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Dead short of battery In flight


Scrapman1959

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KPvb to Kuno. One hour into flight voltage drops to 10.3 while amps are at 15. Cycled the avionics with no luck, then the masters with no changes. While searching for an appropriate place to land we lose everything in the cockpit except the 696. I had allready shed the AP and 430waas radio in the panel by manually popping circuit breakers. So we finished the flight with the skyview coming on every ten minutes or so just long enough to see the engine was all in the green. Landed with no problem with flaps at zero and no air speed etc. had Gutmans send a battery overnite, and everything fired up and worked just fine next day. The bad battery will not even accept a trickle charge. It has a dead short inside. Glad it was a nice day when this incident took place. Battery was less than a year old.

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Shouldn't your electrical system work fine with a dead battery? Mine has.

No, they had a dead short inside of the battery, lowering the internal resistance and causing a massive spike in current flow. This is an extremely dangerous condition that requires an alternator shutdown or it will start a fire.

 

You cannot turn off a battery either unless you have others in the system. Batteries smooth out the voltage spikes which are commonplace with permanent magnet generators and some alternator designs. These spikes can destroy avionics.

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The battery is the bigger of two sizes available on LS. It's orange in color and totally sealed up. No vents. I will get the make and model tomorrow. So when we were seeing 16 amps for the brief times the Dynon was booted up and on line, that should have been a message to pop the master for the alternator? I never gave any thought to that high amperage damaging the avionics. Guess we are lucky everything worked fine when we got the new battery in. One other thing to mention, when we installed the new battery, the moment the positive lead was touched to the battery terminal, the engine started spinning over full speed. Glad nobody was near the prop. Scared the hell out of us. Tapped the starter solenoid a couple times with a wrench and that cured it. The dead shorted battery must have stuck it in closed position somehow. Anyway, just a reminder to stay clear of the prop when installing a new battery or hooking cables/charger etc to a dead one. I know these planes are not be jump started though, correct?

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Wow!

 

1) I would seriously consider replacing that starter solenoid/relay. It should not stick like that, and may be damaged.

 

2) I just looked at the voltage specs of my Dynon D10A. It specifies 10-30v DC. That may or may not apply to your model, but you may have some built-in overvoltage protection right there!

 

3) I have jump started my Sky Arrow a couple times. I'd be curious as to the alleged potential harm. One reason not to do it is taking off with a marginally charged battery leaves one with little reserve should the alternator fail. VFR, and with backup avionics, that does not seem a huge risk by itself. And charging a fully depleted battery in flight in non-optimal - but it does seem to work.

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I once prop started a C150 that was totally discharged and found there was not enough of a trickle charge to excite the alternator, so it didn't charge at all in flight.

 

Is the Rotax electronic system the same?

 

Sorry for the thread drift. I understand propping a Rotax (which we're told we can't do but which we've seen YouTube evidence of) is not the same as starting with a battery jump start, but the question interests me, if I can be forgiven the diversion.

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Well, the plane can't really "know" whether the current flowing through the battery cables is from the aircraft's battery or a "jump" battery, so the actual starting should be identical. So no issue with the alternator not getting current.

 

The question is what happens when you disconnect the jump battery and fall back on a seriously depleted one. Historically, people just go fly. But plane's are more complicated now - remember what happened to that Diamond TwinStar!

 

http://www.flightglobal.com/news/articles/accident-ignites-da42-engine-row-213371/

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Good save scrapman I hope im as cool under pressure when my time comes!!

 

the first thing I thought of when I read this is the dead battery and the starter issue are related.... then i started going through that possibility in my head... keeping in mind i have been a mechanic for 20 years and i know there are vary few coincidences. .... if that starter solenoid somehow stuck on in flight what would happen ?? there is an over running clutch in the starter so it may not completely fry the starter (although there would be damage) it would create an large amperage draw and that continues draw may bugger the battery.

..... of course this is all just off the top of my head but i would be looking in a bit deeper if it was my bird!

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I know these planes are not be jump started though, correct?

 

When I had a dead battery, I jumped it.  On the CTSW here is a positive cable on the bottom of the cowl with a rubber cap for that purpose, positive lead goes there (after taking the cap off, lol) and negative to the exhaust pipe.  Worked great, I had to do it twice.  I assume the CTLS has a similar setup.

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3) I have jump started my Sky Arrow a couple times. I'd be curious as to the alleged potential harm. One reason not to do it is taking off with a marginally charged battery leaves one with little reserve should the alternator fail. VFR, and with backup avionics, that does not seem a huge risk by itself. And charging a fully depleted battery in flight in non-optimal - but it does seem to work.

 

Yeah.  When we jumped mine, some friends and I were taking a flight to a nearby local airport to just hang out.  When I went to start my airplane it was a no-go.  We jumped it off my car, thinking we'd fly up there and give my battery a chance to charge, and see if the battery was dead or just discharged.  When we got to the destination it was still dead and we used the jumper cables we'd brought to jump it again off the airport courtesy car.  :)

 

It's possible if the alternator failed, I would have lost some stuff.  But my airplane has backup batteries for both the EFIS and the 496 GPS, and has backup analog airspeed and altitude gauges.  So I probably would have lost the analog engine instruments and gotten alarms that I was on battery backup for everything else.

 

One interesting note, after landing the flaps would not retract until I turned off the factory halogen landing light.  The alternator at engine idle didn't have enough juice to run both with the avionics still on.  I since switched to a LED landing light and that cured that problem.

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The battery is the bigger of two sizes available on LS. It's orange in color and totally sealed up. No vents. I will get the make and model tomorrow. So when we were seeing 16 amps for the brief times the Dynon was booted up and on line, that should have been a message to pop the master for the alternator? I never gave any thought to that high amperage damaging the avionics. Guess we are lucky everything worked fine when we got the new battery in. One other thing to mention, when we installed the new battery, the moment the positive lead was touched to the battery terminal, the engine started spinning over full speed. Glad nobody was near the prop. Scared the hell out of us. Tapped the starter solenoid a couple times with a wrench and that cured it. The dead shorted battery must have stuck it in closed position somehow. Anyway, just a reminder to stay clear of the prop when installing a new battery or hooking cables/charger etc to a dead one. I know these planes are not be jump started though, correct?

All batteries have a vent to prevent an exposion. On the orange battery, it is a small round disk on top in the back. If the disk is missing, the contents of the battery vented.

 

I don't remember the details in the old thread about jump starting. I think it was an issue with the lithium battery in the LSi, but it was fine with the LS. Jump starting just isn't a good practice unless you want to sit on the ground for 20 minutes at 3.5k RPM to charge the battery.

 

Is the Rotax electronic system the same?

 

 

Rotax non injected use permanent magnets. I don't remember if the iS uses a field circuit.

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Good save scrapman I hope im as cool under pressure when my time comes!!

 

the first thing I thought of when I read this is the dead battery and the starter issue are related.... then i started going through that possibility in my head... keeping in mind i have been a mechanic for 20 years and i know there are vary few coincidences. .... if that starter solenoid somehow stuck on in flight what would happen ?? there is an over running clutch in the starter so it may not completely fry the starter (although there would be damage) it would create an large amperage draw and that continues draw may bugger the battery.

..... of course this is all just off the top of my head but i would be looking in a bit deeper if it was my bird!

In the 912 series, probably nothing. The sprag would never engage because the engine spins faster, so it would never load the starter, and thus the starter would put next to no load on the electrical system, and generate little to no heat either.

 

In a cont or lyc, they have bendix drives. That might chip a tooth before forcing the bendix to retract. Same thing though, starter would never load, so very little heat.

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The starter worked great this morning, everything normal on my flight to work. The flight back was 3.5 hours and I put the auto trickle charge on over the weekend. Did have a good scare crossing the Mississippi on the way to work this morning at 1700AGL had a gaggle of geese cross in front of me just 50 ft away and same altitude. It's that time of year, watch out everybody flying on the migration trails.

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  • 1 year later...

Hi,

 

Recently found this forum, Its a very informative resource & just wanted to add a bit to this thread. 

 

A few weeks ago I had a similar problem to Scrapman1959.

 

Started up normally but after 20-30 seconds the low voltage alarm came on showing 10.3v even though the generator was putting out 13.4

 

 

 

@ Scrapman1959 Did you ever end up replacing your starter solenoid/relay?

 

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I have had a couple occasions where the key does not spring back from the start position after the engine has started. Up until a few weeks ago I was always in the airplane and caught it right away. A few weeks ago I had a renter get a low voltage warning as he was taxiing out. He shut it off, but by that time the battery was already to low to restart. I told him what was happening and what to look for, recharged the battery and sent him on his way.

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Tom Baker, on 23 Jul 2016 - 11:27 PM, said:

I have had a couple occasions where the key does not spring back from the start position after the engine has started. Up until a few weeks ago I was always in the airplane and caught it right away. A few weeks ago I had a renter get a low voltage warning as he was taxiing out. He shut it off, but by that time the battery was already to low to restart. I told him what was happening and what to look for, recharged the battery and sent him on his way.

Hey Tom,

I am certain  the key wasn't stuck in the start  position because when I turned it all the way back to off, the starter stayed engaged still turning the motor.

What I am wondering is if Scrapman1959s "dead short" was actually caused by a faulty starter solenoid? 

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  • 6 months later...

Adding battery story happened today:

 

Started up / did all regular checklist and taxied out. All good and normal.  I had just requested takeoff clearance and then the entire panel went dead.   No efis, no avionics, no engine gauges.  Got the handheld out and informed tower i was heading back to hangar.  First thing i checked was the battery terminal connection  - voila, it was loose.  Glad this happened whilst i was still on the ground.   Anyways,  just sharing this story as a reminder to check the tightness of the battery connector. 

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Tom, do I read it right that the starter on your plane remained engaged while the renter was taxing and this is what ran down your battery?  If you find this happening, what is the remedy, just nudging the key back to "run" position?

 

Auscts, I would think this is a stuck solenoid unless the switch contacts are spring loaded and are corroded and might remain stuck in the "start" condition even if the key is turned to "off"?

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Tom, do I read it right that the starter on your plane remained engaged while the renter was taxing and this is what ran down your battery?  If you find this happening, what is the remedy, just nudging the key back to "run" position?

 

Yes, the solution until the switch is replaced is to simply return the key from the start position to the run position.

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