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Touring Motor Gliders Association (TMGA)
Eric Greenwell

Battery problems

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Eric Greenwell

Here's what I wrote Jim. He didn't have any ideas about why the batteries aren't lasting longer, but I'm hoping someone will have a clue.

Situation:

In Feb 2015, I discovered that one of the auxiliary (front mounted) batteries (two 12 volt, 18 AH units in parallel) had only a few AH of capacity, but the other one still had over 14 AH. The failed battery was removed.

May 31, I tested the remaining auxiliary battery, and it now has less than 2 AH, so it has also failed, and in only 3 months from the last time I tested it.

I tested the engine battery: it has 13 AH, and still starts the engine easily.

Remarks:

The two auxiliary batteries did not wear out (showing a diminishing capacity over time - the normal symptom of an aging battery), but failed catastrophically by losing most of their capacity in a few months. The engine battery, even though it's still usable, has lost 28% of it's capacity, a large loss for a 16 month old engine battery (210 hours run time) that was never deep-cycled, but used only to start the engine, and is charged during flight, and ocasionally in the hangar if it hasn't flown for a few weeks.

As a side note, I've had the same problem with the SLA batteries in my ASH 26 E (they are the sealed lead acid as they come from the battyer manufacturer, not "dry charged" like the original ones in the Phoenix): for the first 12 or so years, batteries would easily go 3 years, at which point I'd replace them preemptively; for the last 8 years, I seemed to get less and less service out them, with the last set not even lasting 1.5 years. I'm baffled about why they don't seem to hold up as well as they used.

Resolution:

Since two of the Phoenix batteries have failed catastrophically, and the remaining one is weak, I'm concerned that it will also fail catastrophically. I'd like to replace them with Odyssey batteries, but Odyssey doesn't make any in the shape of the Phoenix units. Some possibilities:

  • Find a company that makes a battery as good as the Odyssey, but in the proper size to fit the existing battery boxes (I haven't found one yet)

  • Modify or replace the boxes to fit the batteries I want to use, which might include a Lithium battery for the engine, like Jim is using

Because of timing issues with trips, etc., I've ordered a Yuasa brand battery the same size as originally supplied, and hope they build a better battery than Xtreme (the original battery brand)! I'll move the current engine battery to the auxiliary box, and recycle the failed one. This will let me fly without worries till next spring, and maybe I'll have a great idea in the meantime, or at least can make the changes during the winter, when I'm not flying so much.

All comments and suggestions welcomed!

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Gfeldman

Eric,

I guess this is pretty obvious but have you checked whether these batteries are being properly recharged in flight?

George

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Eric Greenwell
Eric,

I guess this is pretty obvious but have you checked whether these batteries are being properly recharged in flight?

George

The engine/rear battery is always charged in flight, and is not used for soaring, so it's essentially fully charged all the time.

The soaring/front batteries were sometimes charged in flight. If I used them for engine-off soaring, I would charge them with a 4 amp, 3 stage AC charger when I returned them to the hangar.

The SkyView voltmeter always shows 13.8, unless the soaring batteries are selected after engine-off soaring (and thus somewhat discharged). For that situation, the voltage will be lower (13.4-13.6) for while, rising to 13.8 after a while. I still put the charger on the soaring battery after returning to the hangar.

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edwalker

Hi, Eric -

I know it's been a while, but I got to thinking about this some more. Did you figure this out finally? Sounds very unusual.

Do you have anything plugged into your rear DC outlet like one of those USB power adapters? If your plane is like mine the rear outlet is wired as unswitched, so I have to be careful to unplug anything with even a small current drain since it can slowly discharge the battery. You mentioned charging the battery with an AC charger - do you leave on all the time or just until the battery is fully charged?

Ed

 

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Martin Stepanek

Hello dear friends!

This is a very strange situation, because in Phoenix airplanes flying in EU we don´t have such a problems at all.

For example - on 01/U15 I have the same battery since 2009 - never recharged, never removed. Durign winter time still installed in airplane and in hangar we have no heating.

But true is that we don´t use two baterries because of weight limitation.

In case you have in your Phoenix installation of two batteries - are they interconnected? Or in your system you switch battery 1 OR battery 2?

And how is solved recharging? Again - to both batteries together or separatelly depending on switch position?

Best regards!

Martin

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Eric Greenwell
On 3/20/2016 at 9:12 PM, edwalker said:

I know it's been a while, but I got to thinking about this some more. Did you figure this out finally? Sounds very unusual.

Do you have anything plugged into your rear DC outlet like one of those USB power adapters? If your plane is like mine the rear outlet is wired as unswitched, so I have to be careful to unplug anything with even a small current drain since it can slowly discharge the battery. You mentioned charging the battery with an AC charger - do you leave on all the time or just until the battery is fully charged

I have not figured it out. The replacement batteries seem OK, but I haven't tested them since installation. I'll do that in the next few days - thanks for the reminder.

I don't think I left anything in the shelf power socket that would discharge it, and I never noticed a discharged battery. Everything seemed to be normal at all times, until I did a capacity test on each battery. That's when I discovered they had lost much more than expected.

I leave the AC charger on until the battery is fully charged, then disconnect it, usually the next day or two. It's a high quality charger with the proper float voltage.

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Eric Greenwell
19 hours ago, Martin Stepanek said:

This is a very strange situation, because in Phoenix airplanes flying in EU we don´t have such a problems at all.

For example - on 01/U15 I have the same battery since 2009 - never recharged, never removed. Durign winter time still installed in airplane and in hangar we have no heating.

But true is that we don´t use two baterries because of weight limitation.

In case you have in your Phoenix installation of two batteries - are they interconnected? Or in your system you switch battery 1 OR battery 2?

And how is solved recharging? Again - to both batteries together or separatelly depending on switch position?

 

The engine battery was in fair condition and still started the engine adequately; the main problem was the auxiliary battery used for soaring. It was in poor condition.

The engine battery and soaring battery are connected with four position switch that selects the following: 1) engine battery   2) soaring battery   3) engine and soaring battery in parallel  4) OFF - all batteries disconnected.

The batteries can be charged in flight by setting the switch to the desired battery (or the two in parallel). The switch is used the same way on the ground, but the AC charger is connected to the power socket on the right side of the panel (the Master switch must also be turned on). Normally, the engine battery is fully charged, since it is used only for starting. The soaring battery usually needs some charging after a soaring flight.

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Martin Stepanek

Very good explanation dear friend! Thank you... :-)

It means that is done well. We normaly install one battery and second battery box (not the second battery).

Definitelly don´t use parallel connection - it causes only that better battery is "sponzoring" the worse one.

Or... sounds promissing to use new LiFePO systems... Weight is better so you can have one battery with large capacity.

I know that sounds good to have "spare" battery, however as you wrote - than is necessary to keep on mind to recharge it (or at least to check it) after longer soaring flight.

Best regards!

Martin

 

 

 

 

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