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Finding battery discharged, again.

NinerBikes

Well Known Member
Friend of mine owns a 2016 RV-12 he built... N836BL, and he's having difficulty with the battery, quite new, being found in a state of discharge.

Today's voltage read 11.7V, battery was bought new at Aircraft Spruce in May, 2019.

Any suggestions on where to look for phantom drain of this battery such that it goes dead? Any relays?

We believe, currently, that the electrical problem may be intermittent.


Are 20-25 minute flights enough 1x a week for the voltage regulator to go into full 14.4V charge rates in that amount of time, or are longer flights necessary? Is a different Ducati brand VR worth looking into?
 
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While monitoring for parasitic drain at the battery (GOOGLE: Parasitic Drain) deactivate individual circuits by pulling individual fuses to identify suspect drain.

You could also disconnect the battery (remove negative terminal cable) after a flight and reattach the cable at the next flight. If the battery is still strong, it is likely a parasitic drain issue and not a weak battery or defective charging system.

In my experience, those short flights should be sufficient for a stock Odyssey PC-680/Ducati RR system to substantially recharge. Longer flights would likely be better for more thorough battery charging. I have found that frequent flying does wonders for the battery and IMHO trickle chargers are to be avoided.
 
A cheap DVM with a DC current range can show you if you have any drain on the battery while the system is shut off.
 
Many Ducati voltage regulators put out less than 14 volts. My Ducati put out
13.8 volts. A friend's Ducati puts out 13.7 volts. I now have a John Deere
voltage regulator that puts out 14.1 when the RPM is above 4000.
If your friend's 20 minute flight includes 10 minutes of warm up and taxiing and
another 5 minutes of closed throttle for landing and taxiing, then that does not
leave very much time to recharge the battery.
Usually a battery maintainer is not recommended. But there are exceptions.
 
Also check for anything (like a USB power plug) in the 12V power socket. The socket is wired to the battery, not the master, so if you have a USB power supply plugged in it will suck current from the battery even with the master off.

I moved mine to the switched side of the master, took all of 10 minutes while we had the top cowl off.
 
Also check for anything (like a USB power plug) in the 12V power socket. The socket is wired to the battery, not the master, so if you have a USB power supply plugged in it will suck current from the battery even with the master off.


I wouldn't necessarily say that the socket *IS* wired to the battery, not the master.. But rather that it *MIGHT* be. Good suggestion though.
 
Odyssey Technical Manual, ninth Ed. 2016 (page 16)

Chart shows for deep cycle operations,...charging at 14.7 volts more than doubles the life of the battery, compared to 14.2 volts....

....wonder where 13.7 volts would lie on the graph, ....(and how far the parasitic load is draining the battery)
 
Odyssey TM on parasitic load

Regardless of the application, it is important to make sure your battery does not have a parasitic load; if there is a slow drain, connect the battery to a float (trickle) charger that puts out between 13.5V and 13.8V at the battery terminals. Physically disconnecting one of the battery cables is an alternate method to eliminate the drain.
 
Stay alive circuits

Some avionics have a stay alive circuit wired directly to the battery, or to seperate fuse block which is then wired directly to the battery. Dynon D-10 for example. Or maybe a clock.
 
I wouldn't necessarily say that the socket *IS* wired to the battery, not the master.. But rather that it *MIGHT* be. Good suggestion though.
Ah -- yeah, I see they changed that a couple years after mine was built.
 
I think I would disconnect the cables and measure volts then wait a week and measure volts again before I looked any deeper.

I drive a company vehicle and I have a MX manager who loves a bargain so when my company truck needed a battery he went to Interstate and bought a battery off their scratch and dent rack. "Been using them for years, just as good as the full price batteries but cost half as much..."

Then I started having to put a charger on it to get it going on Monday morning after it sat all weekend. We sent it into the shop and they started disconnecting things to find the source of the drain.

The whole while I was saying not for nothing but it worked fine and the battery was the last thing we changed a few months ago...

No, no, its got to be something else, lets disconnect the trailer brake box... You've got a backup camera that wasn't original, lets disconnect that... Maybe its the radio, lets pull that out...

Yeah but it worked fine and we changed the battery a few months back and now there's a problem, can't possibly be the battery...

So I parked it and disconnected the battery cables. Waited a few days, connected the cables back up and bingo, dead battery.

Scratch and dent batteries end up on the scratch and dent rack for a reason. Sometimes scratch and dent batteries don't end up on the scratch and dent rack.

The battery was recently changed. I say charge it up then disconnect it and come back in a week and see what you get before you go looking any deeper.
 
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I installed a USB charger socket in place of the cigarette lighter. My mini iPad remains connected to the charger all the time. The socket itself pulls about 10mA and is a constant draw on the battery. To counter this I use an Odyssey 6 Amp Portable Charger which I leave connected to the airplane all the time in the hanger.

The Odyssey charger is not a float or trickle charger – it is designed specifically for Absorbed Glass Mat (AGM) and flooded lead acid batteries. The charger maintains voltage only as needed, so when the battery is fully charged there is no current flow. The charger has an automatic cycle that disulfates the battery once/month. This cycle also happens every time the charger is reconnected after flying.

I’ve been doing this for two years and so far everything is hunky-dory.
 
Also check for anything (like a USB power plug) in the 12V power socket. The socket is wired to the battery, not the master, so if you have a USB power supply plugged in it will suck current from the battery even with the master off.

I moved mine to the switched side of the master, took all of 10 minutes while we had the top cowl off.

So it would be possible to recharge through the 12v power socket, instead of having to open up the cowling every time pulling the piano hinge pins?
 
Battery is pulled and recharged.... will take a voltage reading next week before we reinstall it and go out flying, weather and temps permitting.

Wondering if being subject to all that heat under the cowling while after a hot shut down is causing the discharge. It's a 15 Ah AGM battery under there, sitting at the top of the cowling up against the firewall.
 
Search ?battery rejuvenation? in prior posts

Prior to declaring victory, with one charge,....
Recommend you try the slow discharge, then charging at recommended voltage and amperage,..... then doing it again and again (longer each time) till it gives rated capacity,...or you find it is damaged,....
 
IMHO, heat under the cowl is normally not an issue for the battery's health*. Next time you have the top cowl removed (takes less than two minutes) install a pigtail set of wires from the battery terminals to a suitable adapter plug that is compatible with your charger. You can then open the oil access door pull out the lead and easily plug in a charger, VOM, etc.

*ps -- It helps to open the oil access door after every flight to vent the heat within the cowling. This is good for the engine's electronics, hoses, wiring, and cowling fiberglass.
 
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IMHO, heat under the cowl is normally not an issue for the battery's health*. Next time you have the top cowl removed (takes less than two minutes) install a pigtail set of wires from the battery terminals to a suitable adapter plug that is compatible with your charger. You can then open the oil access door pull out the lead and easily plug in a charger, VOM, etc.

*ps -- It helps to open the oil access door after every flight to vent the heat within the cowling. This is good for the engine's electronics, hoses, wiring, and cowling fiberglass.

I do the PS oil access door at every stop to let the heat out. Always button it back up after burping the engine and checking the oil level as pre flight check too. Don't want that flapping around on run up or take off.
 
Many Ducati voltage regulators put out less than 14 volts. My Ducati put out
13.8 volts. A friend's Ducati puts out 13.7 volts. I now have a John Deere
voltage regulator that puts out 14.1 when the RPM is above 4000.
If your friend's 20 minute flight includes 10 minutes of warm up and taxiing and
another 5 minutes of closed throttle for landing and taxiing, then that does not
leave very much time to recharge the battery.
Usually a battery maintainer is not recommended. But there are exceptions.

20 minutes is as estimated on Flightaware. Does not include start up, taxi, run up, waiting behind the hold short line to take off, or take off and turn. Doesn't really include time until about 15 to 1700 AGL or about 2700 ft elev, when we finally show up on ADSB and Flightaware starts recording time in flight. We also dissappear below about 3000 feet at KSZP, so add in 4 or 5 minutes landing too. Probably close to 35 minute or more of run time on the Hobbs.
 
Going to pull my clamp inductance measurement device out of the Rec Vehicle that measures current flow, and start pulling fuses, and see what we get, since I bought it and used it to measure current draw on every single circuit in the rig, as well as calculate total current draw in a 24 hour period, before the solar panel and day break kicked in to charge things back up from overnight.

Thanks all, for the suggestions.
 
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It's a bit early, but I think this one might have a dead cell, or an internal shorted cell inside the battery. Voltage was:

12.89 on 9-2 at 00:00z, after charging.

12.79 on 9-3

12.68 on 9-4

12.61 on 9-5 in the early AM

It was 12.85 when brand new. No telling how long it had been on the shelf.

I don't think we're going to be able to fly this Sunday, judging by the way the voltage keeps dropping. A weekday flight to Corona might be in order to visit Aircraft Spruce again.
 
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Did you follow the suggestion to look for a parasitic load? Undo one battery connection, and put an ammeter in series. You?re looking for a drain of 100 ma or less - your inductance device probably can?t go that low.
 
So the battery voltage has been dropping 0.1 volts per day for two days.
Is that with the battery connected to the aircraft electrical system?
Or is at least one battery terminal disconnected?
The battery still has 90 percent of its energy at 12.7 volts. There is something
wrong with the battery if the voltage continues to drop without its leads being connected.
But if the battery voltage remains at 12.7 with cables disconnected, I would not be concerned.
 
this shouldn't be so difficult. pull the battery and see if it drains. if it does you need a new battery. if it doesn't then you have a parasite load in the system with the master off. at this point that's all i know but guys with more elect. knowledge could say if this drain could be confirmed as easily as connecting an ohm meter to the battery cables of your plane with the masters off.
 
So the battery voltage has been dropping 0.1 volts per day for two days.
Is that with the battery connected to the aircraft electrical system?
Or is at least one battery terminal disconnected?
The battery still has 90 percent of its energy at 12.7 volts. There is something
wrong with the battery if the voltage continues to drop without its leads being connected.
But if the battery voltage remains at 12.7 with cables disconnected, I would not be concerned.

Completely disconnected and removed, sitting in the garage at home on the work bench after being charged up Saturday afternoon. Will wait on a reading today.

AGM batteries generally sit at about 12.81 to 12.87 fully charged, depending on ambient air temperatures, after the surface charge from a fresh recharge bleeds off.

Does the emergency transponder stay charging despite power off on these RV-12s? Or the Dynon Skyview backup battery?
 
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Did you follow the suggestion to look for a parasitic load? Undo one battery connection, and put an ammeter in series. You?re looking for a drain of 100 ma or less - your inductance device probably can?t go that low.

Waiting for my friend to put the battery back in the RV-12 before we can do that.
 
this shouldn't be so difficult. pull the battery and see if it drains. if it does you need a new battery. if it doesn't then you have a parasite load in the system with the master off. at this point that's all i know but guys with more elect. knowledge could say if this drain could be confirmed as easily as connecting an ohm meter to the battery cables of your plane with the masters off.

I have an RC watt meter, which I use with my portable ham radios, that can go in line, that can certainly go that low.
 
12.61V on Friday morning, sitting in the shop, completely disconnected from the plane.

Don't think the battery made it more that 3 months, flying 1x per week. Back to Aircraft Spruce.
 
Odyssey battery below 12 volts

This same thing happened to my Odyssey PC680 this week after only 7 months in service. Odyssey company technical support was very helpful and said they would send me a new one. They said it sounds like a bad cell. Symptom was that it dropped to 11.5 volts over night and after a 30 minute flight with alternator voltage showed 14.5 volts it didn?t charge and still showed only 11.9 volts. With just the Dynon screen on I watched the voltage drop from 11.9 to 10.7 in about a minute. I don?t have a charger for AGM battery but I also don?t have any reason to think there is drain. I don?t know of an event that caused the low voltage to show up. I have just finished phase 1 testing and completed a couple long cross countries which is unusual but how would that cause the voltage loss? I have a pig tail cable running from battery thru firewall to cockpit so that I can jump start it from the cockpit and that works using another battery.

If anyone knows any reasons or ways to make a bad cell please share. Thanks.
 
My battery suddenly stopped charging, and my mechanic has done everything suggested in this RV-12 Forum and elsewhere for this malady, including replacing the rectifier/regulator, grounding the regulator with a wire (in addition to cleaning the contact the regulator housing makes with the firewall), testing the stator, checking and reattaching the wires leading to and from the regulator. None of those things fixed the problem. I'm still getting amp readings between -4 amps and -10 amps (depending on which equipment is turned on), even when taxiing at 2500 and higher rpms. The battery voltage also drops, and is now down at the low end of 11 volts.

I'm beginning to suspect my system has a parasitic drain in it somewhere.

Finally, my question:

I have pigtail wires attached to the battery (about 6 inches long) so I can charge the battery through the oil inspection door without having to remove the cowl. The charger attaches to the wires via a plastic PowerPole connector that, when not in use, is protected by a cap. The cap is tight, so I've jiggled it and the wires a fair amount every time I use the pigtail wires. (I use them whenever I turn on the Dynon displays while the engine is off, for example to update databases and learn new-to-me Dynon features.)

Is it possible that the pigtail wires themselves are a parasitic draw on the battery, as a result of damage I did while jiggling the cap?
 
I wasn't aware that Anderson Powerpole offered a protective cover. This presents no problem.

I made an Anderson Powerpole pigtail for my battery and connect an Odyssey OBC-6A charger 24/7 when airplane is in the hanger. The Odyssey charger is not a trickle or float charger - it charges only when required - otherwise it sits idle. Main reason I use it is that it has a de-sulfate cycle each time it's powered up. I've been doing this for three years and battery is hunky-dory.

How old is your battery?
What battery charger are you using?

 
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Piper J3:

I have three Odyssey PC680 batteries. One came with the plane (an RV-12 ELSA that I bought from the builder) and two that were given to me by a friend who had them in his 24-volt system plane until he replaced them with two lighter batteries. All three are 2018 vintage batteries, and seem to be in good condition.

I didn't think the PowerPole cap itself was the problem. I wonder whether jiggling the pigtail wires while prying the cap off may have damaged the pigtail wires in some way, and thereby turned the pigtail into a parasitic draw on the battery's power.

It sounds like your pigtail wires are in good condition. When I first got my plane, with the pigtails installed, my battery accepted a charge too. It stopped accepting a charge, and my amp readings went to negative, quite suddenly. Everything was fine on a flight from my home airport to another airport not far away. The plane was on the ground, in the shade, for three hours, in my sight at all times. When I started the plane three hours later, the amps were negative and didn't turn positive, even during a 4000 rpm runup.

My stator checks out as fine; it's producing 15+ volts of AC current. My Ducati rectifier/regulator was replaced by my mechanic with a brand new one (actually two new ones, just to be certain the first wasn't defective right out of the box). And yet, I still get negative amps and declining voltage. Hence, I'm hunting for a "parasite."

When I had my plane in a hangar, I used a Schumacher SE-82-6 battery charger while running the Dynon with the engine off. When I moved my plane to a tie-down area, I used two of the Odyssey batteries, connected parallel, in place of the charger.
 
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Connecting spare batteries in parallel with the aircraft battery will NOT recharge the aircraft battery.
_With the master switch OFF, disconnect the negative battery cable. Now measure the voltage
between that negative cable and the negative battery post. It should be zero volts. If not, there is
a parasitic drain. Measure parasitic drain with an ammeter. When done, set meter to volts.
_Use a spare male faston to test the gripping strength of each female regulator terminal.
_Measure continuity between the two big yellow generator wires and ground. There should be infinite ohms.
_Tug on each regulator terminal wire to be sure each is securely crimped.
_With the battery negative cable reconnected, and with the master switch turned on, connect a voltmeter
black lead to the battery negative terminal. Measure the regulator voltage on terminals B+, R, and C. Are
all voltages equal to battery voltage?
_Be careful not to short out regulator female terminal C. Doing so could require an expensive repair.
 
We had a situation last week where we were flying at 5200 rpms , showing 13.3 to 13.7V and -4 to -8 or -9 amps, and I started pulling fuses while Bob was flying, trying to isolate the problem. No fuse pulled reduced the current draw.

Pulling the fuse for the EFIS started the 30 second shutdown process.

Not sure, but we are thinking with all that fuse pulling and no solution... Perhaps it might be the Dynon1000 that's causing the current draw being shown, but, there's been no smell of electrical shorts yet. Perhaps it's faulty readings or an electrical shunt giving off false numbers to the Dynon 1000 touch?

This was a one flight occurrence. It did not demonstrate this behavior on the 22 minute flight back.
 
We had a situation last week where we were flying at 5200 rpms , showing 13.3 to 13.7V and -4 to -8 or -9 amps, and I started pulling fuses while Bob was flying, trying to isolate the problem. No fuse pulled reduced the current draw.

Pulling the fuse for the EFIS started the 30 second shutdown process.

Not sure, but we are thinking with all that fuse pulling and no solution... Perhaps it might be the Dynon1000 that's causing the current draw being shown, but, there's been no smell of electrical shorts yet. Perhaps it's faulty readings or an electrical shunt giving off false numbers to the Dynon 1000 touch?

This was a one flight occurrence. It did not demonstrate this behavior on the 22 minute flight back.

My mechanic now suspects my Dynon HDX, too. The HDX readings aren't false, though. He checked my battery with his handheld multimeter, and it showed the same amps and volts as the Dynon. He wonders, though, whether the Dynon is sucking more electricity from the battery than it should or has in the past.
 
NinerBikes,
Since the voltage is normal, the ammeter display is erroneous for some reason.

The voltage is normal for something drawing a lot of current and being consistent about doing it. 13.3V and 8 to 9 amps in the negative, the alternator can't keep up with the power draw, and the battery is going down. 13.7 to 13.8V and still negative amps showing, and battery being drawn down.

Normally at start up, we will immediately see positive amps at +8 or +9 charging, and it reduces to +1 to +2 and 14.1 or 14.2V by the time we are taxied down, and oil temp is up to temps to do run up tests of the ignition systems.

Since the gearbox wear episodes read about here, with worn dogs, and Rotax gearbox parts being waaaay more expensive than brake pads or rotors, Bob has been keeping the plane at 2500 rpm and using more brakes, which definitely keeps the voltage and amps up in the positive for the battery. Plane is now almost 190 hours.

Landing patterns show a marked negative amperage charge rate showing, so we've modified shut down procedure with a 2500 rpm run up at the hangar until amps drop down to a +1 amp charge rate, then chop the throttle, then shut off the ignitions.
 
Electrical loads always draw current from the source with the highest
voltage. If electrical system voltage is 13.3 or higher, then it is impossible for
the battery to be supplying any current whatsoever because its voltage is
not that high. Loads will draw current only from the alternator because it
has higher voltage than the battery. If the alternator can not keep up with
the demand, then system voltage will drop until it reaches battery voltage,
about 13 volts. Then both battery and alternator will supply current.
-
Check the shunt terminal connections.
 
This is a late reply.

Been using the same new battery now for about 7 or 8 months. Problem was a combination of two items, a bad batttery, not desulphate charging fully, regularly, and a bad Ducati Voltage regulator.

AGM battery chemistry really requires that it be stored when not in use, with a completely full top charge, to prevent sulphation of the plates inside the battery. Taking good care of your AGM battery properly requires a full complete charge on a battery charger every 6 months and would be a good idea for proper maintentance.

Phantom parasitic drain was not a problem in this plane.

With the number of people complaining about short battery life with the Odyssey batteries in all of the Van model lines, I'd suggest you take it up with whoever sourced you your battery.

Save your receipts, you'll need them.

Or find a different brand of battery.
 
My plane lives outside. I just ordered a Suner weatherproof 12W smart solar charger from Amazon to keep my 32 amp/hr AGM battery fully charged. ($60 + shipping.) I plan to leave it plugged into one of my cigarette lighter plugs at home and on cross countries. John
 
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