Yesterday while flying my RV-12iS my Skyview (v16.7) issued a WARNING with the text BATT CONTACT LOW about 30 minutes into the flight. The error continued for about 10 minutes, then cleared on it's own. I've searched the Dynon manuals, Dynon forums, and VAF forums, and I can find no references to this error. It's not clear to me whether it refers to a problem with the main battery or the Dynon backup battery, or what it means by "contact low". I checked the battery voltages and both are fully charged. Does anybody know what this error means and what might have caused it?
Batt Contact Low Error?
- Thread starter jetset44
- Start date
Here's some more data to help understand this issue. I downloaded the Skyview data logs and plotted them on Savvy, and sure enough the sensor input for BATT CONTACT shows major voltage fluctuations at the 40 min mark, lasting about 2.5 minutes (it sure seemed longer than that in flight!). But the normal voltage for this sensor appears to be 5 V, so I don't know what battery this is referring to or see any references in the manual. Does anybody know? At this point in the flight I was doing some low speed maneuvering, so I wonder if that could have triggered this. This sensor went back to normal after I resumed normal cruise flight.
Thanks for the reply. Not that I'm aware of, but I can check. Everything on my plane is the stock Van's configuration.
Thanks again, Bob. What is a VP-X? And do you happen to know which voltage the BATT CONTACT sensor is measuring? It shows only 5V as normal, so it doesn't appear to be the main or EFIS backup batteries. Perhaps that's the input voltage for the Rotax EMS? Regardless, I'll start checking connections to try to find the issue.
Rhino
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- Jul 20, 2009
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5 volts is the internal bias voltage on the EMS pin. That should always be there. You might also want to look at the explanation here:
12V On/Off Inputs
My searches have helped educate me a little but I just wanted to confirm what I think I know by asking the question, without suggesting an answer.......this is my way of saying I have done some research :) I have two, separate, units that 'produce' 12V output when triggered. One is a low fuel...
airguy
Well-Known Member
Does the airplane have an EarthX battery in it? That battery has an internal fault indicator with an external wire that can go to the EMS to indicate a problem. That wire normally "floats" as an open wire, but when there is a battery fault the internal battery circuitry ties it to ground - also known as "low" in some electrical contexts. You could be seeing that battery fault indicator, assuming an EarthX is installed.
Thanks, airguy, very helpful! Yes, I have an EarthX battery and yes I have the fault indicator wire connected to the Skyview EMS-220. I'll add this to the list of things to check. The first thing to check is to make sure that fault wire blade connector is secure. Seems possible that engine cooling air or vibrations may have caused that connector to loosen.
airguy
Well-Known Member
That indicator is "grounded" to indicate a fault - so if you have a point where the insulation is rubbed through and it is shorting to ground, it will look like an intermittent fault on the panel.
airguy
Well-Known Member
If you don't find an obvious short to ground somewhere, the possibility exists that it is a legitimate alarm from the battery. Attached here is the fault-list for ETX
Very helpful again, airguy! In the time history plot in post #3, you can see the low voltage flashed every 5 seconds exactly for 2.5 minutes--which confirms this is likely a fault alarm coming from the battery. And since this occurred in flight and lasted only a short time, the EarthX fault table suggests the cause was likely that the cells were temporarily unbalanced during a period of high current charging. That makes sense since this occurred after about 15-20 minutes of low speed flight practice (stalls and slow speed maneuvering, flaps up and down), when the engine RPM (and thus generator current) was low but current drain was high. The flashing went away shortly after I throttled up. Nevertheless, I'll keep a close watch to ensure this doesn't indicate a more serious issue with the battery. I hope not, since both the battery and airplane are brand new (20 hours Hobbs time).
That said, I am a little surprised the Skyview reported this as a battery contact issue rather than a battery fault indication. In a non-EFIS system, the battery fault indicator would be wired to an LED on the panel and simply flash if there was a problem with the battery. The battery voltage to the bus wouldn't change, only the light would illuminate. But if I understand the Dynon data log right, it appears the actual battery voltage to the bus flashed here. Is that normal or typical? Am I reading that right?
Thank you for the help, this saved me a lot of time researching and troubleshooting!
That said, I am a little surprised the Skyview reported this as a battery contact issue rather than a battery fault indication. In a non-EFIS system, the battery fault indicator would be wired to an LED on the panel and simply flash if there was a problem with the battery. The battery voltage to the bus wouldn't change, only the light would illuminate. But if I understand the Dynon data log right, it appears the actual battery voltage to the bus flashed here. Is that normal or typical? Am I reading that right?
Thank you for the help, this saved me a lot of time researching and troubleshooting!
Rhino
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That isn't bus voltage. It's the indicator circuit from the battery BMS. The Skyview has no idea what's going on with your battery, because the BMS doesn't actually communicate with Skyview. What you're seeing is that same light going on and off. It's just doing that on the Skyview instead of on a dash light. It's intended only as a fault notification, not a diagnostic tool.