makes it a battery monitor - charge/discharge. If you loose your alternator, this info is useless.....and when the alternator is working, it's almost useless. You should get an idea of how long your battery will last on it's own and land within that time - or have a back-up battery if flying IFR. All of Bob's wiring schematics has the shunt it the 'B' location, functioning as a loadmeter. This also makes it useful if configuring any kind of diagnostics to check/monitor your alternator/regulator health.
Click to expand...

Happily, I don't always agree with Bob. He does not like "Cessna type" battery/alt switches. I do.
However, I've used his essential buss feed with the diode setup, as well as other ideas.

With a charge/discharge setup, I can easily see the load that different equipment is taking (and if they work), before I start the plane. Once it's running, at a quick glance, it's easy to see that the alternator is doing it's job of handling the load.

If there is an alternator failure, then it's my blinking alt warning light & volt meter, that let's me know exactly what's going on. Needless to say, I prefer "A", which is the same as Van's schematics.

L.Adamson -- RV6A
 
Just as easy...

L. I'm confused...everything you say can be easily seen (easier?) with the loadmeter (Dynon B) set-up...

With a charge/discharge setup, I can easily see the load that different equipment is taking (and if they work), before I start the plane.

OK... switch stuff on... get a negative amps reading.. more stuff, more amps...:)

Once it's running, at a quick glance, it's easy to see that the alternator is doing it's job of handling the load.

OK.. a zero reading in flight says alternator is working... battery charges pretty quickly, but a short positive reading says charging is OK as soon as engine starts...

If there is an alternator failure, then it's my blinking alt warning light & volt meter, that let's me know exactly what's going on. Needless to say, I prefer "A", which is the same as Van's schematics.

Alternator failure in flight is easily seen as a negative reading...

L.Adamson -- RV6A

Seems to me like it is a "different strokes for different folks issue"....:D

Both work equally well with quite clear readings....

gil A
 
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