Backup Battery not holding charge?

[Flying_Monkey]

I have been receiving the error message "B/U BATT LOW CHARGE" after startup. Then I fly for 3 hours and check the battery status I the menu and it indicates it is receiving 13.75V and the battery is charging. I check back every 30 minutes and the battery status number increases until it finally reaches 12.16 and indicates "CHARGED." It appears to be charging. After shutdown I wait and then HDX and D10A go through the countdown and automatically shut off.

When I start back up I receive the same error message and the battery indicates a low number (in the 10 something range) on the STATUS page.

I am 100% sure the MASTER switch is off each time.

My install is about 5 years old.

Any ideas?
Thanks,
Eric

 

[Rhino]

You may need a new battery. Have you performed the battery test?

Has anything at all changed with the system that could have made this happen?

What software version are you running?

 

[Flying_Monkey]

The last time I performed the battery test at annual (Oct) it passed. Yesterday I flew and did not receive the error message.
So far here is the most recent sequence
L.A. to RENO - after startup, B/U BATT LOW CHARGE appears, fly 3 hours and battery indicates full charge at end of flight
RENO to LA 4 days later - after startup, B/U BATT LOW CHARGE appears, fly 3 hours and battery indicates full charge at end of flight
The next day - LOCAL FLIGHT - batt indicates fully charged after startup, no error message

Nothing has changed with the system. Running the latest certified software (I believe it is 16.4).

Each time I have watched the HDX and D10A countdown and auto shut off after master switch is turned off.

Seems strange to me.

 

[OgieOglethorpe]

Sounds like the battery has gone tango uniform. If it's ever been completely drained somehow it's pretty well toast. Wonder if there's a parasitic draw somewhere or even a loose connection

 

[Rhino]

I tend to agree this is likely a battery issue. You could ask Dynon directly before spending the money to replace it.

 

[chriscalandro]

The battery can go bad that fast. I’m just over at bracket and think I have a spare if you want to try it. 5 years for these is pretty good.

 

[N42AH]

If you have a gpu plugged into the aircraft on the ground will this power source charge the backup battery as opposed to being in flight to charge the battery? And obviously with all the avionics powered on.

 

[RV8JD]

If you have a gpu plugged into the aircraft on the ground will this power source charge the backup battery as opposed to being in flight to charge the battery? And obviously with all the avionics powered on.

Yes, with the following caveats:

 

[N42AH]

Thank you, I always enjoy associating with people that are much smarter than I am and have their finger on the answer.

 

[RV8JD]

You’re welcome. Amazing what one can find using CMD+F and copies of the System Installation Guide and Pilot's User Guide!

 

[Rhino]

It's Ctrl-F on my devices.

 

[KenLeonard]

I am having the same issue but my battery is less than 2 yrs old. Plane has 25 hours total, all in the last two months.
I have rotax 914 and dynon is showing 13.6 volts of charging while making power.

 

[Flying_Monkey]

update: I have been careful to watch the Dynon screen after I turn mags off and master off when shutting down. The last several times I have watched it countdown and turn itself off automatically. The battery seems to be fine and holds charge and is good the next flight- no error message and shows a good charge. I have a feeling somehow the unit has occasionally not been detecting that the ship power has been cut or maybe I have been touching the screen after shutdown (unlikely). I may elect to just manually press the SHUT OFF or TURN OFF whatever it's called button after shutdown to ensure the HDX is shutting down and not leave it to the automation/countdown. Will report back after a few more weeks of testing.

 

[airguy]

update: I have been careful to watch the Dynon screen after I turn mags off and master off when shutting down. The last several times I have watched it countdown and turn itself off automatically. The battery seems to be fine and holds charge and is good the next flight- no error message and shows a good charge. I have a feeling somehow the unit has occasionally not been detecting that the ship power has been cut or maybe I have been touching the screen after shutdown (unlikely). I may elect to just manually press the SHUT OFF or TURN OFF whatever it's called button after shutdown to ensure the HDX is shutting down and not leave it to the automation/countdown. Will report back after a few more weeks of testing.

The screen will remain alive on battery power if it thinks it's in flight - normally detected by airspeed. If you have a windy hangar location it's possible there is enough gusty wind conditions to make the unit think it's still in flight, or you might need to repeat your "zero-speed calibration" routine to make sure it knows where zero is.

 

[tcbc8222]

I am having issues with the BU battery showing as Failed in the test but is charged. Is there a way to make it go into test mode? My right screen BU battery tested and passed. Both batteries show charged. I use my plane for IFR and am supposed to have BU working correctly.

 

[airguy]

I am having issues with the BU battery showing as Failed in the test but is charged. Is there a way to make it go into test mode? My right screen BU battery tested and passed. Both batteries show charged. I use my plane for IFR and am supposed to have BU working correctly.

Power the screens up on ship power, then turn off your master switch. The screens will go to the backup battery for power and display the "shut down in 30 seconds" message. On the bottom there are some other options you can press a button for - one of them is "battery test".

 

[tcbc8222]

Power the screens up on ship power, then turn off your master switch. The screens will go to the backup battery for power and display the "shut down in 30 seconds" message. On the bottom there are some other options you can press a button for - one of them is "battery test".

The battery test button is grey and doesn’t allow use.