Skyview Backup Battery weak

E

Exbonanzabucko

I love flying!
Joined
Jun 30, 2014
Messages
28
I have a Skyview touch in my Van's RV12 SLSA. I returned the unit to Dynon for repair after it failed in flight. They did a good job of doing that and sending it back. But ever since re installing it I have gotten the Skyveiw warning about a weak battery. The airplane has been flown about two hours since the repair and the alternator is working to spec...about 13.5V and 1 amp in flight. But the backup battery still is not charged.

What to do?

Thanks,
EBB
 
G

Garrett

I love flying!
Joined
Jan 5, 2013
Messages
208
Location
Tampa Fl
A few months ago I had the same problem. So I put the main battery on a charger and left Skyview on overnight so Skyview could charge up its backup battery. Never got battery message again. ;)
 
TRCsmith

TRCsmith

Member
Joined
Oct 24, 2006
Messages
254
Location
Suisun City, CA
Same here. Just got SV back last week now it says battery can't be check because battery voltage is below 11.? So went flying for an hour an A/c voltage at 14.1. Landed taxied back shut down and battery voltage still at 11.? to low for battery check  :-/
 
H

hmanvel

Member
Joined
Jul 25, 2010
Messages
97
I've never been able to get my backup battery fully charged. I gave up and used the software hack that someone posted, to fool it into thinking it passed the test. Now it wants to do the test again, I'll have to go back and search for that post with instructions how to clear the caution.
 
Dynon

Dynon

Dynon Staff
Staff member
Joined
Jan 14, 2013
Messages
14,222
Location
Woodinville, WA
TRCsmith - It can take a few hours of power on alternator to fully charge the battery. If, after a few more hours of charging, it's not getting to the 12ish range, there might be something up with the battery's ability to charge. Also, while your engine is running, confirm that SkyView thinks that it's charging the battery as shows on the battery status page in the setup menu.
 
Dynon

Dynon

Dynon Staff
Staff member
Joined
Jan 14, 2013
Messages
14,222
Location
Woodinville, WA
Harry - you're looking for this, though we'd love to get you sorted so you have a battery that is actually charged. Give our support team an email or call when you get a chance.
 
N

n456ts

Do not write below this line
Joined
Jan 24, 2015
Messages
161
12.6 Volts is a fully charged lead acid battery. I wouldn't worry about a 13.5V set point. Perfectly typical.
 
mmarien

mmarien

Murray M.
Joined
Dec 26, 2009
Messages
1,206
Location
Saskatoon SK CAN
I should have said 13.5V seems a little low for a 14V system. Internet consensus is 13.8V to 14.2V.

Page 9-4 of the install manual states that it may take up to 4 hours to fully charge the backup battery. Good enough reason to go flying again.  :)
 
D

dbdurrett

New Member
Joined
Dec 7, 2010
Messages
17
At Dynon's suggestion some years ago, I have a 6 amp charger from Harbor Freight ($29.99). Hooked up to the main battery, Master and Skyview on , they draw 3.7 amps leaving 2.3 for the backup battery. The nice part is the main battery never gets fully charged and the charger never shuts off. Takes about half a day.
DonD
 
Carl_Froehlich

Carl_Froehlich

Active Member
Joined
Aug 22, 2007
Messages
286
Many battery chargers like those from Harbor Freight are not filtered or poorly filtered, and some hammer the battery with pulses as part of the charge cycle. For charging a battery this makes little difference. Using it to run expensive electronics however is risky.

Unless you are using a regulated 12vdc power supply recommend keeping all electronics turned off when charging aircraft batteries. This includes electronic ignitions.

Carl
 
D

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
Carl,
All Dynon equipment is designed to DO-160 specs for 28V aircraft. This means it can handle 40V indefinitely and 60V for short periods. Devices made for 12V aircraft need to tolerate 20V/30V.

The whole reason for this is that alternators themselves aren't all that great and sometimes load dump. The world has figured out that it's really unlikely to get voltages higher than that even with big inductive dumps into the system.

The internal resistance of a PC680 battery is 7mOhms. This means that it takes 3,800 amps to raise the battery from 13.4V where it starts charging to 40V where it could cause a problem. It's only 100,000 watts. A house with 200A electrical service can only deliver half of that.

A battery is actually an excellent stabilizing device. It really doesn't like to go up or down more than a few volts. So as long as the charger is hooked to the battery, then it's really unlikely to cause any issues. I do agree that you shouldn't use a charger without a battery, or if it's not hooked direct to the battery where other resistances and impedances can cause issues.

And of course, a modern car has just as much electronics today, most of which can't be switched off, and when you charge a battery in car it's all still hooked up. You don't hear of them damaging cars.

--Ian Jordan
Dynon Avionics
 
Carl_Froehlich

Carl_Froehlich

Active Member
Joined
Aug 22, 2007
Messages
286
Thanks Ian - your engineering logic is sound and I agree having the battery inline when using these cheap chargers goes a long way toward avoiding trouble.

Your PC-680 example is good but it does not account for leaving a battery on a junk charger for extended periods of time. As the charger excess current is transformed into heat and Hydrogen as it depletes the electrolyte, a PC-680 (or similar battery) terminal voltage will go well above 20 volts.

Also considering that other avionics may not be as well made as Dynon, and that some users may end up with the battery not inline by mistake, my recommendation stands. Keep the panel off if trying to charge the battery(s) unless using a regulated power supply.

Carl
 
D

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
The Harbor Freight charger that was mentioned is a constant current charger that shuts off anytime the DC voltage gets above 14.4v. A depleted electrolyte battery will just lead to it triggering an error as it ramps up when you start it. It will not just keep raising the voltage of the battery. Try and turn it on without a battery present and it also throws an error as it refuses to start unless there is 10V present. It also won't keep pumping current into the battery. Once the voltage hits 14.4, it turns off completely. It's not a float charger.

As far as I can tell, it's a pretty robust design, which is why we recommended it. It's also cheap and easy to find, which is nice.

If you have some recommendations for other chargers that you think are affordable, safer, easy for people to find, hook up, and use, please share them.
 
You must log in or register to reply here.
Top