humptybump
Well Known Member
Update: I have never said who the battery vendor is. After a good open discussion of several days, a moderator took it upon themselves to change the title of my thread to add “(Not EarthX)”. I did not request that change.
On a recent flight, on a cruise descent, while about 30 minutes from landing, my engine monitor gave an over voltage warning.
A brief diagnostics determined it wasn’t something I’d resolve in flight.
Background: My plane has one alternator, one main battery, and one “minimum essentials” backup battery. The backup battery is “dumb” while the main battery is newer - (a recent replacement) - and has an integrated battery management system (BMS).
No worries I thought. I’ll switch off the alternator and the main battery is more than enough for the last 30 minutes with plenty of power to spare.
Oops.
It appears the undocumented BMS behavior in my situation is to disconnect itself and shutdown for some unknown amount of time.
I landed with my backup systems without incident.
The moral? My redundant electrical system isn’t as redundant as I had thought. I had assumed an alternator failure would leave me with main and backup batteries. The reality is some basic failure scenarios could immediately remove two sources of power, not just one.
If you have a BMS associated with your battery it’s a good idea to know it’s response to all of the situations it’s design to protect.
On a recent flight, on a cruise descent, while about 30 minutes from landing, my engine monitor gave an over voltage warning.
A brief diagnostics determined it wasn’t something I’d resolve in flight.
Background: My plane has one alternator, one main battery, and one “minimum essentials” backup battery. The backup battery is “dumb” while the main battery is newer - (a recent replacement) - and has an integrated battery management system (BMS).
No worries I thought. I’ll switch off the alternator and the main battery is more than enough for the last 30 minutes with plenty of power to spare.
Oops.
It appears the undocumented BMS behavior in my situation is to disconnect itself and shutdown for some unknown amount of time.
I landed with my backup systems without incident.
The moral? My redundant electrical system isn’t as redundant as I had thought. I had assumed an alternator failure would leave me with main and backup batteries. The reality is some basic failure scenarios could immediately remove two sources of power, not just one.
If you have a BMS associated with your battery it’s a good idea to know it’s response to all of the situations it’s design to protect.
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