G5 Battery issue

[Greg Ellis]

I have a panel with 2 G5’s.  One functions as the Attitude indicator and the other as an HSI.   I noticed after my flight yesterday that the Attitude indicator battery backup showed 73% while the HSI showed 100% charge.  I verified it again today.  When I turn on the master switch and the avionics master, the Attitude indicator indicates only 73% charge on the battery back up while the HSI indicates 100% charge.  I flew the day before but did not pay attention to whether it was draining after that flight or not.  I am just trying to troubleshoot before I call my avionics shop tomorrow.

Could it be the backup battery itself gone bad and not recharging when flying or is there some other issue?  No work has been done on the panel recently so I am not sure why all of a sudden this would happen.  Any thoughts?

and just for completeness, 1963 C model.

Thanks for any advice.

[PT20J]

Do you see the yellow lightning bolt symbol on top of the battery symbol indicating that the battery is charging when the master and avionics switches are on?

I'd double check the G5 by powering it up on it's battery with ship's power off by pressing the power button on the G5 to see if you get the same indication as when ship's power is on.

If you have a battery minder, I would turn off everything except the G5 and turn on the master and avionics switches and let it sit for a few hours and see if the battery charges. 

 

[Greg Ellis]

@PT20J I do not recall seeing the lightning bolt.  But I will check.  I will also try as you suggest to power it up without the masters on.   I do have a battery minder and will try as you suggest.  Thank you for the advice

[Greg Ellis]

So, I went and checked things out yesterday.  When the master switches are on, the Attitude Indicator shows a yellow lightning bolt supposedly charging.  When I power it up without the ships power, it does not show a lightning bolt.  I left the masters on for about an hour and the Attitude Indicator battery power did not move.  It stayed at 71% and did not charge at all.

The very weird thing is that if you sit there for a few moments with the master switches on and the backup battery charging, the battery indicator starts off at 71% then flips to 100% instantly and shows the lightning bolt still and then when you turn the master switches off, the battery indicator goes back to 71%.  Seems odd.

All this time, the battery backup indicator on the HSI stayed at 100%.

[PT20J]

3 hours ago, Greg Ellis said:

The very weird thing is that if you sit there for a few moments with the master switches on and the backup battery charging, the battery indicator starts off at 71% then flips to 100% instantly and shows the lightning bolt still and then when you turn the master switches off, the battery indicator goes back to 71%.  Seems odd.

This is normal behavior for mine. The battery status seems only to be accurate when the battery is not charging. When charging, it shows 100%. The only way to check the actual battery status is during a few seconds when first powered on ship's power, or to turn the G5 on without ship's power to cause it to run on the battery. I do the latter during preflight.

It sounds like the battery is not charging for some reason. Does the lightning bolt symbol have a black dot in the center? According to the Pilot's Guide, this means that the unit is running on ship's power but not charging the battery. 

One thing you could try is swapping the batteries between the two G5s to see if the problem follows the battery or stays with the attitude indicator.

[Greg Ellis]

There is no black dot in the center of the lightning bolt.  I will try swapping the batteries.  I also researched that there was an SB about this from Garmin in 2022.  I am not sure if my serial number falls in the ones listed but it stated that they had problems with the batteries not charging if left without power to them for multiple weeks.  Garmin apparently will pay for the removal, installation and repair of the unit (I guess a new battery).  SB22013. But it had to have been done by February, 2023 and this happened well after that.  Just noticed it within the last 2 weeks.

My airplane was down for quite while getting a new cylinder and a fuel pump.  I have about 10 hours on the airplane since this work and have now noticed this problem so I am wondering if mine falls under this SB.  But it had to have been fixed by February of last year to fall under the SB and mine was not so if I am having this issue I guess I will have to pay to have it fixed.

[EricJ]

There's a simple battery capacity self-test procedure in the manual for the G5, and it doesn't take very long to do.   If you're worried about the battery condition you might just run that and see what it says.

G5 Capacity Test, from 190-01112-11, G5 Part 23 AML STC Maintenance Manual and ICA.

4.2.8 Battery Capacity Check

1. Without power applied to the aircraft, turn on the G5 by pressing the power button in the lower

left corner of the unit.

2. Note the remaining battery capacity (%) at the top left corner of the display.

3. After about a minute, the remaining capacity will change from (%) to time (hour:min).

4. If the remaining capacity is less than one hour (1:00), allow the battery to charge until the

capacity shows greater than 95% and repeat the check.

5. If the remaining capacity is less than one hour (1:00) after charging, the battery must be replaced.

[Vance Harral]

4 hours ago, Greg Ellis said:

The very weird thing is that if you sit there for a few moments with the master switches on and the backup battery charging, the battery indicator starts off at 71% then flips to 100% instantly and shows the lightning bolt still and then when you turn the master switches off, the battery indicator goes back to 71%.  Seems odd.

I sympathize, this would seem weird to anyone who has an understandably simplistic idea of battery capacity.  But it's useful to understand there's really no direct way for a G5 or cellphone or any other battery-powered device to determine how much charge remains in the battery; so this idea of "percent charged" is something of a lie.  Modern battery-powered devices use computer algorithms based on empirical tests to estimate time/percent remaining, and those algorithms get less accurate as the battery ages.  Every such algorithm has weird corner cases that the designer desperately tries to avoid exposing to the end user, but sometimes they creep through.  Weird discontinuities are one aspect of that.  Another is the huge variability in how much longer a battery lasts once it's down to the "red zone" (10%, or whatever).

For some excruciating detail on this, you can start with https://batteryuniversity.com/article/bu-903-how-to-measure-state-of-charge.  Full on nerds like myself can go on to look at individual ICs that implement certain charge counting algorithms, e.g. https://www.analog.com/en/products/max17263.html

[Greg Ellis]

24 minutes ago, EricJ said:

There's a simple battery capacity self-test procedure in the manual for the G5, and it doesn't take very long to do.   If you're worried about the battery condition you might just run that and see what it says.

G5 Capacity Test, from 190-01112-11, G5 Part 23 AML STC Maintenance Manual and ICA.

4.2.8 Battery Capacity Check

1. Without power applied to the aircraft, turn on the G5 by pressing the power button in the lower

left corner of the unit.

2. Note the remaining battery capacity (%) at the top left corner of the display.

3. After about a minute, the remaining capacity will change from (%) to time (hour:min).

4. If the remaining capacity is less than one hour (1:00), allow the battery to charge until the

capacity shows greater than 95% and repeat the check.

5. If the remaining capacity is less than one hour (1:00) after charging, the battery must be replaced.

I read that as well and will try it.  However, should one expect the battery percentage to change after charging for one hour?  I had it on, on ships power, for one hour and the battery stayed at 71% power.

 

15 minutes ago, Vance Harral said:

I sympathize, this would seem weird to anyone who has an understandably simplistic idea of battery capacity.  But it's useful to understand there's really no direct way for a G5 or cellphone or any other battery-powered device to determine how much charge remains in the battery; so this idea of "percent charged" is something of a lie.  Modern battery-powered devices use computer algorithms based on empirical tests to estimate time/percent remaining, and those algorithms get less accurate as the battery ages.  Every such algorithm has weird corner cases that the designer desperately tries to avoid exposing to the end user, but sometimes they creep through.  Weird discontinuities are one aspect of that.  Another is the huge variability in how much longer a battery lasts once it's down to the "red zone" (10%, or whatever).

For some excruciating detail on this, you can start with https://batteryuniversity.com/article/bu-903-how-to-measure-state-of-charge.  Full on nerds like myself can go on to look at individual ICs that implement certain charge counting algorithms, e.g. https://www.analog.com/en/products/max17263.html

The world of electricity has always been a voodoo area for me.  Just never studied it in college or on my own at all.  I am thankful that my electrical devices take and hold a charge and work when I need them to, pissed off when they don't, but never clear on why it does or does not happen.  Electricity is a mysterious world to me.

[Ragsf15e]

53 minutes ago, Greg Ellis said:

I read that as well and will try it.  However, should one expect the battery percentage to change after charging for one hour?  I had it on, on ships power, for one hour and the battery stayed at 71% power.

 

The world of electricity has always been a voodoo area for me.  Just never studied it in college or on my own at all.  I am thankful that my electrical devices take and hold a charge and work when I need them to, pissed off when they don't, but never clear on why it does or does not happen.  Electricity is a mysterious world to me.

I would do the capacity check as @EricJ suggested.  I have even pulled the cb for the ADI airborne and just let it run on battery for an hour or more to see if the timeline was realistic.  If you let it run for a good long time on just battery, you can also see if it recharges at all since it will be lower than your current ~70%.

[PT20J]

Actually, I think this might be normal behavior for an aging battery. My G5 is 2-1/2 years old with about 250 flight hours. My SOP is to power up the G5 on it's battery during preflight to check the battery level. I look at the percent charged but don't often wait for the full capacity test to complete where it switches from percent to time. When new, it showed 98%. Lately it has been showing 93 - 95%. Today, I noticed that it showed 86%. I ran it on ship's power with the battery minder and it indicated charging (lightening bolt) and 100% during that time. After two hours, I shut off the master and powered up the G5 on battery for the capacity test. It still showed 86%. When it switched to time, it indicated 4:14. 

[vik]

You may want to recalibrate the battery indication in your unit. Let the battery discharge completely by running the unit on the battery until it dies and fully charge after that. The % of the battery remaining should realign with the battery state. You should get your 100% capacity indication back. The test will also show how long the battery will actually last in static condition, as I am not sure you can do the test in flight.

If I recall correctly, FAA certification requirement is 30 min. My guess is that Garmin puts 1 hour to be on a safe side and to account for more CPU/GPU load in flight, which will burn the battery faster.

Vik

 

[PT20J]

1 hour ago, vik said:

You may want to recalibrate the battery indication in your unit. Let the battery discharge completely by running the unit on the battery until it dies and fully charge after that. The % of the battery remaining should realign with the battery state. You should get your 100% capacity indication back. The test will also show how long the battery will actually last in static condition, as I am not sure you can do the test in flight.

If I recall correctly, FAA certification requirement is 30 min. My guess is that Garmin puts 1 hour to be on a safe side and to account for more CPU/GPU load in flight, which will burn the battery faster.

Vik

 

Interesting idea. The Aera 760 manual suggests running the battery down the first time it's used and then recharging to get full capacity. There is no mention of this that I can find in the G5 documentation and I don't know that it works with a aged battery, but it's worth a try.

From the Aera 760 manual:

INITIAL BATTERY CHARGING After fully charging the battery for the first time, the aera 760 battery indicator may report significantly less than full charge. In this case, the battery will need to be conditioned to report the correct capacity. This can be accomplished by allowing the battery to discharge completely and then fully recharging the battery.

[EricJ]

The G5 battery is a Li-ion battery, which don't generally respond well to deep-cycling.    The BMS may prevent a deep discharge that could damage the battery, or it might allow it since it is supposed to be an emergency backup.    In any case, I'd be hesitant to drain it (i.e., deep cycle it) very far without some specific guidance from the relevant manuals that that's not a Bad Idea.

FWIW, I have two G5s, one is about three years newer than the other, and my AI battery (which is the newer one), always reads way lower than the other.   My HSI battery usually indicates anywhere from mid-90s percent to 100%, and the AI is typicaly in the 80-90% range.    I capacity test them every year per the manual (since it's easy to do), and they're both still very healthy according to that.

[PT20J]

I sent the following to Garmin support:

My G5 (v8.20) is about 2-1/2 years old with approximately 250 flight hours. My battery has been showing a decreasing percent charge on the battery status indicator and currently only shows 86% even after several hours charging on ship's power. However, the capacity test concludes with 4:14 time remaining indicating a healthy battery. I understand that the Aera 760 requires calibration by running the battery completely down and then recharging. Is this necessary for the G5? Should I try this?

Support replied:

They are currently looking into G5 batteries not displaying correct state of charge. With your battery still indicating healthy I would not recommend trying that.

So, this sounds like a known problem being investigated by Engineering. 

[Greg Ellis]

13 hours ago, PT20J said:

I sent the following to Garmin support:

My G5 (v8.20) is about 2-1/2 years old with approximately 250 flight hours. My battery has been showing a decreasing percent charge on the battery status indicator and currently only shows 86% even after several hours charging on ship's power. However, the capacity test concludes with 4:14 time remaining indicating a healthy battery. I understand that the Aera 760 requires calibration by running the battery completely down and then recharging. Is this necessary for the G5? Should I try this?

Support replied:

They are currently looking into G5 batteries not displaying correct state of charge. With your battery still indicating healthy I would not recommend trying that.

So, this sounds like a known problem being investigated by Engineering. 

Thank you for this information.

 

[Greg Ellis]

Just an update.  My avionics guy came over and installed the latest software update.  Went flying on Sunday and battery showed 95% charged prior to the flight and 100% charged after the flight.  Just a reminder, it was showing 71% charged and would not show it was charging up even though there was a yellow lightning bolt indicating it was charging.

I then did the battery capacity check as suggested and the battery checks out good.  Yet another thing to keep an eye on….

[PT20J]

Interestingly, mine is now back to showing 95% and I didn’t change anything. I have SW v8.20. 

[PT20J]

Another thing to note when doing the capacity test is that the time remaining is highly sensitive to the backlight setting. So, if you want to compare readings from one test to another be sure to use the same backlight setting. 

[sortafied_sparky]

Avionics tech here,

Our fleet had some issues with a batch of G5 batteries not long ago. I found that the date range from 2020-2022 weren't so good. Most would not even take a charge and we're dead as a doornail. Garmin support was pretty helpful and RMA'd out about 10 batteries. It's worth a quick email to see if they will warranty out a battery.

Another note, when applying power to the aircraft, you can hold the power button and the depress on the selection knob and enter diagnostics mode. From there, find the diag tab and scroll until you find battery diag, this will show your battery health and charge state. Hope this helps!

[Fly Boomer]

6 hours ago, sortafied_sparky said:

Avionics tech here,

Our fleet had some issues with a batch of G5 batteries not long ago. I found that the date range from 2020-2022 weren't so good. Most would not even take a charge and we're dead as a doornail. Garmin support was pretty helpful and RMA'd out about 10 batteries. It's worth a quick email to see if they will warranty out a battery.

Another note, when applying power to the aircraft, you can hold the power button and the depress on the selection knob and enter diagnostics mode. From there, find the diag tab and scroll until you find battery diag, this will show your battery health and charge state. Hope this helps!

Thanks for sharing!  We have a lot of G5s around here.