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Dead battery

NDrv8r

Well Known Member
Of course I have never left the master switch on, but I have heard of plenty of folks who have.

I am working on a master minder that looks at buss voltage. If the buss voltage is less than 13v, you can assume the alternator is not putting out. at that time there will be an output to light a low voltage light, and then after a period of time of low voltage, it will have an output to actuate a relay that can turn on the strobes, and or turn on a sonalert or other warning device. This would be installed on a pull type circuit breaker so you don't have a warning blaring at you if your alternator goes kaput in flight.

My question is;
1. is this worthwile?
2. assuming it is worthwile, what should the time between the low voltage warning and the "turn the master off dummy" warning be?


If using this without an enclosure is acceptable, I can see about a $30 cost.
 
I'll take two!

1w8es.jpg
 
Of course I have never left the master switch on, but I have heard of plenty of folks who have.

I am working on a master minder that looks at buss voltage. If the buss voltage is less than 13v, you can assume the alternator is not putting out. at that time there will be an output to light a low voltage light, and then after a period of time of low voltage, it will have an output to actuate a relay that can turn on the strobes, and or turn on a sonalert or other warning device. This would be installed on a pull type circuit breaker so you don't have a warning blaring at you if your alternator goes kaput in flight.

My question is;
1. is this worthwile?
2. assuming it is worthwile, what should the time between the low voltage warning and the "turn the master off dummy" warning be?


If using this without an enclosure is acceptable, I can see about a $30 cost.

Hook up to the main bus a relay that closes at 13 or less volts. This circuit is wired to a small siren with a push button that defeats the siren when it activates another relay that opens the circuit. This is for when the master switch is turned on before start.

After engine shut down, voltage will drop and the siren goes off again reminding the pilot the master switch is still on. There's no guarantee he will not push the defeat button and leave the master switch on, but at least we tried. :)
 
Dead Battery

Of course I have never left the master switch on, but I have heard of plenty of folks who have.

I am working on a master minder that looks at buss voltage. If the buss voltage is less than 13v, you can assume the alternator is not putting out. at that time there will be an output to light a low voltage light, and then after a period of time of low voltage, it will have an output to actuate a relay that can turn on the strobes, and or turn on a sonalert or other warning device. This would be installed on a pull type circuit breaker so you don't have a warning blaring at you if your alternator goes kaput in flight.

My question is;
1. is this worthwile?
2. assuming it is worthwile, what should the time between the low voltage warning and the "turn the master off dummy" warning be?


If using this without an enclosure is acceptable, I can see about a $30 cost.

If you are going to that much trouble in circuit design why not have it turn the master power off. That way you won't have to go back to your plane.
 
Dummies

My question is;
1. is this worthwile?
2. assuming it is worthwile, what should the time between the low voltage warning and the "turn the master off dummy" warning be?

My 1975 Cessna 182 came with a low voltage warning from the factory. Worthwhile? Perhaps, it made you look at the voltage indication. As to a complex "master on" warning, I once worked for a fellow that had a real talent for leaving the master on in his Aerostar. We cured him by hardwiring the rotating beacon to the master switch. Simple, and very effective in a hangar.

John Clark ATP, CFI
FAA FAAST Team Member
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
What about a low oil press warning light?

Vans sells a low oil press switch which can run the hour meter AND remind you that the master switch is left on.

Actually the light warns you that you've a low oil press but that's what happens everytime you shut down anyway.

Then if you wire the swich to drive a bright red warning light on the panel, then it's easy to see that the master is left on after shutdown.

Another bonus would be that if the your nice and expensive EFIS ever tells you that the oilpress is low when the engine runs, then you could verify this by looking at the warning light.
If the light isn't lit, then the EFIS-indication might be wrong.... if you are in the air by then, an option would be to continue to the nearest airport instead of landing right away at the nearest farmfield....

This is the setup I'm installing in my second -7.

Here's a link to Vans web-store: http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1287468613-328-138&browse=ei&product=vans-tach
 
GRT EFIS wired to the main bus and the backup battery. If either switch is "on" the EFIS is operational......and obvious.
 
GRT EFIS wired to the main bus and the backup battery. If either switch is "on" the EFIS is operational......and obvious.

You'd think so, wouldn't you....yet early on, I left the plane and hangar with the Master on (dual screen EFIS merrily computing away...). :eek:

How about a stenciled "Check Master!" warning by the hangar door?

Checklists are great, but as soo as you make something foolproof, someone will invent a better fool!
Paul
 
After doing the shut down check list. I had the fuel truck come by. I turned the EFIS back on, to reset the fuel quantity. In a rush to get home, shut off the EFIS and forgot the master. Twice! So now I just leave the LED nav lights on all the time.
As far as check lists go they are great until you forget to lower the gear.

The lights are for idiots and I guess I qualify.
 
I just hooked up the alternator "idiot light". Engine not running or alternator failure illuminates a big red light.
 
Strobe lights

If you leave your strobes on all the time it is obvious as you close up the hanger that the master is still on. Works for me!

Gary Specketer
 
dead battery

Thanks for all the comments.

Turning the master off concerns me because it would put circuitry somewhere in the master control circuitry. I don't think I would want to introduce a single point failure node.


Panel lights won't do. We have standby horizons in our Encores that are lit up real nice when the master is off....until the standby battery is dead.

Check lists are great, until you are distracted. Any one hear of a gear up landing?

So if any of my hypothesis has any validity, you may want a short period of time with the master on after engine shut down. Now the line guy wants a fuel order, and your wife is reminding you of whatever, how much time till the noisy beeper goes off? 1 minute? 2?
 
My shut down check list has me leave my strobes on. Usually works! See my picture in post #2. For what ever reason that day I turned the strobes off. About an hour or so later I realized that, and headed back to the airport and discovered the master was on. The picture tells the rest of the story.
 
dead battery...strobes on

Taxiing in with the strobes on is effective, but kind of bright for folks on the line. With this gizmo, it can parallel the strobe switch and turn it on. In this mode, it does not change how you operate your strobes, or introduce a failure point
 
... How about a stenciled "Check Master!" warning by the hangar door? ...
Paul
I have a 'hangar exit' checklist posted on the door:
A/C switches OFF, Compressor OFF, Hangar Door Latched, Lights OFF
Not that I've ever forgotten any of those things of course, but just in case :rolleyes:
 
Along the same lines, be careful charging your battery. TWO pretty good RV-10 owners on this site have had some serious mis-fortune as a result of a dead battery. In order to protect said individuals we'll refer to them as "A" and "B".

A) Ran the battery dead by leaving the master on over night. Next day hooked up his handy prewired accesible battery leads after double checking power/ground hookup with his multi-meter. Next day he went out and turned on the master switch to many loud pops/bangs and smoke got let out of many wires - all in about a half second. After much study and picking up his multi-meter to do some troubleshooting, he noticed the red lead and black leads were reversed....yep, the battery was happy as a clam to be charged backwards. LOTS of expensive electronics had to be fixed.

B) Ran the battery dead playing with things in the hangar. Put on the charger when he went home and forgot to take it off of the high setting. Came back the next morning to lots of which fuzz around the wing/fuse section, all over the floor, etc.. Turns out his lead/acid battery boiled over and leaked the stuff all over the bottom of the plane, ruining lots of interior, cables, wire, etc.. Many hours with a toothbrush/water/baing soda to fix it, not to mention all of the parts that were ruined.

Anyway, just wanted to point out that you need to take care when charging batteries. I have many such stories, but those are two directly related to dead batteries. The smallest of innocent mistakes can cost lots of money. My apologies to "A" & "B", but hopefully nobody will know who you are! :)

Cheers,
Stein
 
If you are going to that much trouble in circuit design why not have it turn the master power off. That way you won't have to go back to your plane.

You certainly wouldn't want it powering down your master in flight after you lose the alternator. If you happen to be IMC and shooting an approach at the time that would be MOST inconvenient...
 
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High Tech World

What we need is for the EFIS folks to build in cell phone technology, so that your airplane could call you and say.."Hey, my battery is low." or "Hey there, my master has been on for over one-half hour with no oil pressure." But then you'd have to endure "Honey, could you pick up a quart of oil on your way to the airport?".
:eek:
 
Who done it?

I found my master switch on and battery dead a couple of times early on after I bought this plane last March. I would have blamed it on the co-pilot if it weren't an RV-3.... After you're inconvenienced a couple of times, you tend to modify your behavior so it doesn't happen again...
 
Iv'e NEVER done it either

Cough!

But JUst in case I ever do i put a noisemaker on a canopy open (tip up) switch..A simple limit switch and siren wired directly to the main buss.

If the contactor is energised the main buss is on and the noise maker circuit is live..Open the canopy, the switch makes and its LOUD!

Not that I have ever heard it you understand.

Frank
 
Any light helps!

After leaving the battery on and flattening it three times in three years, I finally just put a light on the instrument panel in series with the battery switch. So far, two years and no battery left on, knock on wood! I also like the idea of an oil pressure switch light, giving the same warning, but also providing other information.
 
In series??

, I finally just put a light on the instrument panel in series with the battery switch.

I hope you meant in parallel and not in series. If in series, if the bulb burns out or you remove it there will be no continuity.

If you wired the light to the hot side of the switch and then to ground it's OK.

Don:eek:
 
No more dead batteries

OK folks, Here is what I came up with.
I am in the process of installing, testing and configuring a Skyview 10", arinc 429, SV-261 transponder, D6 efis and hopefully an ACK elt. Any how there is a lot of power on testing.

I have the Odyssy battery and a Radio Shack 22-508 13.8v regulated power supply. I highly recommend this little power supply, it puts out 19 amps, its regulated just like a alternator would be.

Well occasionally it's not too difficult to forget that dang master on, and the Master reminder has saved my battery on a number of occasions already.

I have mine wired with a low voltage light and a beeper.

It is programmed like this:
at initial mastter on, it ignors the buss, but it blinks the low voltage light to let you know its alive.

When it sees 13V or higher, it arms the alarm warning, and turns off the low voltage light.
When the voltage drops below 13V, the low voltage light comes on steady and starts a 1 minute timer.
At the end of 1 minute the beeper (loud beeper!) goes off.
at this point you can hit the cancel button which resets the 1 minute timer, turn off the master switch or pull the circuit breaker for the warning circuit.

I have a batch of them available for $39.95 + 5.95 usps shipping.



You can paypal to [email protected] or
go to www.bullerent.com/masterreminder.htm for more info
 
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