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Lost electric over mountains at night

I'm a new RV-7A owner and last night was 'unique' to say the least.

I had my plane in for standard ADS-B install at an avionics shop. I have owned the a/c for about a week and a half with 3 or 4 flights and a bunch of daytime T&Gs under my belt and I'm comfortable with the with the plane (it is very easy to fly, land and very tame IMHO). Plane is beautiful: professionally built, low time all glass electric panel with backup steam gauges. The GRT screens are still befuddling to me and I feel like a dog watching TV (coming out of a G1000 panel). I'm still learning GRT buttonology in other words.

The install went way too long (forcing me to leave at sunset!); however it was only a short (40' flight) so what could go wrong? Well.. when I went to start up, the battery was drained (avionics were on/off all day long), so the shop gave me a boost to get the engine going. I launched with a bit of dread: I was going to fly over some serious terrain and one very tall pass at night in an unfamiliar airplane coming out the shop with a weak battery. What could go wrong indeed?

Oh about 15' later, as darkness surrounded me, and approaching the pass (I was at 14,000'), I turned on the Nav lights, pitot heat and everything just went dead instantly. No efis panels, GPS 400w or inside lights. A/C has e-mags BTW. On a positive note, I have lots of mountain flight time and am very familiar with the local terrain. This is important!

The steam gauges and a tru-trak electric ADI plus an iPAD for terrain and course were working so I was okay. I used my iPhone to light up airspeed and altimeter and luckily I got cell service. I called my destination airport (airport mgr) and screaming into the iphone (no headset or bluetooth for the bose) asked him to activate PCL so I would have lights. I thought I heard him say OKAY, so that was reassuring. I was only about 30' from destination and had runway lights but no landing lights. I did a perfect no-flap landing with a pretty gusty cross wind (12g20). This is a capable airplane in an emergency; however my decision making sucked I realize, so please don't flame me. I should have left the plane there got a rental car and made the 2+ hour car ride home. Sheesh! I consider myself a seasoned and safe pilot but got complacent and nearly had a bad outcome. I think my alternator took a dump but must investigate further. Lesson to all.
 
"This is a capable airplane in an emergency; however my decision making sucked I realize, so please don't flame me. I should have left the plane there got a rental car and made the 2+ hour car ride home. Sheesh! I consider myself a seasoned and safe pilot but got complacent and nearly had a bad outcome. I think my alternator took a dump but must investigate further. Lesson to all".

Nothing more to add. I'm familiar with the terrain and would not feel comfortable even with all doodads running at night.
__________________
 
Losing power is sucks, glad it all ended well. I would check your diodes. I lost power a couple times, replaced alt did not help. Took some time but finally found a diode that was bad as well as a master switch. no problem since.
 
Steam AND Glass?????

So you had steam gauges and glass and the electrons went tangle uniform?
Imagine that. Your risk mitigation plan of having both steam and glass was a smart decision. You have now joined the club of those who have had electronic failure with steam backup. Glad you were able to write this report rather than us read about it from the NTSB.

The glass only crowd would be wise to take notice.
 
glad you made it. that was stacked up on the risk side. thx for posting. I've needed to use steam gauges when everything goes black. in my case at 20K+ and sleepy, I turned my avionics master off I could not understand to turn it back on, but I could read the steam gauges.
 
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It really doesn't sound like just an alternator failure. Usually an alternator failure will be followed by a slow brown-out as you deplete the battery. And your grt should be flashing a warning if the alternator has failed. I can’t help but note that if you had turned on the nav lights prior to departure (you said it was sunset) and left the pitot heat alone (was there any moisture visible?) you may never have known about this issue, so maybe it’s a blessing in disguise. Just a general comment: imho there are a surprisingly significant number of pilots flying sophisticated avionics, who don’t really understand them well enough to use them to their full capability. Again, my opinion: for every hour of flight checkout, most pilots new to an RV need two hours on the ground, with the systems. Finally, thanks for the reminder: ‘get-home-itis’ can be an illness we all need to guard against.
 
Depleted Battery

I'm a new RV-7A owner and last night was 'unique' to say the least.

I had my plane in for standard ADS-B install at an avionics shop. I have owned the a/c for about a week and a half with 3 or 4 flights and a bunch of daytime T&Gs under my belt and I'm comfortable with the with the plane (it is very easy to fly, land and very tame IMHO). Plane is beautiful: professionally built, low time all glass electric panel with backup steam gauges. The GRT screens are still befuddling to me and I feel like a dog watching TV (coming out of a G1000 panel). I'm still learning GRT buttonology in other words.

The install went way too long (forcing me to leave at sunset!); however it was only a short (40' flight) so what could go wrong? Well.. when I went to start up, the battery was drained (avionics were on/off all day long), so the shop gave me a boost to get the engine going. I launched with a bit of dread: I was going to fly over some serious terrain and one very tall pass at night in an unfamiliar airplane coming out the shop with a weak battery. What could go wrong indeed?

Oh about 15' later, as darkness surrounded me, and approaching the pass (I was at 14,000'), I turned on the Nav lights, pitot heat and everything just went dead instantly. No efis panels, GPS 400w or inside lights. A/C has e-mags BTW. On a positive note, I have lots of mountain flight time and am very familiar with the local terrain. This is important!

The steam gauges and a tru-trak electric ADI plus an iPAD for terrain and course were working so I was okay. I used my iPhone to light up airspeed and altimeter and luckily I got cell service. I called my destination airport (airport mgr) and screaming into the iphone (no headset or bluetooth for the bose) asked him to activate PCL so I would have lights. I thought I heard him say OKAY, so that was reassuring. I was only about 30' from destination and had runway lights but no landing lights. I did a perfect no-flap landing with a pretty gusty cross wind (12g20). This is a capable airplane in an emergency; however my decision making sucked I realize, so please don't flame me. I should have left the plane there got a rental car and made the 2+ hour car ride home. Sheesh! I consider myself a seasoned and safe pilot but got complacent and nearly had a bad outcome. I think my alternator took a dump but must investigate further. Lesson to all.

So several comments:

1. Launching an electrical dependent panel or plane or for a night flight immediately after jump-starting a dead battery is frequently going to be a recipe for disaster, as I think you already know.

2. Instead of renting a car and driving home or flying, why not leave the plane on a slow-charger overnight and seek local lodging, then depart the next morning?

3. Time to get more familiar with your aircraft’s electrical architecture and understand all failure modes and backup options.

Skylor
 
Welcome to VAF!

I'm a new RV-7A owner and last night was 'unique' to say the least.

I had my plane in for standard ADS-B install at an avionics shop. I have owned the a/c for about a week and a half with 3 or 4 flights and a bunch of daytime T&Gs under my belt and I'm comfortable with the with the plane (it is very easy to fly, land and very tame IMHO). Plane is beautiful: professionally built, low time all glass electric panel with backup steam gauges. The GRT screens are still befuddling to me and I feel like a dog watching TV (coming out of a G1000 panel). I'm still learning GRT buttonology in other words.

The install went way too long (forcing me to leave at sunset!); however it was only a short (40' flight) so what could go wrong? Well.. when I went to start up, the battery was drained (avionics were on/off all day long), so the shop gave me a boost to get the engine going. I launched with a bit of dread: I was going to fly over some serious terrain and one very tall pass at night in an unfamiliar airplane coming out the shop with a weak battery. What could go wrong indeed?

Oh about 15' later, as darkness surrounded me, and approaching the pass (I was at 14,000'), I turned on the Nav lights, pitot heat and everything just went dead instantly. No efis panels, GPS 400w or inside lights. A/C has e-mags BTW. On a positive note, I have lots of mountain flight time and am very familiar with the local terrain. This is important!

The steam gauges and a tru-trak electric ADI plus an iPAD for terrain and course were working so I was okay. I used my iPhone to light up airspeed and altimeter and luckily I got cell service. I called my destination airport (airport mgr) and screaming into the iphone (no headset or bluetooth for the bose) asked him to activate PCL so I would have lights. I thought I heard him say OKAY, so that was reassuring. I was only about 30' from destination and had runway lights but no landing lights. I did a perfect no-flap landing with a pretty gusty cross wind (12g20). This is a capable airplane in an emergency; however my decision making sucked I realize, so please don't flame me. I should have left the plane there got a rental car and made the 2+ hour car ride home. Sheesh! I consider myself a seasoned and safe pilot but got complacent and nearly had a bad outcome. I think my alternator took a dump but must investigate further. Lesson to all.
Welcome to VAF Mark and thanks for sharing this experience! I think we can all learn from this reminder. You might contact AOPA Safety - they have a good podcast where they discuss these kinds of things, and help deconstruct it to help other pilots learn how they can avoid a similar situation.
 
Mark-

Glad you made it safely. Which direction were you coming from? Over the Arkansas valley the terrain isn't bad, but getting there mostly means crossing a lot of rocks. I have yet to do it at night, and I'm not sure I'd be comfortable (at minimum, I am sure the engine would make all kinds of suspicious noises!)

Incidentally, are you in the blue hangars? I think my brother sent me a pic of your 7A in the open hangar Thursday morning while he was putting the snowmobiles back in the hangar. I'll stop in and say hi next time I am in town.

Thomas
 
Can you post what you find the problem to be? Did you have a backup battery for the GRT’s and if so did that fail also?
 
Mark-

Glad you made it safely. Which direction were you coming from? Over the Arkansas valley the terrain isn't bad, but getting there mostly means crossing a lot of rocks. I have yet to do it at night, and I'm not sure I'd be comfortable (at minimum, I am sure the engine would make all kinds of suspicious noises!)

Incidentally, are you in the blue hangars? I think my brother sent me a pic of your 7A in the open hangar Thursday morning while he was putting the snowmobiles back in the hangar. I'll stop in and say hi next time I am in town.

Thomas

Hi Thomas,
I own two blue box hangars and I'm normally around in my office in Hangar B (east most hangar...man door on east side). I was coming from Alamosa and had to go over Poncha pass. Following car lights on 285 at night was helpful! I kept thinking of the old adage: "better to be on the ground wishing I was in the air rather than vice versa". Stop by any time!
Mark
 
So you had steam gauges and glass and the electrons went tangle uniform?
Imagine that. Your risk mitigation plan of having both steam and glass was a smart decision. You have now joined the club of those who have had electronic failure with steam backup. Glad you were able to write this report rather than us read about it from the NTSB.

The glass only crowd would be wise to take notice.

Seems to me a single G5 with it's built-in battery and GPS (and dissimilar hardware and software) is a more than capable, reliable and redundant backup to my G3X panel (that also has an IBBS for backup power). Hard to match that with any number of steam gauges.

I'm perfectly comfortable with a glass-only panel.
 
A lot of us have a backup alternator on the vacuum pad too. I don't use my G5 but the battery is there as a failsafe. Some headsets will do bluetooth with the phone. I probably do want to get a set of aviation plugs for my handheld....
 
Can you post what you find the problem to be? Did you have a backup battery for the GRT’s and if so did that fail also?

I'll let you know what I find.... BTW can you get battery backups for GRT screens? I have four of these little suckers but only need one battery for one screen. Here is my panel... powered on battery bus only... you can see my voltage is only 11.7v. Note that the GRT only gives a voltage readout. There is no readout for alternator output (perhaps not configured). This seems odd but does anybody have a suggestion as to why this is not being displayed? I would have immediately noticed an alternator defect (not charging) prior to my flight! Instead, I only saw a low voltage error which I attributed to a dead battery. Little knowledge is dangerous (duh).

IMG_0414.jpg
 
Your ammeter shunt IMO should be installed on the alternator feed so that you can see the current supplied to the system by said alternator. If it is 0 or too low -> alternator failure. I have a second ammeter on the line from the master into the cabin so I can compare use to supply; handy in checking load currents on battery on the ground but not so useful most of the time.

TCW sells an avionics backup battery you can look into.

A backup alternator might be your wisest investment.

Any chance you didn't turn your alternator on? You probably start with it off and turn it on after start by checklist? Does that switch work? Your instrumentation doesn't seem to have any way to check any of that.
 
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Instead, I only saw a low voltage error which I attributed to a dead battery. Little knowledge is dangerous (duh).

View attachment 6175

a voltmeter is fine for determining alternator health. A charged battery will read 12.8 volts or around 13.0-13.2 immediately after engine shut down. Once the engine is running with a healthy alternator, your voltage should read 13.8-14.4 volts, even if your battery was discharged. If your voltage is below about 13.4, you can assume that your alternator is not providing any output. NEVER take off with voltage below 13.5! Add this to your checklist.
 
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Mark,

Welcome to the RV world - and glad you flight ended well.

Some thoughts:
- As has been pointing out, recommend you never “jump” your battery and then launch into the ether. If you drain you battery then charge it fully before flight. For that matter having a connection for a regulated power supply to run stuff on the ground is, in my opinion, required. Note - a regulated power supply, never run your panel with a battery charger connected.
- Any battery that has been depleted as you describe should be considered degraded, as in not airworthy. You may be able to breath some life into it, but battery capacity is now unknown. Replace the battery.
- There are many RV builders around that can install any ADS-B system. Here is example of why I caution people about using “professionals” to do avionics work. I’ve had to fix a few of these professional installs on other experimental. Add to that you now have no clue what they did (as far as wire runs and connections). I suggest the next time you want to do an avionics mod you find an RV builder and try doing it yourself.
- Let us know if this was and alternator issue or not. Loss of an alternator is the most probable risk, but not the one that presents an unmanageable outcome - assuming you launch with an all up battery.

Carl
 
Mark,

Welcome to the RV world - and glad you flight ended well.

Some thoughts:
- As has been pointing out, recommend you never “jump” your battery and then launch into the ether. If you drain you battery then charge it fully before flight. For that matter having a connection for a regulated power supply to run stuff on the ground is, in my opinion, required. Note - a regulated power supply, never run your panel with a battery charger connected.
- Any battery that has been depleted as you describe should be considered degraded, as in not airworthy. You may be able to breath some life into it, but battery capacity is now unknown. Replace the battery.
- There are many RV builders around that can install any ADS-B system. Here is example of why I caution people about using “professionals” to do avionics work. I’ve had to fix a few of these professional installs on other experimental. Add to that you now have no clue what they did (as far as wire runs and connections). I suggest the next time you want to do an avionics mod you find an RV builder and try doing it yourself.
- Let us know if this was and alternator issue or not. Loss of an alternator is the most probable risk, but not the one that presents an unmanageable outcome - assuming you launch with an all up battery.

Carl

Thank you Carl... a new battery is first on my list of to do. Its small-ish AGM. Do folks use Lithiums? Just wondering.
 
Thank you Carl... a new battery is first on my list of to do. Its small-ish AGM. Do folks use Lithiums? Just wondering.

Mark,

EarthX is the lithium battery most use. I suggest however that for now, you just replace what you have with the equivalent Odyssey battery. After that spend some time reviewing the abundance of VAF posts on people using this battery.

As you gain knowledge on your plane you will be in a better position to decide which way to go.

Carl
 
Jump started battery and B-lead protection

Jump starting a dead battery will load the alternator pretty hard. The battery is saying "Gimme, gimme, gimme". The alternator will try and match the demand and will make more than rated amps. This will tend to overheat the alternator. Diodes are devices that do not like heat, for sure. Depending on how the B-lead is protected, when you up the load by turning on all the big guns such as pitot heat and lights, it might just blow a breaker. All the old Cessnas route the B-lead to a breaker on the panel that is rated at nominal alternator output. This is bound to pop in such an overload scenario. It happened to me one time when I already had my hands full with a partial engine power failure. A much better setup is an ANL current limiter on the firewall. Those will happily carry much more than rated load almost indefinitely, yet blow when shorted. I know that some RVs have been built with Cessna style B-lead breakers. That might be what happened to the OP. Once the alternator is offline and the battery is already dead... well things get dark right now.

Remember - we need to protect the alternator from the battery, not vice-versa.

Ed Holyoke
 
With respect to the OP's question about battery backup for the GRT screens, the answer is an unequivocal YES!

GRT has provided each EFIS with three separate diode-isolated power inputs, power 1, power 2 and power 3. Normally power 1 is normal aircraft 12V from a fuse or circuit breaker on the main bus. Power 2 can be wired to any source of 12V.

In our aircraft I installed a simple 9ah server backup battery; it's small, cheap and readily available, plus it comes with 14" Fast-on terminals so it's easy to wire. This is what I call the Essential Bus Battery.

The Essential Buss Battery (EBB) gets its charge from a circuit breaker on the main bus through a low-loss Schottky diode. The EBB then powers the Essential Bus through a simple on-off switch (appropriately rated for the application). A circuit breaker for each GRT EFIS is located on the Essential Bus and power from each of these CB's is fed to Power 2 input on each EFIS and the primary power input on the EIS.

When wired in this manner their is very little pilot action required to make things work. Hop in the airplane, flip on the Essential Bus switch... the EFIS boxes and the EIS come alive. Go through your normal start routine - as soon as the Master switch is turned on the GRT gear is getting its power from the main bus via Power 1 input. Hit the start button and the main bus voltage might sag as a result of the starter current. No problem - the GRT gear has stable power available on Power 2 input so they don't even blink during the start. Once the engine is running in a stable fashion the alternator is recharging the Essential Bus Battery and the GRT gear is taking its power from the main bus on the Power 1 input.

Now when things get gnarly and the main bus poops out, the poor pilot doesn't have to do a thing but keep on flying. The GRT gear auto-magically takes its power from whichever power input has the higher voltage. Since the main bus has gone kaput, the Essential Bus has the higher voltage to the GRT gear takes its power from the Essential Bus Battery.

This really is a simple system and very worthwhile to have in the aircraft, especially as you've discovered the hard way!
 
The suddenness of the event needs to be explored. It did not sound like some of the alternator or battery issues we've read about on VAF.

Dave
 
Others have pretty well covered your questions.
Yes, you should set your GRT to alarm if buss voltage is less than 13.8 or so. Alternator is not working.
Yes, the GRT can display alternator output current. It uses a Hall effect sensor that they sell. Look for a green colored ring about 2” in diameter, with the heavy duty alternator output wire going thru it. Or perhaps the builder did not install it.
Others have described secondary power inputs for the efis. Or you may have a backup mini-efis with its own battery?
 
Mark,

We all make “mistakes” and if we’re lucky survive to add them to our bag of “experience.” Once you’ve discovered what caused you power failure and have addressed the issue, I strongly recommend you take some serious time to better learn your panel and EFIS system. Of course the best place to accomplish this is sitting on the ground with the engine off, few distractions, manuals in hand along with viewing a few UTube videos. GRT has some excellent videos on its website that will help.

As you’ve discovered understanding “buttonology” is an important skill and unfortunately takes time and practice - especially with the GRT EFIS system and it’s exceptional capabilities. Aircraft batteries don’t like this so I recommend you “invest” in a cheap external power supply.

I purchased mine on Amazon - a 110v to 12v, 25amp power supply for under $40 along with a power cord and wired alligator clips. I use it quite often to power up my avionics (EFIS, autopilot and Garmin 430s) for just this “learning purpose.”

I connect the external power supply (positive lead) to my panel’s main 70 amp circuit breaker (negative lead to aircraft ground terminal) using the alligator clip wires. This powers the panel without having to turn the battery on allowing me all the time I want to practice GRT and Trutrac Autopilot “buttonology” and improve my 430 data entry skills.

IMHO, having and using an external power supply to learn and practice your buttonology is critical to flying a safe IFR EFIS equipped aircraft.
 
Glad the outcome was a good one and a learning experience for you and all of us. That is one of the purposes of this group: learn from the mistakes of others; you don't have time to make them all yourself...! Yeah, time to stare at those glass screens for a while in a quiet hangar....

I've been over The Rocks to your airport. Can be an interesting ride even on a good day. Mountain flying is a different breed of animal, even in our capable aircraft. And in the dark (inside AND out)? Yikes! Are there ever anything but crosswinds at KAEJ?

Happy Holidays, All.....

Michael
1946 J-3 Cub (since I was 21...!) Batteries. Huh. I've heard of those......:D:D
1997 RV-4 SN 2860 (slow-built)
 

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Electronics: DYI as opposed to a "shop".

These are pictures from a previous thread from an RV-10 that was "professionally" wired at a shop. I agree that asking around and having someone help you who has done their own RV can be a much better option.....
 

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Your battery was fully discharged but may be okay. Depending on the vendor there are battery conditioners that can bring it up to speed without getting a new one. Even if you get a new one make sure you have the charger that the battery specs call out as okay - it does matter.

I also disagree that bus voltage is an acceptable way to monitor alternator function. Seeing alternator current with an ammeter is tried and true. It is cheap and easy too. Most planes I have flown had some form of alternator failure light and/or an ammeter. Most didn't have a voltage readout.

The thought about the fuse-link blowing when you turned on a lot of load on low battery - possible. Most of them can take a lot of current though (60-80A). I wonder if you have a fuse-link when you don't have a shunt? Most people have the two together.

What is the switch "ADI Emergency Power" in the upper right of your panel?
What is the "Engine" light for?
 
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One thing I notice in the panel photo: no GRT EIS. It’s possible that it’s remote mounted, but without it you won’t have 4 cylinder EGT info. I can’t recall if it’s also needed for alternator current. I also see the GRT efis units appear to be first generation - I’m not sure what they can/cannot do.
 
"Well.. when I went to start up, the battery was drained (avionics were on/off all day long), so the shop gave me a boost to get the engine going. I launched with a bit of dread: I was going to fly over some serious terrain and one very tall pass at night in an unfamiliar airplane coming out the shop with a weak battery. What could go wrong indeed?"

A couple weeks ago road junkie posted "If you think it may not be a good idea, it probably isn't."

As others have posted in different words, it is risky for a few reasons to charge a battery (from almost totally drained) with the alternator. I am sure most of us have done it at some time.
 
Instruments

Many years ago a Jet Commander departed Burlington VT and disappeared into Lake Champlain. The airplane was never recovered. This and other similar incidents resulted in a requirement for a battery powered attitude gyro for all US registered Jets.
On a King Air Medivac flight the pilot failed to turn on the generators. Everything electric went away in IMC conditions. They broke out in a hole, circled down and landed in a farm field. Pretty much trashed the airplane but no injuries.
Almost forgot, one engine quit before landing the tanks were empty. Another medivac King Air sitting at the end of the runway for takeoff. the pilot was programming his hand held GPS. The medic in the front cabin seat noted the lights getting dim and told the pilot "you might want to turn the generators on".
Fortunately they had enough voltage to energize the generators.
It is likely that in the OP incident there was not enough voltage to energize the alternator. In that event all that is needed is to charge the battery.
If the battery will not crank the engine I charge the battery before takeoff.
 
If the battery will not crank the engine I charge the battery before takeoff.

I hope you don't mind if I slightly edit your good idea:

If the battery will not crank the engine I FULLY charge the battery before takeoff.

Then I make certain that the alternator is really working before takeoff, as well.
 
Not sure about the primacy of amperage monitoring.

I'll throw this out as a dissenting opinion, for whatever discussion value it may offer.

I have recently developed an erratic alternator output shunt amperage indication on my glass panel as well as an apparently failed red cube. During these intermittent amperage reading outages, the voltage from the two alternators has remained steady at their respective set points (they are in cascade with the main at 14.3 and the backup at 13.6 if memory serves).

Bottom line on top - I never pay attention to the amperage reading except when the EFIS lady admonishes me to "Check amperage!" At that point I note that the shunt reading is fluctuating, sometimes negative, and therefore not reliable. A simple glance at the voltage holding steady in the 14's on the main alternator (and the 13's on the backup) under a 20+ amp load from the avionics and lights is all it takes to assure me the fault is in the shunt wiring and not the aircraft charging system. Therefore, the shunt is coming out as an unneeded accessory, and will be donating its wires (potted firmly in the firewall pass-through) to the replacement red cube in its new FWF location so that I don't have to drill a new hole and mount a new pass-though just for it.

The only reason I installed a shunt is that it came in the Dynon engine instrumentation package deal. It's coming out of my airplane because it's become unreliable, I need the wiring for other purposes, and I'm convinced that bus voltage tells me all I need to know about my alternators' performance.

Just my $.02
 
I'll throw this out as a dissenting opinion, for whatever discussion value it may offer.

I have recently developed an erratic alternator output shunt amperage indication on my glass panel as well as an apparently failed red cube. During these intermittent amperage reading outages, the voltage from the two alternators has remained steady at their respective set points (they are in cascade with the main at 14.3 and the backup at 13.6 if memory serves).

Bottom line on top - I never pay attention to the amperage reading except when the EFIS lady admonishes me to "Check amperage!" At that point I note that the shunt reading is fluctuating, sometimes negative, and therefore not reliable. A simple glance at the voltage holding steady in the 14's on the main alternator (and the 13's on the backup) under a 20+ amp load from the avionics and lights is all it takes to assure me the fault is in the shunt wiring and not the aircraft charging system. Therefore, the shunt is coming out as an unneeded accessory, and will be donating its wires (potted firmly in the firewall pass-through) to the replacement red cube in its new FWF location so that I don't have to drill a new hole and mount a new pass-though just for it.

The only reason I installed a shunt is that it came in the Dynon engine instrumentation package deal. It's coming out of my airplane because it's become unreliable, I need the wiring for other purposes, and I'm convinced that bus voltage tells me all I need to know about my alternators' performance.

Just my $.02

I agree completely that voltage is the only parameter needed for the alternator health so I only measure amps for current draw of the buss, not charging amps. The ammeter is for power management in case of an alternator failure. Sure, there is a emergency card with lots of instructions, but just using heads-up observation of the ammeter can get me to minimum if needed. Then the voltmeter becomes a battery reserve indicator.
 
One more input:

As far as I can discern, the AGM batteries need to charge at 14.7volts. This is quite a bit higher than a std battery would use - and most regulators are set for this type of battery; thus your expensive Odyssey could die rather quickly. Check the Odyssey site to see what their recommended chargers put out - they know what should be going into the battery. I tweaked my B&C regulator as soon as I saw what the battery actually needed. I recommend you do the same thing.

I do not know how to tweak an alternator (internally regulated) to put out the correct voltage for the AGM batteries. Could this be the cause of the early death of some Odyssey batteries?

For all I know, the lithium batteries might need some other specific charging voltage? Best to know what is needed if you have one of these batteries if you want a full charge from your alternator.
 
As far as I can discern, the AGM batteries need to charge at 14.7volts. This is quite a bit higher than a std battery would use - and most regulators are set for this type of battery; thus your expensive Odyssey could die rather quickly. Check the Odyssey site to see what their recommended chargers put out - they know what should be going into the battery. I tweaked my B&C regulator as soon as I saw what the battery actually needed. I recommend you do the same thing.

I do not know how to tweak an alternator (internally regulated) to put out the correct voltage for the AGM batteries. Could this be the cause of the early death of some Odyssey batteries?

For all I know, the lithium batteries might need some other specific charging voltage? Best to know what is needed if you have one of these batteries if you want a full charge from your alternator.

Not at all recommended for our application. The Odyssey manual discusses this. Charging at 14.7vdc is for a specific period of time for an “absorption” phase” using a programable charger, not for continuous float on an alternator output voltage. This would be typical if using the battery in a deep cycle application, not what we do. A long enough series of flights and you cause damage. Typical float voltage for a fully charged battery is more like 13.6-13.8vdc - just like your car. For our typical use, 14.2vdc is a good float voltage.

My Lancair neighbor who flew his plane around the world attributes one of his three Odyssey batteries failing after a couple of 30 hour flights to high alternator output voltage, his primary alternator was set at 14.3vdc.

My experience is to set the alternator output voltage at 14.2 - 14.3vdc. For all three RVs I installed two PC-625 batteries (slightly lighter than the 680 but a little more Amp-hr and CCA). I replace one battery every three years - so neither battery is more than six years old. I do this to have some confidence in battery capacity. The pulled battery goes on to a second life in the law tractor or neighbor’s John Deer for another three to four years. The airplane alternator is set to 14.2 - 14.3, and the lawn tractor is whatever it does (I assume 13.8vdc).

I would never fly the plane if either battery was abused (depleted). This causes damage reflected in reduced battery reserve capacity even if you think you charged it back up. These batteries as so cheap and widely available that there no reason not to replace it if abused.

Side note - I never leave a battery on a charger (or battery minder, battery tender, etc.).

Carl
 
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I agree that battery voltage is the thing to monitor. My alternator charges at 14.4V nominally. I got 10 years out of my first PC680 and the airplane was infrequently flown in the last 5 years of that. The next PC680 got 6 years before it was removed and replaced with the current Shorai LiFePO4.
 
Problem found (?)

Problem solved... I think anyway! Here is what I have pieced together.

During the ADS-B install, I saw the tech poke a metal mirror behind the bus to check the mounting of the ECHO-box. Next, I noticed sparks fly as he touched hot to ground with the metal mirror. I did not think much of it at the time but I'm pretty sure he shorted out the "Alt Bus" breaker (see image arrow), a 40amp breaker. After the shop completed the job, this breaker needed to be reset (by me just prior to departing).

In thinking it through, I suspect that the breaker was damaged by the short, so today I tested it with a meter. Sure enough, this breaker could not be reset and is totally fried. This explains why the alternator was not charging and, unbeknownst to me, the battery simply ran down in the first 20-25 min of flight. When I turned on Nav lights and pitot heat, everything just winked off. I'm going to pull the alternator and bench check it and I've ordered a new 40amp breaker from AC Spruce and I'll probably get a new battery to be thorough and complete.

I blame the avionics shop for this issue and I'll be taking it up with them, of course I'm also at fault. In retrospect, this has all the makings of the 'accident chain' (rush job, dead battery take off at night, shoddy shop technique, not being familiar with panel... etc.). I almost paid a heavy price and had I simply not flown, it would have broken the accident chain of events. I feel pretty lucky and am ready for 2020 to be over.
 

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Low volts - high amps

A buddy had a problem today. His battery was a bit low, but did start. After that, his low volt light was flashing and his amps were around 36. He freaked out and called me to check it out. Airline pilots! After charging the battery for a bit, we started it up and it was just fine.

The takeaway is: A low battery will draw a lot of amps - so much so that the voltage may sag enough to set off the lv alarm. He was convinced that his alternator wasn't charging even though he had seen 36 amps. If he had brought the RPM up, the alternator would probably have put out even more amps at a higher voltage and maybe even blown his B-lead breaker. With no low volt alarm, he might have been golden - at least until heat damaged the alternator.

Ed Holyoke
 
wiring diagram

Problem solved... I think anyway! ...
Thanks for the update. If you don't already have one, I think it might be very useful to create a clear wiring diagram. You might also take some time to test various failure modes, since from the diagram it says you have electronic ignitions. If you lose juice, you could lose your engine. Also, if you can, I'd check to see if these failure modes are documented in the POH. If not, I think it would be very wise to discuss with the builder (if you can) to see if they can walk you through the wiring design.
 
This has been a very constructive thread. Kudos to the Mark, the OP, and his approach to an introspective analysis of the chain of events causing the problem. There is no question his full disclosure of the event as a whole, while pointing out the mistakes shows an honest and positive attitude toward exposing an incident. He knew this would stir up a passel of opinions and went in head-first. I claim guilty to being in similar situations where I was part of the chain of events that caused trouble. And I know I am not the only one here reading this thread who has been involved in similar. I am not trying to blow sunshine around a serious event. I am just glad we have the VAF venue to debrief these situations matter of fact with honesty. This integrity approach will help me learn more about failure modes and the lessons learned are documented here for anybody who is interested. Thanks, Mark, and the others who have offered advice.
 
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A buddy had a problem today. His battery was a bit low, but did start. After that, his low volt light was flashing and his amps were around 36. He freaked out and called me to check it out. Airline pilots! After charging the battery for a bit, we started it up and it was just fine.

The takeaway is: A low battery will draw a lot of amps - so much so that the voltage may sag enough to set off the lv alarm. He was convinced that his alternator wasn't charging even though he had seen 36 amps. If he had brought the RPM up, the alternator would probably have put out even more amps at a higher voltage and maybe even blown his B-lead breaker. With no low volt alarm, he might have been golden - at least until heat damaged the alternator.

Ed Holyoke

This is especially true if you have a Lithium battery installed. I am running a small 40 Amp alternator and voltage will sag from my normal 14.2 down to the mid 13’s or so until the battery gets charged. Lithium batteries will pull in very high amps. This is also why you want to match alternator output correctly to the size lithium battery you have installed. To large a alternator output can be trouble for the battery.
 
I have recently developed an erratic alternator output shunt amperage indication on my glass panel as well as an apparently failed red cube. During these intermittent amperage reading outages, the voltage from the two alternators has remained steady at their respective set points (they are in cascade with the main at 14.3 and the backup at 13.6 if memory serves).

Bottom line on top - I never pay attention to the amperage reading except when the EFIS lady admonishes me to "Check amperage!" At that point I note that the shunt reading is fluctuating, sometimes negative, and therefore not reliable. A simple glance at the voltage holding steady in the 14's on the main alternator (and the 13's on the backup) under a 20+ amp load from the avionics and lights is all it takes to assure me the fault is in the shunt wiring and not the aircraft charging system. Therefore, the shunt is coming out as an unneeded accessory, and will be donating its wires (potted firmly in the firewall pass-through) to the replacement red cube in its new FWF location so that I don't have to drill a new hole and mount a new pass-though just for it.
May be useful to figure out why this is happening first though. The shunt itself cannot fail this way (unless you have a hall effect current sensor), so there is something wrong in the wiring or EIS.
 
May be useful to figure out why this is happening first though. The shunt itself cannot fail this way (unless you have a hall effect current sensor), so there is something wrong in the wiring or EIS.

The shunt is not the problem - it's the wiring from the shunt to the EMS sensor. It's literally millivolt-sensitive - any corrosion or poor connection makes a large sensor error.
 
Man I can relate to the feeling. I lost my alternator halfway between the west coast of Cuba and the Yucatan peninsula on a flight from Key West to Cozumel. It was 50miles of open ocean either way so I opted to continue on to Cozumel and avoid landing in Cuba without prior permission. :eek:

Luckily at 130KTAS it was less than 30minutes of flying with lots of ships below us. I was so glad I have pMags with built in generators in case my main battery quit. With my 25AH main battery, and load shedding as much as I dared, I landed with the main battery still showing 12v.

It turned out to be a blown 60A ANL fuse, I didn't even know I had, on a the 70A alternator output circuit. It now has the proper 70A Slow Blow ANL fuse.

:cool:
 
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What model alternator do you have? (BTW, not a fan of ALT breakers...)

Mine is a Lamar unit and it was pulled and bench tested (after a 'jump start' followed by losing electrical in flight). The alternator passed but as I said the 40amp breaker got fried so I could not reset the Alt bus after total electrical failure.
Mark
 
Mark, so glad you made it safely.
Aviators, when you are doing your flight plans it is wise to always consider this type of failure and try to mitigate the risk!
Mountains at night= two engines, two electrical sources
 
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