Running avionics with engine off

[PT20J]

26 minutes ago, flyboy0681 said:

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?

BatteryMinder is rated at 4 amps. How much do your avionics draw?

[LANCECASPER]

43 minutes ago, flyboy0681 said:

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?

I used to try that until I read this in a book written about the Piper PA46:

BatteryMinders42 have found wide acceptability as a trickle-charger and de-sulphating system. There are models designed specifically for aviation use, and these products will extend the life of the battery. They utilize pulses and reverse polarity for de-sulphating, so it is advisable not to operate avionics while a desulphating BatteryMinder is connected.

[flyboy0681]

1 minute ago, LANCECASPER said:

I used to try that until I read this in a book written about the Piper PA46:

BatteryMinders42 have found wide acceptability as a trickle-charger and de-sulphating system. There are models designed specifically for aviation use, and these products will extend the life of the battery. They utilize pulses and reverse polarity for de-sulphating, so it is advisable not to operate avionics while a desulphating BatteryMinder is connected.

That answers that, but with a GTN 750 and GI 275, I'm willing to be it's drawing more than four amps anyway.

[N201MKTurbo]

If you have a volt meter in your plane and it gets down below 12V while you are working with your radios, shut it down for a while and let the battery minder catch up.

[EricJ]

1 hour ago, LANCECASPER said:

I used to try that until I read this in a book written about the Piper PA46:

BatteryMinders42 have found wide acceptability as a trickle-charger and de-sulphating system. There are models designed specifically for aviation use, and these products will extend the life of the battery. They utilize pulses and reverse polarity for de-sulphating, so it is advisable not to operate avionics while a desulphating BatteryMinder is connected.

I usually forget and wind up doing my database updates with it connected, but, yeah, definitely better to disconnect the minder first.

[PT20J]

7 hours ago, LANCECASPER said:

I used to try that until I read this in a book written about the Piper PA46:

BatteryMinders42 have found wide acceptability as a trickle-charger and de-sulphating system. There are models designed specifically for aviation use, and these products will extend the life of the battery. They utilize pulses and reverse polarity for de-sulphating, so it is advisable not to operate avionics while a desulphating BatteryMinder is connected.

I'm not so sure about this. If it were a risk, I would think that the BatteryMinder manual would warn about it and I don't see any mention of it. 

A quick search of patents explains how desulfators work. They all send pulses into the battery at 3.26 MHz which is the resonant frequency of sulfur crystals. When the crystals are subjected to this energy the crystal structure is changed and the molecules dissolve back into the solution and create an active electrolyte. See patent US6184650B1. The various patents differ primarily in the means to generate the pulses. The aircraft power bus is pretty noisy and the avionics has to be designed to tolerate it. So, some 3 MHz noise would likely be filtered out by the DC-DC converters. Also, the battery makes a pretty good low pass filter.

I've operated my avionics (a mix of some old B-K stuff and some newer vintage Garmin/Aspen units) with the BatteryMinder running and never had a problem or heard any noise in the radios. I'm not saying it's not possible that there is an issue, but I'm skeptical.

Skip

[carusoam]

I’m pretty sure my battery minder has a button specific to operating the desulphating aspect…

That made me forget that it might have desulphating as part of the usual battery charging mode…

 

I would need a much bigger warning sign to avoid using this charger while my avionics are alive…. 

 

If I had sulphate in my avionics…. Accidentally  Desulphating them could be hazardous… (late night humor)

PP thoughts only, not an avionics guru…

Best regards,

-a-

[PT20J]

I just got off the phone with VDC Electronics tech support and was told that the BatteryMinders are designed to be used with avionics powered and will not cause any harm.

Skip

[carusoam]

Outstanding effort Skip!

Thanks for sharing the details.

Best regards,

-a-

[flyboy0681]

17 hours ago, PT20J said:

I just got off the phone with VDC Electronics tech support and was told that the BatteryMinders are designed to be used with avionics powered and will not cause any harm.

Skip

Good to hear but it remains to be seen whether it would produce enough juice to allow me to run a GTN 750 and GI 275 at the same time, even with everything else powered off.

[LANCECASPER]

If you go to Aircraft Spruce and search "gpu" there are a lot of options in the $400 - $800 range.

[flyboy0681]

4 minutes ago, LANCECASPER said:

If you go to Aircraft Spruce and search "gpu" there are a lot of options in the $400 - $800 range.

Your point is well taken, but why spend that kind of money for something used so infrequently if the BatteryMinder could handle it?

[N201MKTurbo]

You know you could hook a power supply to your cigarette lighter plug. It seems like an easy way to add some power to your plane.

[LANCECASPER]

41 minutes ago, flyboy0681 said:

Your point is well taken, but why spend that kind of money for something used so infrequently if the BatteryMinder could handle it?

1 hour ago, flyboy0681 said:

Good to hear but it remains to be seen whether it would produce enough juice to allow me to run a GTN 750 and GI 275 at the same time, even with everything else powered off.

Since as you mentioned in the previous the concern is there that it doesn't "produce enough juice".

[PT20J]

I just fired up my new panel with G3X with EIS, G5, PMA450B, AV-20-S, GTN 650Xi, GNC 255A, GFC 500, GTX 345, and a Guardian CO detector all running and the G3X shows a current of 4A @28V.  The BatteryMinders are rated at 4A @ 28V and 8A @ 14V. 

Skip

[carusoam]

Seeing if @DrTimcat is cruising by…

Have a look at Skip’s data above… valuable points there.

Best regards,

-a-

[ZuluZulu]

Something not covered in my POH is the proper sequence of events for running the airplane's systems on auxiliary power.  Should I turn the master on, and then plug it in?  Or plug it in first, then turn the master on?  

Note: I have a MINDer that is always plugged in, but I also have an external power unit that plugs into the power port.  Obviously I would not have both plugged in at once but I'm curious about the proper use of the external (non-MINDer) power.

28V system, Concorde battery.  The unit I have is the same one @EricJ posted earlier: https://www.aircraftspruce.com/pages/el/powersupply/portPowerCharger24ces.php

[EricJ]

4 hours ago, ZuluZulu said:

Something not covered in my POH is the proper sequence of events for running the airplane's systems on auxiliary power.  Should I turn the master on, and then plug it in?  Or plug it in first, then turn the master on?  

Note: I have a MINDer that is always plugged in, but I also have an external power unit that plugs into the power port.  Obviously I would not have both plugged in at once but I'm curious about the proper use of the external (non-MINDer) power.

28V system, Concorde battery.  The unit I have is the same one @EricJ posted earlier: https://www.aircraftspruce.com/pages/el/powersupply/portPowerCharger24ces.php

It's best to plug in the GPU with the master off, then turn the master on.   There's a potential discontinuity or spike in the bus when the GPU is plugged in and the relay switches to connect it to the bus, and the main way to avoid this potentially bothering anything is to plug the GPU in first when everything is off, then turn the master on.

 

[PT20J]

OK, this is why it is good to test stuff rather than just going by the specs:

Today, I ran just the G3X, G5, and AV-20 drawing 2A with the batteryMinder connected for about 2 hours while checking configuration settings. The BatteryMinder couldn’t keep up and the bus voltage slowly decreased from an initial 27.5V to 25.5V.

So, you can run the avionics with the BatteryMinder and it will slow down the battery discharge, but it apparently won’t completely stop it.

Skip

[ZuluZulu]

25 minutes ago, PT20J said:

OK, this is why it is good to test stuff rather than just going by the specs:

Today, I ran just the G3X, G5, and AV-20 drawing 2A with the batteryMinder connected for about 2 hours while checking configuration settings. The BatteryMinder couldn’t keep up and the bus voltage slowly decreased from an initial 27.5V to 25.5V.

So, you can run the avionics with the BatteryMinder and it will slow down the battery discharge, but it apparently won’t completely stop it.

Skip

I am beyond eager to see photos of your new panel...

[A64Pilot]

13 hours ago, PT20J said:

OK, this is why it is good to test stuff rather than just going by the specs:

Today, I ran just the G3X, G5, and AV-20 drawing 2A with the batteryMinder connected for about 2 hours while checking configuration settings. The BatteryMinder couldn’t keep up and the bus voltage slowly decreased from an initial 27.5V to 25.5V.

So, you can run the avionics with the BatteryMinder and it will slow down the battery discharge, but it apparently won’t completely stop it.

Skip

Bingo, but after you shut everything down, the battery minder will happily charge the battery to 100% SOC. occasional discharges so long as the battery is quickly recharged won’t hurt the battery at all. It’s leaving a battery in a discharged mode that will lead to sulphation.

I won’t argue that desulphators don’t work, but would ask why chargers costing hundreds of $, specifically built to charge and float LARGE banks of batteries like in a cruising boat don’t have them if they did? Large deep cycle banks cost thousands of dollars and weigh hundreds of pounds. Good large chargers have programmable equalization cycles, and everything is programmable.

What does work and is supported by pretty much every battery manufacturer is often called an equalization charge, which is a controlled intentional overcharge, follow your battery manufacturer's recommendation, not someone on the internet .

‘Concorde Ithink calls is it a reforming charge? It’s in their manual.

 

[PT20J]

I have been running the avionics on the BatteryMinder more while testing and adjusting things. With the full avionics suite drawing 4 amps, the BatteryMinder lets the voltage drop to about 25.2V and then kicks in and the bus voltage goes up to around 26.3V. So it turns out that I can run the avionics off the batteryMinder.

This makes sense after I thought about it since the BatteryMinder is really designed as a charger rather than a ground power unit.

Skip