Odd internal battery charge status

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11-17-2011, 09:08 PM
dnelson

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Odd internal battery charge status

Hi AFS,

I experienced an odd charge status of the internal Li-Ion battery yesterday. After a 1.2 Hr flight, I shut down in front of the gas pumps to fill up. Everything was powered off for the 13 mins it took to refuel. When ready to startup, I press Btn-1 to boot the EFIS and view the startup checklist as the 4500 is wired to the e-bus. I was immediately presented with a 'low battery - unit will shutdown' style mesg. I then used the POH to go through the startup checklist and taxied to the hangar (~2-3 mins) with everything on. After shutdown, the EFIS remained on for a minute or so (until I held Btns 1 and 5 to power off).

I've looked at the EFIS data and it confirmed that the EFIS was receiving ~13.5 VDC the entire time. There's a small bat_volts dip, from 8.4 to 8.2 VDC, which I can't explain. I believe the small spikes on the 'volts' line to be related to me operating the flaps and the wig-wag landing lights.

Attachment 70

Any ideas/suggestions as to why after a 1.2 hr flight the EFIS had a "dead battery" but after a 2-3 minute taxi everything was Ok?

Thank you,
/\/elson
11-18-2011, 10:17 AM
Rob Hickman

It looks like when it turned on on battery power it thought the battery was too low and decided to shut down. If it happens again try turning on the master switch to see if it resets the battery reading.
11-25-2011, 08:30 AM
dnelson

Hi Rob,

Will try out the 'Master' to ON then OFF to see if that offers any clues.

On a similar note, I noticed the other day that after a 2.8 hr flight and gassing up, then booting the EFIS on internal battery and increasing DIM to 100, the battery charge indicator went to zero and the unit shutdown. A subsequent reboot of the EFIS and leaving DIM at 50 (the default, if I recall) the unit ran just fine for checklist/startup. Does the display brightness put that much of a load on the internal battery? Firmware is 8.06.08 on a 4500.

Thank you,
/\/elson
11-27-2011, 03:03 PM
Rob Hickman

We automatically dim the screen to 50% on internal battery to make it last longer, if the battery is low and you turn the screen up to 100% it will shut down faster.