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1. 06:44 PM - shorted AGM battery (johnbright)
2. 09:53 PM - Re: shorted AGM battery (Tim Olson)
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| Subject: | shorted AGM battery |
In 2019 there was a homebuilt tractor configuration two-place SBS aircraft with
an EFI system that had an off-field landing. Nothing got bent, nobody got hurt,
failed battery replaced, AC took off from the landing site.
Hearsay had the problem as a shorted Odyssey AGM battery. But, Bob Nuckolls says:
"We used to see the occasional shorted cell in flooded batteries. This could cause
a 12 volt battery to become a 10 volt battery. Remaining good cells then suffered
overcharging.
RG batteries don't do this."
Saturday May 6, 2023 I met the pilot at a grass strip fly-in in Suffolk, VA. I've
been wanting to ask him if it was the battery itself or something external
to the battery across the terminals. He says Odyssey AGM battery internal short,
battery case swelled, photo attached.
He saw the voltage drop to 13-1/2 and thought alternator problem, then it fell
to 12-1/2 and he thought alternator offline, then the voltage continued to fall
and when it got to 7 the engine stopped.
The battery box, located aft of the passenger compartment, was larger than the
battery and some type of foam was used to fill the space.
The battery has been discarded so no autopsy possible.
Pilot says:
"I would estimate 1 year and 50 flights, ~100 hours on that battery.
Belt driven Plane Power alternator.
Two batteries in parallel.
Both batteries could be used to start the plane or power the main bus (this was
before the diode was installed). I don't have a drawing of it."
He says there was some sort of contactor arrangement whereby the batteries could
be paralled or not, batteries in parallel as the voltage fell. He said he paralleled
the batteries in flight when the EFI voltage began to fall.
This was a short local photo flight.
No electrical power schematic available.
My first theory is battery was depleted at takeoff and overheated due to thermal
insulation value of the foam around it combined with high capacity alternator.
I'm wondering what Bob and others think.
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
<a href="https://docs.google.com/document/d/1YOtPiA3AdUsQEYR4nodBESNAo21rxdnx4pFs7VxXfuI/edit"
target="_blank">N1921R links</a>
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=510746#510746
Attachments:
http://forums.matronics.com//files/img_0199_683.png
Message 2
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| Subject: | Re: shorted AGM battery |
Is that for sure an odyssey? I haven't ever seen an odyssey that looked
like that, and I don't think they even have that
big white sticker on them. The individual cell caps aren't something
I've ever seen on an Odyssey either.
That said, I know Odyssey makes some battery types that I haven't ever
physically seen, but this one
just doesn't have any of the characteristics that I've seen before in
data sheets.
Tim
On 5/7/2023 8:44 PM, johnbright wrote:
>
> In 2019 there was a homebuilt tractor configuration two-place SBS aircraft with
an EFI system that had an off-field landing. Nothing got bent, nobody got hurt,
failed battery replaced, AC took off from the landing site.
>
> Hearsay had the problem as a shorted Odyssey AGM battery. But, Bob Nuckolls says:
>
> "We used to see the occasional shorted cell in flooded batteries. This could
cause a 12 volt battery to become a 10 volt battery. Remaining good cells then
suffered overcharging.
>
> RG batteries don't do this."
>
> Saturday May 6, 2023 I met the pilot at a grass strip fly-in in Suffolk, VA.
I've been wanting to ask him if it was the battery itself or something external
to the battery across the terminals. He says Odyssey AGM battery internal short,
battery case swelled, photo attached.
>
> He saw the voltage drop to 13-1/2 and thought alternator problem, then it fell
to 12-1/2 and he thought alternator offline, then the voltage continued to fall
and when it got to 7 the engine stopped.
>
> The battery box, located aft of the passenger compartment, was larger than the
battery and some type of foam was used to fill the space.
>
> The battery has been discarded so no autopsy possible.
>
> Pilot says:
>
> "I would estimate 1 year and 50 flights, ~100 hours on that battery.
>
> Belt driven Plane Power alternator.
> Two batteries in parallel.
> Both batteries could be used to start the plane or power the main bus (this was
before the diode was installed). I don't have a drawing of it."
>
> He says there was some sort of contactor arrangement whereby the batteries could
be paralled or not, batteries in parallel as the voltage fell. He said he
paralleled the batteries in flight when the EFI voltage began to fall.
>
> This was a short local photo flight.
>
> No electrical power schematic available.
>
> My first theory is battery was depleted at takeoff and overheated due to thermal
insulation value of the foam around it combined with high capacity alternator.
>
> I'm wondering what Bob and others think.
>
> --------
> John Bright, RV-6A, at FWF, O-360
> Z-101 single batt dual alt SDS EM-5-F.
> john_s_bright@yahoo.com, Newport News, Va
> <a href="https://docs.google.com/document/d/1YOtPiA3AdUsQEYR4nodBESNAo21rxdnx4pFs7VxXfuI/edit"
target="_blank">N1921R links</a>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=510746#510746
>
>
> Attachments:
>
> http://forums.matronics.com//files/img_0199_683.png
>
>
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