Today's Message Index:
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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
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| Subject: | Re: OVP relay in B+ lead bad idea |
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.
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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
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| Subject: | Re: OVP relay in B+ lead bad idea |
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
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| Subject: | Re: OVP relay in B+ lead bad idea |
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
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