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  #1  
Old 01-22-2022, 02:33 PM
garrys garrys is offline
 
Join Date: May 2006
Location: Odessa, Florida
Posts: 64
Default slow battery drain

I have a slow drainage from my battery. It won't hold the charge from one weekend to the next and I have been trying to track this down from when I first built the plane (7-A) 9 years ago. I have replaced the battery (Odessy 680), replaced the solenoids, etc. When fully charged it reads 12.4 amps. If it sits for a week it drops down to 11. 3 amps, which isn't sufficient to start the plane.
I am the most ignorant builder ever when it comes to stuff electrical. A hanger neighbor stopped by and put a gauge on and said the battery is drawing 3 mili-amps (whatever that is) when the master switch and everything is off. The only thing I can think of is the analog clock which doesn't go through the master switch, but I can't believe that clock should drain the battery so quickly. Keeping in mind I am totally ignorant on things electrical, does anyone have any suggestions on how to proceed finding where/why the battery drains? You can imagine how frustrating it is to promise a friend a plane ride only to find a dead battery. Thanks in advance!
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  #2  
Old 01-22-2022, 02:42 PM
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Sam Buchanan Sam Buchanan is offline
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Well.....why not disconnect the clock and see if that fixes the problem?

Try the easy stuff first.
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  #3  
Old 01-22-2022, 02:52 PM
garrys garrys is offline
 
Join Date: May 2006
Location: Odessa, Florida
Posts: 64
Default slow battery drain

Thank you Sam! I agree that would be a good first step. Unfortunately at age 78 with a bad back I'm just unable to contort my body to get behind the panels. I guess I'll have to hire a youngster to do that for me. As long as he's there, is there anything else we should be checking or disconnecting?
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  #4  
Old 01-22-2022, 03:02 PM
sailvi767 sailvi767 is offline
 
Join Date: Sep 2010
Location: Charlotte NC
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I assume you mean volts not amps on the values that you posted. If so 12.4 is low for a fully charged battery. You should see 12.8 or better. I see 13.1. What is your voltage when flying? You should see 13.8 to 14.4. Itís possible your voltage regulator is putting out very low voltage or you have something failed in the alternator causing the battery to never fully charge.
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  #5  
Old 01-22-2022, 03:22 PM
No_0ne No_0ne is offline
 
Join Date: Jan 2016
Location: Martin, Tn
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It sounds like you may have a couple of problems. A reading of 12.4V (I assume you meant volts rather than amps here) would be at the low end for a healthy AGM battery after several hours in the rest state - I would rather see closer to 13V initially. A 3 milliamp parasitic draw should be fine on a fully charged battery for a week, however if your battery is starting off on the low side it could conceivably be problematic. Measuring that small of a drag is also difficult, you need a sensitive meter for that, try measuring the parasitic drag with different meter again. I would want to find out what the alternator is putting out when the engine is running, it should be somewhere in the @14V range for output, if that's off then you may not be fully charging the battery during your flights. How old is your replacement battery? How often do you fly, and for how long? Batteries do age over time, coupled with an alternator that's not charging properly you might have a battery that's right at the point of failure. Check out your charging system, and if possible have someone recondition your battery, that way you start out in a known condition. It's also possible to do a battery capacity check, however that takes equipment beyond a multimeter.

Last edited by No_0ne : 01-22-2022 at 03:24 PM.
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  #6  
Old 01-22-2022, 03:28 PM
Richard Connell Richard Connell is offline
 
Join Date: Aug 2006
Location: Sydney Australia
Posts: 350
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What sort of alternator and VR do you have?
If you have the regulator voltage sense connected to the always hot bus that will show these symptoms.
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  #7  
Old 01-22-2022, 03:45 PM
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MacCool MacCool is online now
 
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Nine year-old battery? With a fully-charged voltage of 12.4v? I don't know whether you have an internal short in the plane, but that's a sulfated battery and it's toast.
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Last edited by MacCool : 01-22-2022 at 03:48 PM.
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  #8  
Old 01-22-2022, 05:47 PM
garrys garrys is offline
 
Join Date: May 2006
Location: Odessa, Florida
Posts: 64
Default slow battery drain

Correction on my original post. My battery is only 2 months old and I am virtually positive it's in good shape. I meant to say Volts rather than amps. I have no onboard way to read volts or amps. I have to do it with a cheap multimeter. My alternator and regulator is standard Vans firewall forward stuff. How do I measure the charging system output which the plane on the ground in the hanger? What do y'all think of this idea.......with*the engine and master off hook up the multimeter to read volts. Then close each circuit breaker one at a time. If the voltage reading changes does this mean something on that circuit is drawing power? Dumb idea? I told you I was stupid. Thanks to all who responded!
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  #9  
Old 01-22-2022, 06:45 PM
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MacCool MacCool is online now
 
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Quote:
Originally Posted by garrys View Post
Correction on my original post. My battery is only 2 months old and I am virtually positive it's in good shape.
Hmmmm....if its fully-charged voltage is 12.4 volts, I strongly contend that it is not in good shape. In fact, I'd be more likely to say that it's toast.

You could pull it out, take it to Autozone, and have it load-tested. You may well have a short somewhere in the wiring and that may have discharged it enough times that it's sulfated, but as it stands right now....I'm sayin' toast. Sorry.
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RV-9A, 2011, bought flying
IO-320D1A (factory new), C/S
IFR equipped
AFS 5400/3500, G5, IFD440 navigator,
bunch of other stuff

Last edited by MacCool : 01-22-2022 at 06:49 PM.
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  #10  
Old 02-02-2022, 07:08 AM
dozewase dozewase is offline
 
Join Date: Dec 2010
Location: NH
Posts: 7
Default Battery drain

Hi Gary
I had the same problem a 4 mil amp drain with master switch off ! I also have a lithium EarthX battery which is new! After a lot of time and money traced the current draw to my Vp200 electronics breaker system. I installed a shut off covered toggle switch on my rear bulkhead with in reach off my baggage door. I turn power off post flight and on to fly. I have zero problems now With discharge!
Simple fix that works
Cheers
RS
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