Failure of Battery in Mooney Ovation

[Dale]

Recently I was flying back from River Ranch in central Florida. The runway has no taxiway so for takeoff you have to taxi down the runway, turn around, do your run up and take off. I did my run up, took off and about 15 minutes into the flight my g1000 turned off. Apparently, while trying to get off the runway quickly for other traffic, I forgot to turn on the alternator and my battery 1 went dead. I turned on the alternator and the g1000 came on and everything was fine until I got about 3/4 of the way home then the battery circuit breaker popped and would not reset. A few minutes after that the g1000 went dead again and the main alternator circuit breaker popped and wouldn’t go back in. I turned off the main alternator, turned on the back up alternator and switched to battery 2 and got the g1000 back up,with 1 radio, but it would not operate the electric flaps or the gear, so I dropped the gear manually and landed with the flaps up. I understand that the backup alternator on the ovation3 will not operate the flaps, gear, elevator or rudder trim. (Although you can operate the elevator trim manually). My question is two fold. 1. If the circuit breaker for the #2 battery could be reset, would the backup battery have lowered the gear if the backup alternator was on. My POH manual says once the backup alternator is engaged it cuts off operation to gear, flaps etc. and 2. Has anyone had a similar situation where you forgot to turn on the alternator in the ovation and the battery went dead. What procedure did you follow? Thanks.

 

 

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[LANCECASPER]

I've only been flying a G1000 for less than 2 months, but my panel flow after start is off from my previous airplane. I haven't taken off yet without the alternator on, but I've turned it on later than I like a couple times so far. What I'm doing now is immediately after engine start looking at MFD for the the RPMs to make sure it's where I want it and then at the oil pressure, then I look up at the annunciator panel where the ALT VOLTS red light is on reminding me to turn the alternator on, checking to see if it comes on line, and then complete the rest of the items.

Your experience reminds me of how important it is at annual inspection that a capacity check is done on both batteries. Soon after I bought this airplane I replaced both batteries. One was 13 yrs old (original to the airplane) and the other one was almost 8 years old. Not a chance that either of them would have passed a capacity test. With all electric (no vacuum) airplanes being the new norm, this is more important than ever. Glad you got it back on the ground safely.

[carusoam]

+1 for capacity tests

+1 for completing the run-up before the back taxi… if able.  (Avoid being near the end of the runway where less skilled people may be landing, for the extended period of time…) 

+1 for the second battery

+1 for the second alternator

+1 for Concorde batteries

 

Another challenge to be aware of…. If you drain a battery, then use it in flight… it can be over taxing to the charging system…

 

What battery did you have?  How old was it?

Best regards,

-a-

[Dale]

I had a Concorde battery. It was about 3 years old.


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[Schllc]

Dale, that was my first plane!

I think I have an extra set of keys I found.

if you want them, PM me an address.

I was always told to start with the alternator switch on, not to turn it on after starting....

[carusoam]

5 minutes ago, Schllc said:

 

I was always told to start with the alternator switch on, not to turn it on after starting....

That’s an interesting change… from the old analog day’s practice…

The O1s use three switches placed next to each other…

Master, Alternator, Avionics…

Operated in order… with start following the Master coming on….

 

With the advanced use of electronics for monitoring the engine for start…. Many things are built more robustly… and other things just got better protection from spikes…. 
 

Sounds like some old standard practices are starting to fall….  Like OWTs…

-a-

[LANCECASPER]

The M20TN POH says to start with ALT off, then turn it on after start.

[Schllc]

Yes, I am aware of the poh, and this is how I did it as well, until two very well known Mooney A&P’s told me it should always be started with the alternator switch in the on position. 
Wouldn’t be the first time I’ve run into a contradiction...

Is there a mechanical/electrical reason for this, or is it just procedural? 


 

[carusoam]

Or both…

1) Mechanical… it is a touch more friendly to electric spike sensitive devices….

2) Procedural… it is a touch more friendly to stressed memory fading devices… aka brains.

 

Let’s see if @M20Doc has any input for turning on the alt field switch prior to engine start…

Doc is pretty good with both mechanical and procedural views….  

Best regards,

-a-

[Guest]

I don’t believe that starting the engine with the alternator field switch ON, will cause any harm.  When equipped with a field switch I turn it on after starting and establishing oil pressure. It allows you to verify alternator fail lights, ammeter, and volt meter function.

Clarence

[ilovecornfields]

15 hours ago, Dale said:

. I understand that the backup alternator on the ovation3 will not operate the flaps, gear, elevator or rudder trim.

I wasn’t aware of this. So if you’re on battery #2 with the backup alternator on and you select gear or flaps down then nothing will happen? I would have assumed the gear and flaps would run off the battery.

[amillet]

With only one battery the J model POH says turn on before starting. 
I also just noticed annunciation light check is before starting. I’ve been doing it after 

 

[LANCECASPER]

1 hour ago, ilovecornfields said:

I wasn’t aware of this. So if you’re on battery #2 with the backup alternator on and you select gear or flaps down then nothing will happen? I would have assumed the gear and flaps would run off the battery.

Even if you have both ALT breakers pulled, a good #1 or #2 battery should allow you to run the gear motor or flaps. 

[LANCECASPER]

1 hour ago, amillet said:

With only one battery the J model POH says turn on before starting. 
I also just noticed annunciation light check is before starting. I’ve been doing it after 

 

Exactly follow your own POH.

These airplanes have their own specific wiring to the model and even sometimes within the model to a range of serial numbers, so a blanket statement form an instructor or whoever about how you should always do it this way or that way doesn't apply. Follow the POH specific to your own airplane

[LANCECASPER]

12 hours ago, Schllc said:

Yes, I am aware of the poh, and this is how I did it as well, until two very well known Mooney A&P’s told me it should always be started with the alternator switch in the on position. 
Wouldn’t be the first time I’ve run into a contradiction...

Is there a mechanical/electrical reason for this, or is it just procedural? 

Just thinking out loud and I'm sure I'll be corrected by someone a lot more knowledgable, but if the alternator is online while cranking I'm not sure what voltage is coming into the system, how stable it is and how that affects the voltage regulator, etc. If the POH on this application is saying to just use the starter and battery during start they must be isolating the ALT for some reason from the rest of the system until things are running and more stable. Again . .  that may not be the reason but it seems reasonable to me.

[GeeBee]

You are on the correct track. Every year I read about boaters who turn their battery switch off with the engine running or the output cable comes loose. The result is fried diodes. The situation is endemic enough that high end boats have a "field disconnect" on the battery switch so the alternator is turned off in the case of battery shut off.  

During engine start, you can have a battery low enough voltage it can spike the diodes. The best way to protect the alternator is to have the field off while switching the battery on or off.

https://balmar.net/wp-content/uploads/2021/11/PDS-APM-24.pdf

 

[Guest]

1 hour ago, LANCECASPER said:

Even if you have both ALT breakers pulled, a good #1 or #2 battery should allow you to run the gear motor or flaps. 

That’s how we do it in the shop.  I’ve found it too windy when running the engine with the plane on jacks.  Though it does sound good.

Clarence

[Dale]

The POH for my M20R Ovation3 says to start the engine with the alternator off. After the engine is started, then it says move the alternator switch to the on position.

Here is what I understand from my mechanics at this point about the good battery not operating the gear or flaps. They said if the first battery is depleted and the main alternator (the 70+ amp alternator) fails and I switch to the emergency bus (the backup 30 amp alternator) then it will look to the battery that is the lowest, if the battery circuit breaker is in, and even though I have a full charge In battery 2, the standby alternator will look to the battery with the lowest charge and if that battery is to drained and requires a lot of charge, it will disconnect the battery system. Consequently, no power to the gear, flaps or electric trims. They said the procedure is in my POH supplement for G1000 equipped ovation3’s. My POH manual is with the plane at the A & P’s as they check my batteries, alternators, landing gear and electrical system. I will go back and review that section when I get the plane back.

In the meantime, it will be important for me to go over electrical system failures with my Mooney instructor both on the ground and in the air. This occurred in nice clear VFR weather. Had this occurred in solid IMC, it would have been much more difficult to cope with under those conditions. I was fortunate that the backup alternator worked to get my radios back up and engine gauges back on. I also was fortunate to have practiced the manual gear extension with my instructor on several occasions. I also found the value in keeping my iPad with WingX on an independent battery, separate from the plane’s electrical system along with my skyradar system, as I can split the screen with gps position and synthetic vision on WingX. I also found the value in having my handheld radio ready to go should the backup alternator have failed. All in all, I was fortunate that this was on a full VFR day and not in solid IMC.

I also need to change my procedure for handling a dead battery. Probably switch to battery 2 first, get the g1000 operational and then turning the main alternator on. I will spend time with my instructor going over electrical system failures and the different procedures I need to use and go back and read my POH and supplement on the same. Thank you to everyone that commented. It was very much appreciated.


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[Boilermonkey]

Had a similar problem (ish) before in our Bravo.   The interior lights, which are not turned off by turning off the master, had been left on over night and somewhat drained the #1 battery.   I started the plane with battery #2 and then before turning the alternators and avionics on I switched back to battery #1.   A false thinking on my part that doing so would charge bat #1 faster, but I don't think that is the case.   Instead what I had done was put the less full battery back on the demand bus.....not a good plan.  I should have left it on bat #2 and left bat #1 off the bus trickle charging for the flight. 

Taxi and runup were fine, but after take off the ammeter was nearly pegged.  I didn't think that was good for the alternator or battery, so I turned off the avionics and alternators, switched back to bat #2, turned everything back on, and continued the flight.   Upon getting back that evening I put a charger on bat #1 and it's been fine ever since.

Lesson learned:   

+Interior lights are independent form the master switch.

+Fly on the most well charged battery

+Both batteries get charged the same way in flight (from what I understand)

[LANCECASPER]

13 minutes ago, Boilermonkey said:

Had a similar problem (ish) before in our Bravo.   The interior lights, which are not turned off by turning off the master, had been left on over night and somewhat drained the #1 battery.   I started the plane with battery #2 and then before turning the alternators and avionics on I switched back to battery #1.   A false thinking on my part that doing so would charge bat #1 faster, but I don't think that is the case.   Instead what I had done was put the less full battery back on the demand bus.....not a good plan.  I should have left it on bat #2 and left bat #1 off the bus trickle charging for the flight. 

Taxi and runup were fine, but after take off the ammeter was nearly pegged.  I didn't think that was good for the alternator or battery, so I turned off the avionics and alternators, switched back to bat #2, turned everything back on, and continued the flight.   Upon getting back that evening I put a charger on bat #1 and it's been fine ever since.

Lesson learned:   

+Interior lights are independent form the master switch.

+Fly on the most well charged battery

+Both batteries get charged the same way in flight (from what I understand)

I would only add a couple things to that.

Don't take off if you know either battery is dead. You may need it plus it adds a huge strain on the system when it's trying to recharge it. If your alternator happens to be weak you will certainly find out on that flight. The trickle charging circuits are not real effective on these airplanes and on your year Bravo there's an in-line slo-blo fuse which is commonly blown (or at least it has been on a few that I've seen). There's a service bulletin regarding that.

Also unless it is an emergency or close to it do not switch batteries once you've started the airplane. You can easy fry the switch and relay by switching it when the airplane is running. I exercise both of my batteries, but if it's an even date I use battery 2 for start up and flight. On odd days I use battery 1.

[carusoam]

Dale,

You are missing some details on a few points…

It takes a while to get them all…

Don’t be afraid to ask your mechanic a few times…. Or your CFI a few times…

 

it appears you have taken some things a bit too literally….

 

If I have this correctly…

You have a long body with the usual dual battery system…

Battery #1 is wired differently than number two…

you have a pair of alternators, so the vac system has been removed…

 

Either of the two batteries can operate electric motors for gear and flaps…. Even if the alternators are both turned off…

As far as the system searching for which battery is stronger….  You are the system… you push the switch for bat1 or bat2…

 

About bat1… it is connected to the keep hot circuit… which often includes the cigarette socket, baggage lights, and memory systems like the clock and radios…

the baggage light has killed many bat1s, so has a portable device left plugged into the cig socket….

 

A proper BatteryMinder may revive the week battery… but, with your level of experience with the system… you may find it better to start with a fresh battery.  Keep the week one for a spare around the hangar… it’s good to have that one for a particular reason…

 

Check to see if you have the more user friendly Emergency bus… or if all the decisions of what to shut off are yours as well…

if you only have a 20amp alternator, and both batteries are drained during the flight… you want to be extra careful to not exceed the 20amps

 

By the time this all happens for real…. You have had significant multiple failures, and weren’t able to land for a really long time….

 

Lets work on the POH procedures and discuss why you want to alter them… one step at a time…

 

Long Bodies were designed and built in the very modern era… their documentation is very full, and challenging to memorize…

read the POH chapters that apply and share with your CFI….

 

There is a big chance… you didn’t understand what he was saying, and he didn’t understand what you were asking… 

Keep in mind my writing isn’t very friendly… I’m still working on that.
 

PP thoughts only…

-a-

[Boilermonkey]

1 hour ago, LANCECASPER said:

I would only add a couple things to that.

Don't take off if you know either battery is dead. You may need it plus it adds a huge strain on the system when it's trying to recharge it. If your alternator happens to be weak you will certainly find out on that flight. The trickle charging circuits are not real effective on these airplanes and on your year Bravo there's an in-line slo-blo fuse which is commonly blown (or at least it has been on a few that I've seen). There's a service bulletin regarding that.

Also unless it is an emergency or close to it do not switch batteries once you've started the airplane. You can easy fry the switch and relay by switching it when the airplane is running. I exercise both of my batteries, but if it's an even date I use battery 2 for start up and flight. On odd days I use battery 1.

Do you know where the slo-blow fuse is?   It might be worth checking at oil change....

I've also thought about installing a more friendly way of trickle charging both batteries when it's in the hangar.  I've seen two methods.   Putting connectors near the TKS fill port.  I've also seen small wiring fed through the hat rack.   Anyone have opinions on that?  

I'm familiar with the advice to not switch the batteries once started.  However, I would think it is ok if the alternators and avionics are off-line.  I realize there is still some load, but it would be much less.

 

[Schllc]

5 hours ago, LANCECASPER said:

Just thinking out loud and I'm sure I'll be corrected by someone a lot more knowledgable, but if the alternator is online while cranking I'm not sure what voltage is coming into the system, how stable it is and how that affects the voltage regulator, etc. If the POH on this application is saying to just use the starter and battery during start they must be isolating the ALT for some reason from the rest of the system until things are running and more stable. Again . .  that may not be the reason but it seems reasonable to me.

I don’t believe any damage will occur as a result of doing it either way, and here is why I was so easily convinced...

No other piece of machinery with an alternator as simple as a riding mower, or as complicated as a 500k rolls Royce, even has a switch to turn off the alternator, much less require you to utilize such an isolation, and their systems are arguably no less complex or sensitive. There are voltage regulators, and fuses/breakers for surges, just like our planes. 
The alternators on our planes are no different than cars or boats, most don’t even start producing power at all until a certain rpm.
i don’t believe that a plane, at least one designed for an all electric system, is vulnerable in this way at startup, mostly because if it was, it would be just as vulnerable at power setting changes. 
I don’t really want to sound like I’m arguing, I’m not the poh is the final say,  

I’m willing to bet this is a holdover from older days, and procedural to check output, not to prevent damage.  I just can’t really see any logical reason the system would be at risk either way, and it’s easy to see if it’s producing power while running as your positive draw declines after startup.  Maybe one of the electrical engineers here can chime in with a more thorough explanation. 
That being said, while I always used the procedure in the poh until I was advised otherwise.....I  am probably going to go back to that now just to be on the safe side. 

[LANCECASPER]

2 hours ago, Boilermonkey said:

Do you know where the slo-blow fuse is?   It might be worth checking at oil change....

I've also thought about installing a more friendly way of trickle charging both batteries when it's in the hangar.  I've seen two methods.   Putting connectors near the TKS fill port.  I've also seen small wiring fed through the hat rack.   Anyone have opinions on that?  

I'm familiar with the advice to not switch the batteries once started.  However, I would think it is ok if the alternators and avionics are off-line.  I realize there is still some load, but it would be much less.

 

It's explained in SB M20-275 but the fuses are near the batteries. More recent Mooneys use circuit breakers in the tail section instead of inline fuses.

https://www.mooney.com/wp-content/uploads/2020/12/SBM20-275.pdf

 

I run my battery minder leads to the oxygen door, but if i had FIKI I'd use that door. I like those options better than having to leave the baggage door cracked open and ending up with critters in the airplane. 

 

Possibly, but if I'm on the ground and there's no emergency, personally,  I'd rather just shut down and restart on the other battery than risk the very expensive relay. 

 

[exM20K]

Do you know where the slo-blow fuse is?   It might be worth checking at oil change....
I've also thought about installing a more friendly way of trickle charging both batteries when it's in the hangar.  I've seen two methods.   Putting connectors near the TKS fill port.  I've also seen small wiring fed through the hat rack.   Anyone have opinions on that?  
I'm familiar with the advice to not switch the batteries once started.  However, I would think it is ok if the alternators and avionics are off-line.  I realize there is still some load, but it would be much less.
 

I had a 24V cigarette lighter socket installed on the back of the baggage compartment to power my BeKool. It is wired with a breaker but no diodes to Battery 1. This could probably be used to trickle charge that battery.