Low battery, is only a year old

I don't know the chemistry of it, but I've seen bad lead acid batteries take a "surface charge", where they'll hold 12.6V for a tiny bit of time, then with a really light load pop down to much less than that and stay there. I don't know if that's damage to the plates or something else.
 
Any "battery charger" you use on a lead-acid battery should include desulfation.
There are a number of specific aviation-aimed battery minders and and automotive versions which include desulfation.

If my Warrior is not flying, the battery is on the tender.
 
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I’m a big fan of periodic time on the maintainer or battery tender. I put my plane on every few months or so, whether it needs it or not.

He shall remain nameless, never uses a tender, short flights. Him & a buddy flew to breakfast, afterwards, no start. He got tangled up with maintenance, left the plane, $500+ later, had a new battery. Some like to learn the hard way.
 
Most chargers will kill a battery quickly if you are not careful.

The Battery Minder (aircraft and non-aircraft) and Battery Tender (mainly non-aircraft) are designed to take care of the battery and not damage it. In fact, they can even help a marginal battery come back from nearly dead (maybe).

I have seen reports of people using a Battery Tender on their aircraft with 7 - 8 YEARS on one battery.

I have a collector car on a Battery Tender, that has had the same battery for almost 15 years.
 
I have had very good luck restoring a sulfated 12V lead acid motorcycle battery using a pulse de-sulfator. Years back there was one sold by EAA Ch 79 for less than $25. It was probably just a chapter fund raiser. It was simply a kit of components with a small circuit board that when connected across the subject battery, would current pulse it with a high frequency (many KHz) current. Using an oscilloscope, after many days of operation, the reflected dynamic battery voltage drop (technically the battery internal impedance) due to this VHF cyclic load would be substantially reduced, and the battery would once again take a charge.

EAA Ch 79 apparently no longer markets this kit, but there are other de-sulphators on Amazon.
 
Battery Minder and Battery Tender have de-sulfation built in.
 
nrpetersen said:
Some versions may, but it is not obvious that they all do. Earlier Battery Tender Jrs, while excellent battery maintainers for example, don't.
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I’ve never liked the Battery Tender brand chargers/maintainers. Perhaps this is why…

I’ve always had good results with the Battery Minder products, which I believe all have a desulfate feature in them.
 
Funny, I have only one Battery Minder and several Battery Tenders. But Battery Tender does not make an aircraft version, so I will end up with a second Battery Minder.

My other one is a small one used to keep my portable generator battery charged.

I was not thinking of the Jr version. I have a couple of the 1.5 amps and a couple of the 6 amp Battery Tenders.
 
So I don’t think it’s the battery. Today I went up and suddenly the load meter went to 0. I thought that it was just not needing the alternator. On my G5 I had a warning that the data bus had a hardware fault. I didn’t put 2 and 2 together, but knew something was wrong. Btw, I bought a little cigarette lighter usb with voltage and it was only reading 11.5, which was what it was reading prior to the load meter going to 0.

I was heading up to my mechanic anyway and so I kept flying and the voltage in the USB kept dropping. Obviously the alternator or something else had failed as I was running just on battery.

He checked the battery and it was nearly dead. We recharged it and ordered a new alternator. I started home with enough charge to get there and 5 min into the flight, the load meter jumped up. I landed and the USB was showing 11.3V. There was no data bus message on the way back.

So, I know it may be that the alternator is fine (but it hasn’t shown 14v on the USB ever) and it may be something else, but I have no confidence in it. It could be a shorted wire somewhere else, I suppose.

So, I’ll see on Friday when I go up to replace it


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Your bus voltage ( cigar lighter voltmeter ) should show about 14 volts with your engine running at say 1500 rpms. If not, either your voltage regulator or generator/alternator has an issue.

I keep one of those digital voltmeters in my toolbox...very handy gadget.

Good luck.
 
Roger Wyatt said:
So I don’t think it’s the battery. Today I went up and suddenly the load meter went to 0. I thought that it was just not needing the alternator. On my G5 I had a warning that the data bus had a hardware fault. I didn’t put 2 and 2 together, but knew something was wrong. Btw, I bought a little cigarette lighter usb with voltage and it was only reading 11.5, which was what it was reading prior to the load meter going to 0.

I was heading up to my mechanic anyway and so I kept flying and the voltage in the USB kept dropping. Obviously the alternator or something else had failed as I was running just on battery.

He checked the battery and it was nearly dead. We recharged it and ordered a new alternator. I started home with enough charge to get there and 5 min into the flight, the load meter jumped up. I landed and the USB was showing 11.3V. There was no data bus message on the way back.

So, I know it may be that the alternator is fine (but it hasn’t shown 14v on the USB ever) and it may be something else, but I have no confidence in it. It could be a shorted wire somewhere else, I suppose.

So, I’ll see on Friday when I go up to replace it


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Too bad the mechanic didn't look around at stuff a little closer before ordering a new alternator. This might turn into the usual replace-parts-until-the-problem-goes-away circus. He could have checked for a shorted alternator diode just by using an ohmmeter, and with the same instrument, checked for failed alternator brushes. Like a doctor, rule out the most common stuff first, then start looking deeper.
 
Had a problem like this in my Warrior. Turned out to be a bad ground connection to the voltage regulator.
 
What troubleshooting did the mechanic base their determination the alternator was at fault?
If they can't tell you that, find another mechanic.

As others have suggested, the intermittent and sudden onset/reversal of symptoms makes me suspect something simple, loose, and inexpensive to fix. But it will take some time to investigate.
 
He was trying to get me home and then be prepared in case it is the alternator. He intends to go through looking for bad connections or something else before installing the new alternator.


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Battery tender is the worst thing you can do. Doo not leave it soon 24/7. at the most use a timer to only go on for 20 min a day.
 
1) Is the alternator belt driven? If so, it could be as simple as a loose belt. I had this happen in a Tiger I was renting.

2) A Battery Tender or Battery Minder (proper names, NOT generic brands) are fine to leave on all the time. I have a Battery Tender that has been on my collector car for about 10 years and the battery is fine. The Battery Minder on my generator has been on for around 20 years.

Only Battery Minder makes aviation specific models, which should be used for aircraft batteries, as they are not the same as car batteries.
 
Rico Burgos said:
Battery tender is the worst thing you can do. Doo not leave it soon 24/7. at the most use a timer to only go on for 20 min a day.
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Why?

I've had my Concorde on a battery tender for about 8 years. Still going strong. You need the correct, smart tender with desulfation.
 
And the culprit was …. Alternator. After tests we replaced it and the new unit was putting out amps and voltage correctly. Confirmed on the way home when my autopilot was working rock solid. The Altitude hold would never work right. Thought it was a servo. With the new alternator putting out proper amps AND voltage, it held perfectly.

So, while I wish it was something else, I’m happy to have it fixed. We also found some really poor workmanship on some sheet metal. A piece was added that was really interfering. We removed the extra piece and found it had been rubbing the alternator pulley.

It was a lot more work than expected, but worth it. I know it’s done right because I was helping. We cleaned up some crappy wiring on the landing light. All in all, it was money and time well spent.

Now I can complain that 68 cherokees don’t have a split cowling and you have to remove the prop to access the front of the engine. What a drag!


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Glad you got it fixed! And cool that you have a working autopilot, too. I've flown an Archer with one, and it just makes things more pleasant sometimes.
 
Albany Tom said:
Glad you got it fixed! And cool that you have a working autopilot, too. I've flown an Archer with one, and it just makes things more pleasant sometimes.
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It is. Took her up tonight for an hour and she worked perfectly. Such a joy when doing cross country flights.


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