---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 05/07/23: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:44 PM - shorted AGM battery (johnbright) 2. 09:53 PM - Re: shorted AGM battery (Tim Olson) ________________________________ Message 1 _____________________________________ Time: 06:44:56 PM PST US Subject: AeroElectric-List: shorted AGM battery From: "johnbright" 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 N1921R links 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 _____________________________________ Time: 09:53:01 PM PST US Subject: Re: AeroElectric-List: shorted AGM battery From: Tim Olson 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 > N1921R links > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=510746#510746 > > > Attachments: > > http://forums.matronics.com//files/img_0199_683.png > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.