Keeping the battery charged

[Glen Davis]

I have a 1984 M20J. I would like to practice and learn how the avionics work by sitting in the plane, in the hanger, with the masters switch on, twisting knobs and turning dials. I’m concerned about depleting the energy in the battery while I do this. Is there any way to provide 12 V to the aircraft to run the electronics while the engine is off?  There is an auxiliary power port on the outside of the airplane to connect it to an APU. But, my mechanic has told me that will not supply power to the radio stack. Any thoughts?

[ArtVandelay]

I have a plug for auxiliary power port, just connect a battery charger. Trick is you need to close the AP port relay as most chargers won’t activate if it doesn’t sense a battery. I use one of the battery starters you can get at Walmart, so I connect starter battery, you’ll hear the relay close, then connect the charger.
I think that’s what the mechanic was trying to explain.
Other option is to remove battery door and connect battery charger directly.

[carusoam]

Glen,

There are a few threads around here covering the same question...

Some have purchased a really good power supply...

Some have built their own...

Others get by with a decent battery charger...  BatteryMinder...

 

You can use the ground power plug... be prepared to supply voltage to it to close the relay...

Smart battery chargers may not sense the battery to be charged, so they won’t send voltage to do any charging... a bit of a catch 22 situation...

Got a spare battery lying around?  Connect it to the ground power plug, and the battery charger to it...

With that much capacity, you’ll probably get bored of the instrument training faster than you run out of electrons... 

+1 for directly connecting to the battery...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Tom 4536]

I use the 12V ground power supply from Aircraft Spruce:  https://www.aircraftspruce.com/catalog/elpages/portPowerCharger.php 

I love it. Just plug the ground power into the plane, turn on the master switch and turn on the ground supply power. Viola...power to the panel to play with new avionics.

I use mine a lot.

[EricJ]

16 hours ago, Tom 4536 said:

I use the 12V ground power supply from Aircraft Spruce:  https://www.aircraftspruce.com/catalog/elpages/portPowerCharger.php 

I love it. Just plug the ground power into the plane, turn on the master switch and turn on the ground supply power. Viola...power to the panel to play with new avionics.

I use mine a lot.

That's a nice one!   That's not a ton more than I spent making my own, but I don't think these were available then or I'd likely just have bought one.  Mine has a cool display, but that's not that big of a deal.  I'm not sure I'd use one of those as a maintenance charger unless it was clear that it had the desulfating cycles, etc., that some manufacturers, like Concorde, recommend.

[RobertGary1]

Not sure what your mechanic means. Plug your plug in and plug the other in to your car battery and turn in your master and avionics switch.  I also have a ground power switch to run certain avionics with the master off ( set up flight plan, get clearance etc).  

[Mac80]

Have a similar question with 24 volt system. I need to do some software updates that may take some time. 

I have a 24 volt charger and plug in I routinely use to recharge battery.

I recall being advised not to use avionics while battery charging so I do not do that. However, it would be nice to leave on while updating software especially with my new task trying my transponder software updates.

Is there a definitive answer like never cycle avionics with battery charger plugged in? I do not know circuity between charging buss and plane but I think it goes directly to battery as I can charge the 24 volt Gill battery with master switch off

It is a 1994 MSE and I hear a connection being made when I insert the outside plug into the plane. I always have the systems off when I do this but would like to turn on master switch and avionics to power transponder when plugged in but done want to do harm. Once the avionics master is on many things are powered up.

Think charger I have puts out about 25 volts but I can check that first if needed?

 

[PT20J]

1 hour ago, Mac80 said:

Have a similar question with 24 volt system. I need to do some software updates that may take some time. 

I have a 24 volt charger and plug in I routinely use to recharge battery.

I recall being advised not to use avionics while battery charging so I do not do that. However, it would be nice to leave on while updating software especially with my new task trying my transponder software updates.

Is there a definitive answer like never cycle avionics with battery charger plugged in? I do not know circuity between charging buss and plane but I think it goes directly to battery as I can charge the 24 volt Gill battery with master switch off

It is a 1994 MSE and I hear a connection being made when I insert the outside plug into the plane. I always have the systems off when I do this but would like to turn on master switch and avionics to power transponder when plugged in but done want to do harm. Once the avionics master is on many things are powered up.

Think charger I have puts out about 25 volts but I can check that first if needed?

 

The reason for not powering equipment when charging the battery is that most of the current will go to the avionics rather than charging the battery. Also, many chargers don’t put out enough current to run a lot of avionics. Best bet is to buy a 28V ground power unit. 

[Mac80]

 

Good to know it should not harm.

I would like to use my current battery charger if that will help not draw down my battery.

It puts out about 10 AMPs when battery needs it and drops to less than one amp when fully charged.

I can turn off most of the avionics by buttons or pulling breakers.

If it does not hurt the avionics then why not leave it plugged in to side of the plane for software updates.

It is same port that the shop uses their ground charger on.

Presently, I just use battery, draw it down, and recharge later. 

I really need to try a new software update( MPC (MAT) operation with maintenance PC thru USB cable and laptop. I think the the breaker is only about 5 amps to the transponder. It is written on the breaker.

I don't wish to pay several hundred or thousands more for ground unit I rarely use. 

 

 

[Mac80]

My older 6/12/24 Schauer charger worked at only 5 amp charge for the connection to transponder and kept battery up.

Turned off most avionics and radios.

noticed Sportys sells a new Schauer power supply/charger for $399.