Back up battery check

Tim Fitz

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Dec 25, 2019
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31
Did my back up battery check on 1 May of this year (2021). Today when I started up, I had a message that my back up battery test was needed. WTF? Thought this was a yearly check? Short of doing another test, how do I get rid of this?
 

Tim Fitz

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Dec 25, 2019
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Work around would be best. Not going to do the test every 2 months. Maybe DS can chime in with the work around.
 

Tim Fitz

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Dec 25, 2019
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So today I went and flew and there was no battery test needed. So the Gremlin has retreated into the inner parts of my Dynon system, lurking to reappear at a time and place of his choosing.
 

Dynon

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When you do a successful battery test, SkyView stores the date/time of that test. Then on power-up, it checks that against current, which is kept alive if you have a SkyView backup battery attached. If you don't, then it'll acquire it when you get your next GPS fix. So it could simply be that - that the current date was unknown, and so it threw the error (and why it self-recovered another flight, presumably when there was a next valid date/time.
 

Tim Fitz

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Dec 25, 2019
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Think I may have figured this out. Only took a few months. About a week ago the same issue occurred again. Back up battery test required message even though it is less then a year since the last one. So yesterday I had the same issue still there and I took off on a 2 hour flight. In flight while drilling through some of the set up pages came across a “ back up battery voltage low on shutdown” message. Then after getting my chutes repacked fired up to fly home and message was gone. My theory is that the backup battery needed a good long flight to recharge. Not sure if that is printed somewhere or if it is institutional knowledge. Just throwing it out there as to why the issue may appear and then disappear on its own.
 

andresmith76

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Oct 4, 2018
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Think I may have figured this out. Only took a few months. About a week ago the same issue occurred again. Back up battery test required message even though it is less then a year since the last one. So yesterday I had the same issue still there and I took off on a 2 hour flight. In flight while drilling through some of the set up pages came across a “ back up battery voltage low on shutdown” message. Then after getting my chutes repacked fired up to fly home and message was gone. My theory is that the backup battery needed a good long flight to recharge. Not sure if that is printed somewhere or if it is institutional knowledge. Just throwing it out there as to why the issue may appear and then disappear on its own.
Or maybe the back up battery is on the edge of needing replacement?
 

Tim Fitz

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Dec 25, 2019
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Could be, but I am on my third one in 9 years. Not sure what the life expectancy is.
 

ned

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Feb 26, 2013
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Could be, but I am on my third one in 9 years. Not sure what the life expectancy is.
I am on the original 2014 battery and passed the annual test in July. I never use the bu battery for fiddling on the ground and have a lithium main battery so bus voltage is always high enough to keep the bu battery fully charged. Do not know if this helps extend bu battery life or not, but will continue the same practice in the future.
 

Janekom

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Dec 15, 2012
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Slight drift if I may please. On most aircraft I deal with the voltage on screen while in flight will be 14.2 to 14. V. I have a customer with an aircraft showing 13.8V max while flying. Not knowing the charging circuit can one assume that his backup will take much longer to fully charge. The manual suggests a charging time of up to four hours, but under what circumstances will it take four hours?
 

andresmith76

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Slight drift if I may please. On most aircraft I deal with the voltage on screen while in flight will be 14.2 to 14. V. I have a customer with an aircraft showing 13.8V max while flying. Not knowing the charging circuit can one assume that his backup will take much longer to fully charge. The manual suggests a charging time of up to four hours, but under what circumstances will it take four hours?
I would think when the battery comes close to nearly being totally discharged (around 10.5 - 11 volts?).
There isn't much of a difference between 13.8 & 14.2 volts and that difference wouldn't change the charge time by a large amount.
 
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Dynon

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Li-Ion battery/voltage curves are maddeningly complex to understand. But yes, if it were further discharged, it would take that period of hours.
 
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