Running avionics with engine off

[DrTimcat]

I have a Mooney ovation with all new Garmin glass panel. I would like to play with the radios and PFD to learn buttonology, but worried about running down the batteries. Any idea on best way to connect to an outside power source? And what power source and plug should I use?

[Jerry 5TJ]

Your Ovation has 2 batteries.   If you don’t have any external power you can run the avionics off one for a good while — I’d suggest stopping before the battery decreases to 21 volts.   Then start the engine with the other battery next flight.   

Although not intended for the purpose, if you have a battery minder connected while running the avionics the voltage will be supported for a long time.  

[EricJ]

A minder can't really keep up with the current load of the avionics system, but it'll make the battery last a bit longer than otherwise.

If you want to do this fairly often, you can get an APU that will support the avionics load and not put stress on the battery.    I'm an EE and built my own, but the ones you can buy these days are very good and not much more expensive than doing a decent one yourself.    Like this:

https://www.aircraftspruce.com/pages/el/powersupply/portPowerCharger24ces.php

 

[alexz]

On the Bravo minder allowed me for about 1.5 hours of avioncs buttonology with a mid life battery.  Engine did start fine next day from this battery even though i disconnected minder at the end of the session. Av30c voltage monitor held steady at around 28v all the time. 

[Mooney Dog]

While other have said using a gpu, a lot of newer avionics have trainer apps that allow you to play with the tech on your ipad or computer as well. I know there's some for the 650/750 GPS units as well as the 175/375 units. 

[DrTimcat]

Thanks to all of you for the great information. The plane has a GTN 750 touch, 375 touch, G3X touch and G5. I'll look at aircraft spruce and online for trainer apps. You all are lifesavers. Thanks again!

[DrTimcat]

EricJ - Went to the link. Do I need a special adaptor to fit the port on the ovation? And if so, where do I find that? Thanks again!!

[ArtVandelay]

Thanks to all of you for the great information. The plane has a GTN 750 touch, 375 touch, G3X touch and G5. I'll look at aircraft spruce and online for trainer apps. You all are lifesavers. Thanks again!

GTN app is available for ipad. G5 is pretty simple so probably not worth it.

[V1VRV2]

I did just that tonight. I got my Ovation back from the avionics shop. I ran the new panel on battery power for about an hour with no issues. Powered up the entire panel and even ran my TKS anti ice system for about 15 minutes on high. Going to start on the other battery next flight.

[Danb]

10 hours ago, DrTimcat said:

EricJ - Went to the link. Do I need a special adaptor to fit the port on the ovation? And if so, where do I find that? Thanks again!!

DT I just used the three pronged adapter to utilize the avionics. Make sure the master is on if you try to charge it. Be used mine for hours when I got the plane haven’t gone see for years since..

[Mooney Dog]

10 hours ago, DrTimcat said:

Thanks to all of you for the great information. The plane has a GTN 750 touch, 375 touch, G3X touch and G5. I'll look at aircraft spruce and online for trainer apps. You all are lifesavers. Thanks again!

This is very similar to my setup. You'll probably do most of your flight planning/editing on the 750 but as someone else said, both of those have ipad trainer aps from garmin. They are called GTN Xi Trainer and GPS trainer respectively. The bluetooth in the 375 will also allow you to link foreflight/garmin pilot on your ipad to your panel and transfer flight plans super easily.

 

The G5 is pretty barebones and a quick read of the manual should help you there. The G3x might be a little bit more but i dont have experience with that yet. 

[Greg Ellis]

GPS Trainer Aviation App | Garmin

This is the trainer app for the GPS 175, GNC 355, GNX 375 if anyone is interested.  I have used it for my GNC 355 and it helps.

[DrTimcat]

Thanks!!

[jaylw314]

22 hours ago, DrTimcat said:

Thanks to all of you for the great information. The plane has a GTN 750 touch, 375 touch, G3X touch and G5. I'll look at aircraft spruce and online for trainer apps. You all are lifesavers. Thanks again!

https://www8.garmin.com/support/download_details.jsp?id=12373

They're free.  The 530W simulator, in particular, is ancient, but was very helpful learning

Edited September 9, 2021 by jaylw314

[GeeBee]

On 9/7/2021 at 10:40 PM, DrTimcat said:

EricJ - Went to the link. Do I need a special adaptor to fit the port on the ovation? And if so, where do I find that? Thanks again!!

If you use that unit, I have one myself and it works great, make sure you use the #1 battery as only it is connected to the ground power plug.

 

[Aerodon]

A while back I looked at the life expectancy of some marine AGM batteries, the takeaway is that battery life (in cycles) is dramatically affected by the percentage discharge.

30% = 1200 cycles

50% = 550 cycles

100% = 320 cycles.

I keep my battery charged on a maintainer, don't ever let it run down more than I have to, and I typically get 8-12 years from Concord AGM batteries.

Aerodon

 

 

[PT20J]

2 hours ago, Aerodon said:

A while back I looked at the life expectancy of some marine AGM batteries, the takeaway is that battery life (in cycles) is dramatically affected by the percentage discharge.

30% = 1200 cycles

50% = 550 cycles

100% = 320 cycles.

I keep my battery charged on a maintainer, don't ever let it run down more than I have to, and I typically get 8-12 years from Concord AGM batteries.

Aerodon

 

 

What’s you criteria for replacing: failed capacity test, or just won’t run the starter anymore?

 

[201Mooniac]

3 hours ago, PT20J said:

What’s you criteria for replacing: failed capacity test, or just won’t run the starter anymore?

 

I use a battery minder and I got 8 years on my last Concorde RG-35AXC battery and it still passed the capacity test.  I replaced it before a trip just because it seemed old for a battery.  I know, not a good reason but...

[carusoam]

Good to have GPU plug…. https://www.aircraftspruce.com/catalog/elpages/jumperplug.php
 

When you have excess, and your forever plane has needs… https://www.aircraftspruce.com/catalog/elpages/audioathgpu.php

Battery #1 is the one that is connected to all the keep alive circuits… and the GPU plug… and has a tendency to drain slowly over a month of time…

PP thoughts only, not a mechanic…

Best regards,

-a-

[PT20J]

On 9/7/2021 at 5:07 PM, alexz said:

On the Bravo minder allowed me for about 1.5 hours of avioncs buttonology with a mid life battery.  Engine did start fine next day from this battery even though i disconnected minder at the end of the session. Av30c voltage monitor held steady at around 28v all the time. 

I added up all the typical current draws for my new panel and it comes to just under 4A at 28V. My 28V BatteryMinder is rated at 4A. So, it would seem that you could power the avionics using the BatteryMinder with very little, if any, drain on the battery. 

Skip

[Greg-ABQ]

I am curious now about my GPU plug on my 201...  Can I plug a BatteryMinder directly into the GPU with the 3 plug adapter and get the same results as plugging it directly into the battery relay?  I cracked open the access panel and verified the GPU plug is connected directly to the relay and battery (Concorde).  Thanks in advance.

GPU plug.HEIC

[carusoam]

10 minutes ago, Greg-ABQ said:

I am curious now about my GPU plug on my 201...  Can I plug a BatteryMinder directly into the GPU with the 3 plug adapter and get the same results as plugging it directly into the battery relay?  I cracked open the access panel and verified the GPU plug is connected directly to the relay and battery (Concorde).  Thanks in advance.

GPU plug.HEIC 3.09 MB · 1 download

The challenge you will encounter is…

the relay is dead until it gets the right voltage…

The BatteryMinder is dead until it sees voltage…

Supplying that first sign to get everything running can be a hassle…

It may help to have another battery in the tail, or the hangar to get things started…

PP logic only…

Best regards,

-a-

 

[EricJ]

49 minutes ago, Greg-ABQ said:

I am curious now about my GPU plug on my 201...  Can I plug a BatteryMinder directly into the GPU with the 3 plug adapter and get the same results as plugging it directly into the battery relay?  I cracked open the access panel and verified the GPU plug is connected directly to the relay and battery (Concorde).  Thanks in advance.

GPU plug.HEIC 3.09 MB · 2 downloads

The main issue is getting the minder to close the relay and keep it closed.   I don't think very many people have been very successful doing that, and the instructions with most minders say to wire the minder directly to the battery.   Trying to keep the relay closed also presents a constant current load to the minder, and they're not putting out a ton of current, anyway.

[LANCECASPER]

4 hours ago, Greg-ABQ said:

I am curious now about my GPU plug on my 201...  Can I plug a BatteryMinder directly into the GPU with the 3 plug adapter and get the same results as plugging it directly into the battery relay?  I cracked open the access panel and verified the GPU plug is connected directly to the relay and battery (Concorde).  Thanks in advance.

GPU plug.HEIC 3.09 MB · 2 downloads

No, from personal experience it won’t close the relay.

[flyboy0681]

14 hours ago, LANCECASPER said:

No, from personal experience it won’t close the relay.

What about running the avionics while the BatteryMinder is plugged in and charging? Will it produce enough juice under the load to keep it charged?