---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 11/14/24: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:16 PM - Re: OVP relay in B+ lead bad idea (user9253) 2. 06:34 PM - Re: Re: OVP relay in B+ lead bad idea (Finn Lassen) 3. 07:27 PM - Re: OVP relay in B+ lead bad idea (user9253) ________________________________ Message 1 _____________________________________ Time: 04:16:14 PM PST US Subject: AeroElectric-List: Re: OVP relay in B+ lead bad idea From: "user9253" I also had a PC680 battery fail open due to a broken internal weld. You can read about it here: http://forums.matronics.com/viewtopic.php?t=16762906 Luckily my Rotax 912uls does not depend on the aircraft electrical system. So the engine kept running fine. . Below is a circuit with an aux battery for the engine bus. Suggestions welcome. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=514520#514520 Attachments: http://forums.matronics.com//files/aux_engine_battery_460.png ________________________________ Message 2 _____________________________________ Time: 06:34:27 PM PST US Subject: Re: AeroElectric-List: Re: OVP relay in B+ lead bad idea From: Finn Lassen Fascinating! Mine is a Power Sport YTX20L-BS but symptoms very similar. I managed to charge it up to 13V over night. But when lightly loaded with an engine monitor it dropped to ~5V. Perhaps the 5V is just where the EM voltage regulator cuts off. I'll try with a landing light. I looked at the thread you referenced. Did Bob ever do an autopsy on your PC680? I don't really like relays -- prefer switches if reliable. I'm thinking a backup battery on the cockpit side of the firewall (the PC680 in a metal case has a temp limit of 140F and I measured as much a 190F in the alternator -- granted, the alternator mounted on the engine -- significant thermal transfer from engine to alternator housing). Currently my engine bus is always live (connected to battery via fuseable link). I'm thinking of inserting a DPDT switch between the main battery and engine bus. In normal operation engine bus would be connected to main battery and the second pole to a diode from alternator/main battery to charge the backup battery. When throwing the switch that diode would be disconnected and the engine bus connected to only the backup battery. Of course that makes that switch a single point of failure. The way I see it I want to protect against: 1) Overvoltage from alternator reaching battery, main and engine bus. 2) Alternator short to ground shorting battery, main and engine bus. 3) Dead main battery and/or alternator not affecting back-up battery and engine bus. Obviously also need to be able to shred non-essential loads to extend flight time. There a backup battery would extend running time in case of failed alternator and good main battery. Finn On 11/14/2024 7:15 PM, user9253 wrote: > > I also had a PC680 battery fail open due to a broken internal weld. You can read about it here: > http://forums.matronics.com/viewtopic.php?t=16762906 > Luckily my Rotax 912uls does not depend on the aircraft electrical system. > So the engine kept running fine. > . > Below is a circuit with an aux battery for the engine bus. Suggestions welcome. > > -------- > Joe Gores > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=514520#514520 > > > Attachments: > > http://forums.matronics.com//files/aux_engine_battery_460.png > > ________________________________ Message 3 _____________________________________ Time: 07:27:26 PM PST US Subject: AeroElectric-List: Re: OVP relay in B+ lead bad idea From: "user9253" Yes, Bob performed an autopsy. http://forum.matronics.com/viewtopic.php?p=460530 .. http://www.aeroelectric.com/Pictures/Battery_Failures/PC680_12SEP2016/11_Inter-cellconnectorweldfailure.jpg -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=514522#514522 ------------------------------------------------------------------------------------- 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.