Battery Drain

[ddkflyer]

I just purchased a one owner 1989 M20K.  Low time, always hangared, mint condition.  It just came out of annual, with a new battery.  It sat for 2 1/2 months before I had a chance to fly it.  Upon first preflight, battery only had 22 volts.  Engine cranked once, but would not start.  Previous owner always used a battery minder, as he did not fly much.  Owner says that the battery drain is normal.  My CFI says it should hold out for a few months, at least.  

Are any of you aware of a constant drain on the battery, and if so, what is the source and what is the fix?

Thanks, this is my first post, and I look forward to the feedback.

[MooneyBob]

Welcome and congrats on your K.

I always though that with the Master off there is no current drawn from the battery at all. Unless there is a watch or something like that to bypass the master and connected to the battery all the time. Otherwise the battery should hold the charge for few months.

[DonMuncy]

The clock, the interior and baggage area lights are not on the master.

[kortopates]

Check out the age of your battery in your log book and read up on battery's in this article. http://batteryminders.com/prints/aviation/tac_concorde_still_excels.pdf Sent from my iPad using Tapatalk

[kortopates]

The clock, the interior and baggage area lights are not on the master.

The clocks run on its own battery. Good point about the interior lights, but they'll drain the battery in a weekend. Not sure, but the Encore model may have the timer on the interior lights to prevent that.

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[larryb]

Clock in my 84 j is indeed on the ship battery. But perhaps some models have an internal clock battery.

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[kortopates]

Clock in my 84 j is indeed on the ship battery. But perhaps some models have an internal clock battery.

K's do, at least the 252's, not sure when they started, but they drain so little. 7+ years on an alkaline AA. Are you sure the power isn't just for lighting? Sent from my iPad using Tapatalk

[DonMuncy]

My K (231)runs off the ships battery. How much trouble is it to change the battery in the internal battery type.

[LANCECASPER]

Not sure where you'e located, but with cooler weather in most parts of the country this winter, I'm surprised you got any crank after 2-1/2 months. Especially if the last landing may have been made at night, taxiing in at low RPM with taxi and landing lights on could have left you a little low to begin with. The Batterminder is well worth it. 20 years ago I used a 12 V Battery Tender from a motorcycle on my 231. Later on I used a Battery Minder to charge both batteries at the same time in the Bravo I had and now I use a 24041-AA-S5 Battery Minder in my Encore. I run the connector into the APU plug door so it's easy to access. And yes I'll take 5 minutes and pull of the wiring before my next annual. : )

 

Just make sure you get the correct one for your battery (My Concorde battery uses a special one that has an S5 suffix - works awesome though). In addition to that once it brings it up to charge it will run through a desulfate mode also to extend the life of your battery. It pays for itself and it's nice to know that you're going to start off with plenty of cranking power. Nothing worse than pushing out of the hangar, loading up everything, pre-flighting and then no cranking amps. The best price I found on the one I needed with shipping (no tax) was at Batteryplex.com

[larryb]

K's do, at least the 252's, not sure when they started, but they drain so little. 7+ years on an alkaline AA.Are you sure the power isn't just for lighting?Sent from my iPad using Tapatalk

I am positive. Early in my ownership I knocked the interior switch accidentally and killed my battery. The battery never recovered from that and had to be replaced. I learned the system then. Not wanting a repeat I took out that fuse and that killed the clock. Later on I put back the fuse and removed the interior bulbs. Now I have a clock that runs but does not keep time, thinking about a davtron digital replacement. Sent from my iPad using Tapatalk

[DonMuncy]

Larry,

I designed and installed an electronic circuit which allows the interior and baggage lights to be used, and will stay on for 8 to 10 minutes and then turn off. Beats worrying about whether you might ruin the battery by leaving the light on. Naturally, I did this after I ruined a battery too.

[kortopates]

My K (231)runs off the ships battery. How much trouble is it to change the battery in the internal battery type.

I guess if you could change the single alkaline battery without R&Ring the clock it would be real easy. But I probably took 1/2 hr doing it. More recently I've replaced my Mooney clock with a Guardian CO2 detector that includes a clock and some other features. Now every 5 years I send the unit in for a new CO2 sensor rather than replace its battery. Sent from my iPhone using Tapatalk

[kortopates]

I am positive. Early in my ownership I knocked the interior switch accidentally and killed my battery. The battery never recovered from that and had to be replaced. I learned the system then. Not wanting a repeat I took out that fuse and that killed the clock. Later on I put back the fuse and removed the interior bulbs. Now I have a clock that runs but does not keep time, thinking about a davtron digital replacement.Sent from my iPad using Tapatalk

That's a painful experience! I went through 12 yrs of ownership thinking it would never happen to me and then I got bit after removing two 29er Bikes out of the back and didn't notice I hit the switch. I am pretty sure it won't ever happen again after that painful lesson. Plus I really like the lights in the evening.

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[carusoam]

FF / used also may have a memory...

Best regards,

-a-

[wiguy]

 If the plane is going to sit for periods I would get a battery minder of some type. I have one & only plug it in occasionally, works great.

[LANCECASPER]

I just purchased a one owner 1989 M20K.  Low time, always hangared, mint condition.  It just came out of annual, with a new battery.  It sat for 2 1/2 months before I had a chance to fly it.  Upon first preflight, battery only had 22 volts.  Engine cranked once, but would not start.  Previous owner always used a battery minder, as he did not fly much.  Owner says that the battery drain is normal.  My CFI says it should hold out for a few months, at least.  

Are any of you aware of a constant drain on the battery, and if so, what is the source and what is the fix?

Thanks, this is my first post, and I look forward to the feedback.

 

See if he'll sell you his battery minder.

[Guest]

Possibly a defective new battery, or was never serviced correctly from the start by the maintenance shop. A healthy battery should hold its own for quite some time.

Clarence

[mikesideup]

This happened to me when I had a K model. I bumped the overhead cabin light switch when exiting or entering so the light was on all the time . Set me nuts for about a month. Worth checking.

[rbridges]

like someone else said, shouldn't a left on light kill the battery in a few days?  if he still had some juice at 2 1/2 months, I'd think it's something with a slower drain or a faulty battery/alternator.