How to do a battery backup test?

Animosity2k

Member
Joined
Jul 19, 2019
Messages
36
I had an alert pop up the other day that a battery backup test is needed. I couldn't find it in my book. Is this easy to do?
 

DBRV10

Member
Joined
Jun 15, 2008
Messages
544
Location
Brisbane, Qld. Australia
Yes......fly for a reasonable time, say an hour or so, then shut down the plane. When the SV comes up with the 30 seconds till shutdown message, you will note a TEST BAT appear on one of the RHS buttons, press this and it will enter a test mode. Set your alarm so you can come back in 44 minutes to witness a successful or fail.

Message on the screen tells you all about it.
 

Animosity2k

Member
Joined
Jul 19, 2019
Messages
36
Seems easy enough! However, even when I am in the hanger playing with my electronics I get nervous to leave them on without the plane running for over a half four. This 44minute wait will not kill my battery?
 

swatson999

Active Member
Joined
Oct 6, 2010
Messages
1,098
It will deplete it to some level...that's what it's designed to do, test that the backup battery will last at least 45 minutes or an hour or whatever it is. You'll need to go fly for an hour or two to get it fully charged again after the test.

I believe this is all in the manuals.
 

DBRV10

Member
Joined
Jun 15, 2008
Messages
544
Location
Brisbane, Qld. Australia
Seems easy enough! However, even when I am in the hanger playing with my electronics I get nervous to leave them on without the plane running for over a half four. This 44minute wait will not kill my battery?

You will not deplete your main ship battery......turn the MASTER OFF, so that your screen runs on the backup battery. That is the point of the test. To prove it will go past 45 minutes. Typically a healthy battery will go past an hour or so.
 

Raymo

I love aviation!
Joined
Apr 25, 2016
Messages
702
Location
Richmond Hill, GA
You can also attach an external, appropriate, charger to your battery while one screen is on to re-charge the backup battery. Then do the other.
 

DBRV10

Member
Joined
Jun 15, 2008
Messages
544
Location
Brisbane, Qld. Australia
You can also attach an external, appropriate, charger to your battery while one screen is on to re-charge the backup battery. Then do the other.
I would not advise people to attempt things that they know little about.

The dunk battery gets charged when the system voltage is above a certain threshold, which a battery at rest is below. This way the backup battery is not charging with just a 12v battery on the system. It requires the alternator to be charging the system before the SV will charge the backup battery.

I wish people would not look for problems that dont exist or solutions to problems that dont exist. This is a non event........
 

HFMan

New Member
Joined
Aug 28, 2019
Messages
9
I think RAYMO's point is that after the backup battery test, one could leave one dynon display on (i.e. master switch on but everything else powered down) AND have a 3-4 amp charger connected to the aircraft battery. This will provide enough voltage and current to recharge the display's backup battery. I have done this is the past, as I don't always want to take off with potentially dead backup dynon batteries. I'd rather they be charged just in case I have the bad luck to have an electrical failure on that first flight after doing a backup battery test.
 

DBRV10

Member
Joined
Jun 15, 2008
Messages
544
Location
Brisbane, Qld. Australia
I think RAYMO's point is that after the backup battery test, one could leave one dynon display on (i.e. master switch on but everything else powered down) AND have a 3-4 amp charger connected to the aircraft battery. This will provide enough voltage and current to recharge the display's backup battery. I have done this is the past, as I don't always want to take off with potentially dead backup dynon batteries. I'd rather they be charged just in case I have the bad luck to have an electrical failure on that first flight after doing a backup battery test.

YES............THAT is a valid assumption. For me it never is a consideration due to my power architecture, but even a VFR is not that much at risk. After a taxi out and a take off, you will make it back with the new charge state. ;-)

But the serious point is, when giving advice, that can be assumed to be taken several different ways by, in this case a few very experienced dealers and avionics techs, who phoned me today, with a different assumption, it can be dangerous.

This has the potential for someone to do something dangerous based on not really understanding the post.

Lets not have solutions to a problem that does not exist. Even in your scenario, that is a problem that does not exist, even as you described. An IFR aircraft should not have that limitation, either two main batteries or two alternators. (note; not legal requirement, just sensible) so you are not at risk. A VFR aircraft is never at risk anyway, but the taxi and takeoff/climb time would give you enough charge for a data rich return. No problem actually, regardless of the perceived problem.

YMMV.....of course.
 

Raymo

I love aviation!
Joined
Apr 25, 2016
Messages
702
Location
Richmond Hill, GA
HFMan is correct and is how I do my test every year. There is no danger in doing so and Dynon has stated the same in the past. Would you recommend taking off with a depleted backup battery into IMC conditions? Not me. I'm not sure what part of my post scared you into that response.

All chargers must put out more than 12 volts or they would never charge the battery above 11.9 volts. Yes, the charger must supply more AMPs than the system is using, and is why you'd only have one screen at a time turned on, which is necessary for its backup battery to be charged.
 

HFMan

New Member
Joined
Aug 28, 2019
Messages
9
I was racking my brain trying to figure out what was "dangerous" about this- jees. I can also guarantee DBVR10 that there is no way a mostly depleted backup battery will be charged back up after just a taxi and takeoff- it takes at least 1 hour, closer to 1.5 to reach full charge.
 

DBRV10

Member
Joined
Jun 15, 2008
Messages
544
Location
Brisbane, Qld. Australia
I was racking my brain trying to figure out what was "dangerous" about this- jees. I can also guarantee DBVR10 that there is no way a mostly depleted backup battery will be charged back up after just a taxi and takeoff- it takes at least 1 hour, closer to 1.5 to reach full charge.
Did I ever say that a low state battery would be fully charged after taxi and climb? NO.

What I said was should the unlikely event happen as you climb out, there would be enough power in the main battery, or even if you had to switch the master off, there would be enough to make a prompt return and land. But you clearly have bigger issues here.

Read what I said again.

And yes it takes an hour and a half or so to charge the battery.
You can also attach an external, appropriate, charger to your battery while one screen is on to re-charge the backup battery. Then do the other.
What has the potential to cause confusion is the underlined bit. Which battery are you connecting a charger to while you test the other screen? Someone could read that as to mean directly to the SV-BAT-320.....because in most planes you would need to pull a breaker or via a VPX isolate the second screen while you did that.

I have written things assuming others knew what I meant, and confused people. I am suggesting you not do it too. Be more specific.
 
Top