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Wiring Architecture

rockitdoc

Well Known Member
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I am at the point where I choose between Shunts vs Hall Effect donuts for getting a read on current moving along the alternator 'highway'.

Here's what I have absorbed, to date:

Shunts
proven, old school (that's not a bad thing to me....necessarily)
require 4 connectors at the source
require real estate on the firewall

Hall Effects
are relatively new school
require no connectors at source
use almost no real estate except where they surround a wire

So, Hall Effects doodads seem to be the obvious choice AND this is where I usually find out the error of my reasoning.
 
I have Hall sensors and like them. As you noted, it is very hard to envision a sensor failure that would interrupt the power flow to the panel (we’re talking about a 9 gauge wire routed thru a torus - no connections). I think they are not as accurate as the older style shunts - but I don’t care if it reads 12 amps when it’s really 13.
 
Or none at all. A voltmeter provides much more useful data. How will your decision making change based ammeter readings?

If you really want an ammeter a Hall Effect is better as it is less risky, no potential for sensor wires to become high current although more fore thought is required as the wire has to be routed through the sensor before it is terminated. Hall effect sensors are often sited on the cabin side of the firewall.
 
Or none at all. A voltmeter provides much more useful data. How will your decision making change based ammeter readings?

If you really want an ammeter a Hall Effect is better as it is less risky, no potential for sensor wires to become high current although more fore thought is required as the wire has to be routed through the sensor before it is terminated. Hall effect sensors are often sited on the cabin side of the firewall.

Gonna respectfully disagree, Sir. A Volt Meter is a decent secondary indication of alternator and associated VR health. An amp meter is a decent secondary indication of battery health. Off nominal indications of either parameter should be cause for investigation at a minimum.

With the very wide variety of aircraft systems now available, painting the plethora of electrical requirements with the same brush is a bit hazardous. Adding battery chemistry and the voltage collapse that some exhibit adds to the complexity of sensing pending failure modes. There's been previous debate here.

More specific to the OPs question, I'd probably prefer the HE sensor with the understanding that the characterized reading from any current device is more important than the actual number.
 
I used the shunt because it is a part of the kit was shipped from Dynon and the shunt is a part of the Dynon EMS wiring architecture.

In this case the decision was made for me and it definitely save me from overthinking it.
 
Connections

I originally had a VisionMicrosystem hall effect sensor on my RV-8. It was mounted just behind the firewall on the cockpit side. Absolutely no issues for 17 years. Last year I upgraded to a G3X system and was hoping the VM sensor would be compatible. No such luck. The incompatibility was with the VM sensor. Other HE sensors would have worked fine but installing a new one on a completed airplane would have been a challenge. I therefore firewall mounted the shunt which came with the G3X. Operationally, I see no difference. It is true that the main power line, running through the HE sensor, is not broken. But you still have connections for the sensor wires.
 
I used the shunt because it is a part of the kit was shipped from Dynon and the shunt is a part of the Dynon EMS wiring architecture.

In this case the decision was made for me and it definitely save me from overthinking it.

Same here- My sensor kit for the G3x came with a shunt. I don't even know if I could have opted for a hall effect, but if so, I missed the boat when I ordered stuff. The shunt was no big deal to install. Just a couple of screws through the firewall and a couple of 1 amp inline fuses.

As far as extra failure points, yeah, I get that, but you could say the same about ANL fuses and I put a couple of those in the system. Ultimately I think that shunts have worked in jillions of airplanes and it's not like they are a common failure point, so I'm comfortable with the way I went.
 

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I originally had a VisionMicrosystem hall effect sensor on my RV-8. It was mounted just behind the firewall on the cockpit side. Absolutely no issues for 17 years. Last year I upgraded to a G3X system and was hoping the VM sensor would be compatible. No such luck. The incompatibility was with the VM sensor. Other HE sensors would have worked fine but installing a new one on a completed airplane would have been a challenge. I therefore firewall mounted the shunt which came with the G3X. Operationally, I see no difference. It is true that the main power line, running through the HE sensor, is not broken. But you still have connections for the sensor wires.
Rick
I would prefer to mount my HEs (I’ll have two, one for each alternator) on the cockpit side of firewall but all the big wires from batt to alternators are FWF. That means putting the HE doodads in the cabin also means running those hefty alt wires into cabin. I’m missing something again.
 
Battery Location

My battery is located aft of the baggage compartment so it was easy to install the HE sensor on the cockpit side of the firewall. If my battery were located on the engine side of the firewall, I’d keep the main lines out of the cockpit. That would be my priority over the type of ammeter sensor. I agree with Terry that using a shunt is not a bad decision. But that’s just me.
 
I've never found an ammeter very useful. There are too many options for where to install, alternator output line, battery connection or somewhere else? From my perspective a voltmeter is the primary instrument. Ammeter often drops to a low, and unreliable, reading shortly after engine start. I don't look at it again. The voltmeter is much easier to install and provides useful information about what is supporting the electrical loads, battery or alternator. I would venture that the only reason many install an ammeter is because a shunt is provided with the install kit. My suggestion is leave it in the packaging as it doesn't provide much useful information.
 
I've never found an ammeter very useful. There are too many options for where to install, alternator output line, battery connection or somewhere else? From my perspective a voltmeter is the primary instrument. Ammeter often drops to a low, and unreliable, reading shortly after engine start. I don't look at it again. The voltmeter is much easier to install and provides useful information about what is supporting the electrical loads, battery or alternator. I would venture that the only reason many install an ammeter is because a shunt is provided with the install kit. My suggestion is leave it in the packaging as it doesn't provide much useful information.

I will leave the shunt in the packaging. I'm just at the point of wiring everything, so putting a little Hall Effect doodad on the wires from the alternators is easy and connecting them to the EFIS is also pretty easy. I get your point of a voltmeter and will install that, too. That's probably the gauge of most interest to me during flight scanning of engine health. However, the amp reading coming out of the alternator might be useful if for some reason the amperage was higher than anticipated. Could be a useful way to identify a fault in the loads. Maybe I'm just overthinking this again. Wouldn't be the first time.
 
I will leave the shunt in the packaging. I'm just at the point of wiring everything, so putting a little Hall Effect doodad on the wires from the alternators is easy and connecting them to the EFIS is also pretty easy. I get your point of a voltmeter and will install that, too. That's probably the gauge of most interest to me during flight scanning of engine health. However, the amp reading coming out of the alternator might be useful if for some reason the amperage was higher than anticipated. Could be a useful way to identify a fault in the loads. Maybe I'm just overthinking this again. Wouldn't be the first time.

Have you decided which doodad to buy? I'd be interested in piggybacking off your research. I removed an EI Volt/Amp/shunt gauge, and installing a Hall Effect sensor to the show Amps on the new G3X wouldn't be much work.
 
Colorado RVs

Have you decided which doodad to buy? I'd be interested in piggybacking off your research. I removed an EI Volt/Amp/shunt gauge, and installing a Hall Effect sensor to the show Amps on the new G3X wouldn't be much work.

John
Not to grab Scott's thread, but it looks like you're in Colorado.
I manage a forum of Colorado RV builders and owners.
If you would like to join, shoot me an e-mail (see below)
Name
Cell
City
RV model

Looks like we chewed some of the same dirt. I managed a large Telecom for 15 years. 12,000 lines, 120 facilities.
 
GRT and Amploc

A local builder had a GRT CS-01 fail after ten years. He replaced it with an Amploc Key100, not that there’s anything wrong with choosing the CS-01. Garmin G3X system.

My notes say: The GRT CS01 100A Hall effect sensor has pigtails and is an Amploc KEY100 with a connector shrink-wrapped in place. Sensor ID 0.82”. The Amploc KEY100 has 0.1" spaced pins that look like the headers on PC motherboards. The GRT 50A Hall effect sensor is their CS-02, looks to be smaller ID.

A Skyview EMS Enhanced General Purpose Input will work with these Hall Effect sensors.

BTW you can run two alternator B leads thru one sensor and they will sum.
 
A local builder had a GRT CS-01 fail after ten years. He replaced it with an Amploc Key100, not that there’s anything wrong with choosing the CS-01. Garmin G3X system.

My notes say: The GRT CS01 100A Hall effect sensor has pigtails and is an Amploc KEY100 with a connector shrink-wrapped in place. Sensor ID 0.82”. The Amploc KEY100 has 0.1" spaced pins that look like the headers on PC motherboards. The GRT 50A Hall effect sensor is their CS-02, looks to be smaller ID.

A Skyview EMS Enhanced General Purpose Input will work with these Hall Effect sensors.

BTW you can run two alternator B leads thru one sensor and they will sum.

Ten years is pretty good service IMHO. Do you know how the donut is held in place around the wire?
 
Gonna respectfully disagree, Sir. A Volt Meter is a decent secondary indication of alternator and associated VR health. An amp meter is a decent secondary indication of battery health. Off nominal indications of either parameter should be cause for investigation at a minimum.

With the very wide variety of aircraft systems now available, painting the plethora of electrical requirements with the same brush is a bit hazardous. Adding battery chemistry and the voltage collapse that some exhibit adds to the complexity of sensing pending failure modes. There's been previous debate here.

More specific to the OPs question, I'd probably prefer the HE sensor with the understanding that the characterized reading from any current device is more important than the actual number.

No problem at all with a different opinion expressed - we're all "A Guy" really except for a few folks with established credibility...

From my perspective the voltmeter is the primary indicator of alternator health. If it stays around 14v as I turn on more services then all is good. I don't think there is a reliable indicator of battery health, apart from a capacity check and a second one will often kill a battery. It all depends what the battery has been doing prior to the reading and what load it is currently supporting.
 
No problem at all with a different opinion expressed - we're all "A Guy" really except for a few folks with established credibility...

From my perspective the voltmeter is the primary indicator of alternator health. If it stays around 14v as I turn on more services then all is good. I don't think there is a reliable indicator of battery health, apart from a capacity check and a second one will often kill a battery. It all depends what the battery has been doing prior to the reading and what load it is currently supporting.

While I would agree that Volts are the best primary indication of charging health, I would argue that the are benefits to indicating current draw as well and makes a good secondary indication. Less about charging health and more about the health/condition of the electrical system/components in general.
 
While I would agree that Volts are the best primary indication of charging health, I would argue that the are benefits to indicating current draw as well and makes a good secondary indication. Less about charging health and more about the health/condition of the electrical system/components in general.

This is what I have gathered from the many discussions here. And, the reason I intend having monitoring of voltage and current available in my system. Cuz, why not?
 
@Southern Pete. All good. Secondary Indication -> there is no direct (primary) measurement of the parameter e.g. battery health, alt health.

An alternator can cover up a lot of sins like a bad battery/cell; this example, wattage being converted to unusable heat energy versus making available electrons more useful. If undetected, it will shorten alt life as well. Voltage levels can be very flat over a wide range of alt amp output so knowing bus voltage alone has its limits e,g, one couldn't be aware of a uncharacteristically long, high amp load after start. If could be relatively benign for the ensuing flight; or, it could strand you or cost you some money if the engine won't start away from your home field. There's then the well known extreme case where an aircraft (Lancair IIRC?) with a weak battery(s) got a jump start. No need to debate this decision. Attempted to raise gear after departure, bus voltage collapsed, engine stopped....

Legacy spark and fuel systems are very forgiving. EFI and EI take special design considerations. Lithium x batteries require a different level of understanding of their related behavior. Gotta know the author's mission intentions, systems etc. to make valuable recommendations. That was the intent of my original comment.

Of course, the value of any instrument output only has value if it's understood. Being an engineer, more data -> better so I'm already biased. Compounding this, my selected systems and related electrical architecture require additional consideration. The OPs question regarded current sensor type. Without knowing a lot more about his related systems, missions, etc. no one should be trying to direct related decisions, IMO. Anyway, my 2 cents. Have a good weekend, Sir.
 
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All good. Secondary Indication ->

Of course, the value of any instrument output only has value if it's understood. Being an engineer, more data -> better so I'm already biased. Compounding this, my selected systems and related electrical architecture require additional consideration. The OPs question regarded current sensor type. Without knowing those a lot more about the related systems, missions, etc. no one should be trying to direct that decision, IMO. Anyway, my 2 cents. Have a good weekend, Sir.

So, mission and pertinent equipment:

Day VFR, night VFR, if absolutely necessary
Some local but lots of cross country, some in remote areas of SW
All Dynon
EFIS's: Twin HDX1100's w/battery backups
Primary (60a) and secondary (40a) alternators
Twin Pmags
PC680 Odyssey Extreme

My current thinking is like this:

One main bus for almost everything except cabin lights and stall warning which will come off a battery bus before main contactor.

Failure scenarios:

Main alternator fails - Aux alt covers most everything so I can get to tools
Main contactor fails - Pmags keep ship aloft, EFIS's have batteries and power everything except ADS-B, XPNDR and radio (I have a handheld for this situation), or I could put the COM on the battery bus (have not decided this, yet)

I would appreciate critiques given this mission.

Scott
 
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This might be a bit off topic but a number of folks have touched upon it so I chim here with my 2 cents worth.
I am strongly in favor of displaying both Amp and Volt and I use the amp not only for monitoring my alternator health but my wiring as well.
Let's say you have established a trend for your volt and amp draw for a healthy system which hopefully you have that for your plane.
Now let's consider if:
- your amp is in the normal range and your volt is lower than trend - I am concerned but might not an emergency
- your volt is in the normal range and your amp is higher than it should be - I am concerned and if I can not ascertain the reason, maybe an emergency (Is there a circuit that is drawing excessively, battery is drawing excessively, etc which could end up causing fire)

Only a couple of scenario to show how this can be used as a safety item but it requires knowing your system/plane
 
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This might be a bit off topic but a number of folks have touched upon it so I chim here with my 2 cents worth.
I am strongly in favor of displaying both Amp and Volt and I use the amp not only for monitoring my alternator health but my wiring as well.
Let's say you have established a trend for your volt and amp draw for a healthy system which hopefully you have that for your plane.
Now let's consider if:
- your amp is in the normal range and your volt is lower than trend - I am concerned but might not an emergency
- your volt is in the normal range and your amp is higher than it should be - I am concerned and if I can not ascertain the reason, maybe an emergency (Is there a circuit that is drawing excessively, battery is drawing excessively, etc which could end up causing fire)

Only a couple of scenario to show how this can be used as a safety item but it requires knowing your system/plane
Yes. My plan exactly. I hope I can learn where this info is on my HDX1100.
+1 🤓🤓😎👍
 
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