Dead Battery Culprit

[Piloto]

Two days ago after a previous short trip to KORL I found the battery on my M20J dead. I connected the ground power cable and found out that the overhead light was on. This light can be turned on with the master switch off thus draining the battery even if the master is off. It looks that while pulling out large boxes of luggage I accidentaly turn on the light. This is the second time it happens to me but luckily both has been in my hangar. It came to my mind the scenario if this happens at one of the remote airports I fly to with no FBOs or someone to help.

 

The lights are directly connected to the battery to allow them to be turned on at night during un/loading without turning the master on. Nice feature but it can get you into trouble. Today I disconnected the center wire of the light switch from the battery supply and connected a 3" jumper wire from the switch to the stall horn B+ side. This way there is only power to the lights when the master is on. The modification is very easy to do since the stall horn is next to the switch. It took no more than an hour to do it. I am also replacing the light bulbs with LED direct replacemet from Dialight. These consume 1/10 the current of the old incandesent.

 

This may sound trivial but I do not want to be stranded at TJMZ with all the luggage and family onboard but no power to crank the engine to get home.

 

José        

[johnggreen]

The overhead light on my Bravo is wired in like fashion.  I lost a battery like that as the result as a complete discharge.  The biggest problem is not leaving it on, but accidentally hitting it with my left hand while in flight, then shutting the airplane down without knowing it is on.  Since there are other interior lights which are on the master buss, the best solution is to simply remove the bulb.

 

Jgreen

[Jamie]

It's stuff like this that may one day motivate me to sell the Mooney (I know, I know... ) and build something. The engineering technology and mistakes present when mine left the factory are essentially frozen in place. Can't fix it unless someone has gone through the incredibly expensive process of getting something approved and I buy their incredibly expensive solution.

 

And legally, about all I'm allowed to do is remove the bulbs. Technically, I can't do the rewiring, right? That would have to be by an A&P?

[larryb]

I also lost a battery to this, and I also removed the bulbs afterwards.

[jetdriven]

You may need that bulb if your instrument lights fail at night.  AFAIK the newer Mooney's have a timer that shuts off the ceiling light.   The stock bulb draws a couple amps. This one draws .3 amps.  Thats what we have.

 

http://www.amazon.com/gp/product/B009DR8BJI/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1

[231Pilot]

I had it happen when I had my J, made it part of my end of flight check list to make sure the light was turned off before I secured the aircraft in the hangar or at a tie down when traveling.  Problem eliminated at no expense except for the red face from letting it happen in the first place.

[Ned Gravel]

Mine is no longer independent of the master switch - if it was before. It was completely disconnected till last year when I pulled the overhead plastic, put in new soundproofing, and reconnected a new cabin speaker. Sent from my iPad

[N33GG]

Come on Jose...some of the best memories my family has are the times we got stranded somewhere with a dead battery. You are cheating your family out of adventure opportunities!

[RJBrown]

Drained a 3 month old battery in the dead of winter. It froze and was junk there after. Definitely something to check every time. Children in the back seat love to touch everything they can reach.

[Piloto]

Come on Jose...some of the best memories my family has are the times we got stranded somewhere with a dead battery. You are cheating your family out of adventure opportunities!

 

Not when everyone is saying "I wanna go home", "I am tired of grandma", "this place sucks, it never stop raining and is hot". 

 

José

[Piloto]

Drained a 3 month old battery in the dead of winter. It froze and was junk there after. Definitely something to check every time. Children in the back seat love to touch everything they can reach.

I was lucky to have an AGM Concorde battery. They can be recovered after a deep cycle discharge. I charged at 10 amps for one hour and then float charged at 1 amp for two days and got a full charge voltage. AGM batteries are deep cycle discharge batteries. This means they are designed for total discharge applications and can be recharged again for another deep cycle discharge. They are perfect for cold weather since there is no water to freeze.

 

José  

[Piloto]

I also lost a battery to this, and I also removed the bulbs afterwards.

This is the best quick solution. I never had any real need for the overhead lights. When I travelled with family at night my son would be playing Mario on his video game, my wife would be asleep and my mother in-law would be praying while counting beads on the rosary (so much for confidence on me)

 

José

[duke]

My eagle is the same way. Clock, cabin and bagage lites wired directly to #1 battery through a .5 amp slow blow fuse.

Baggage lite has a momentary contact switch which is ok. I am going to have a talk with hanger elf and try to come up with a shield for cabin switch.

[Royski]

I was all set to go flying yesterday and but had a dead battery, probably after bumping on the infernal lights unloading baggage after the previous flight.

 

I wonder about either adding a guard over the switches to prevent this, or maybe adding the timer mentioned above.

[CoachTom]

Jose',

Do you have a part number for those lights from Dialite?

[Piloto]

Jose',

Do you have a part number for those lights from Dialite?

This is the part number on the Digi-Key Catalog 

350-2159-ND

14V T3 ¼ White Dialight LED Lamp

$7.046

But from my experience with them they are too dim when compared to the incandescent. They are more applicable to instrument dial  backlight than for area illumination. Not worth the money. For me, rewiring the lights to the master switch is the surest way to insure no accidental battery discharge. If you need a light for the baggage area you can velcro or glue on top one of these portable closet LED lights that operate on batteries and gives you more direct light than the cabin one.

 

José 

[PMcClure]

I think the newer models have a timer set on the overhead light. 

[wolftimj]

Another dead battery via baggage light story. Batteries fine after 12 hours of flying... Anyway, several people have said that newer models have a timer. I have a 1997 model without a timer. Can I install one? Part number? Where do you put it?

 

Tim Wolf

N9159C

[DonMuncy]

Tim,

I sent you a PM.

[PMcClure]

Easy solution - buy an Ovation, they have 2 batteries!!!

[bonal]

Got a check list for shut down just add the item to check all switches including the light as part of your shut down procedures.

[wishboneash]

Last weekend my battery was completely discharged as well. I don't believe any circuits were on, including lights, but the battery was completely deep discharged. I removed the battery (Concorde RG-35AXC) and noticed the ground connection was oxidized (green oxides from the copper). The positive terminal was clean. I sandpapered it and cleaned both terminals and connectors. The charging current was close to 18A at the beginning with 13.5V applied. It completed the charged overnight. The plane started up fine the next day. I checked the battery after the flight and the next day - the charging current was under 2A when I tried to charge it. So I think, the issue is resolved. Battery terminal corrosion is something to check for occasionally.

[BobAustin]

OK...my stranded with dead battery story.

 

 Back in early 90's we went to the Baja for fishing in our 85 M20J.

You know what happened when we took the bags out...bumped the switch and left it on for 5 days.

 

This was at a dirt strip at a fishing "resort" with no facilities.  To compound things I had failed to bring the plug in jumper cable...

Luckily ours was the last year for 14 volt battery.  Finally found a guy with a van and a set of trashed out jumper cables.

Got my wife into the pilot seat told her what to do, had to hold the jumper cable on the battery with side door removed, got guy to race his engine and wife to crank.   IT STARTED... blowing sand on me while I paid the guy, remounted the battery door...climbed over my bride and flew back to Texas over 150 miles of the Sea of Cortez. 

 

No bulb for me.  LED flashlite is fine.

[cliffy]

Just a thought-

Any time a lead/acid battery is completely discharged it losses some "capacity". The amount of loss is related to how long it was flat and how many times it has happened AND how old the battery is. The next time you fly and have to depend on that battery for radios (alternator failure!) you may not have much battery power available until things go quiet and dark. Your battery is your last line of defense if you loss your alt. It pays to keep it perfect. It may save your life!

If you fly IFR with one alt/gen and one battery you might want to have a battery capacity check done after a discharge event to see how much is really left in your battery if you need it. You also might want to do this if your battery is 3 years old or older.

Here's a question to ponder-

When was the last time you had to change your battery because it failed?

You probably found out it was bad when you came put to fly and the engine wouldn't turn over-right? Starting uses very little of the total capacity of a good battery. If it won't start the engine there was very little of it left anyway.

What would have happened if on your last flight before you changed it you were IFR or night and lost your alternator? How much help do you think THAT battery would have been then?

Lights? Radios? Instruments? GEAR?

[larryb]

Thing is, a capacity check draws the battery flat and reduces its life.