Thread: low voltage warning with landing light

I always manage to get my EFIS screeching at me for low voltage (~11V) during night landings if the RPMs are at idle after a minute or so. Anyone else have this problem? It goes away as soon as I kill the light so maybe I just have a crappy battery, but it runs the starter just fien. What is the make and current draw of the landing light anyway? I can't seem to find a part number anywhere.

Thanks

Chanik, I recall that there's some threads that deal with this on the forum. I believe that it is not unusual to get a low voltage warning when you taxi with the landing light on. My knowledge of the charging system on our Rotax engines is limited but I think that the charging coil is a low amperage design which keeps up with the CT's current draw for all purposes EXCEPT for landing light usage. My steam gage voltage reading goes below 12v when I taxi with low engine rpm's with my light on. If you limit the use of your light, the voltage drop should be temporary and if you have a good battery you shouldn't be bothered by this temporary condition. Some owners are considering purchasing a LED landing light which I think FD now offers? Not sure that the cost justifies buying this. It seems to be very expensive and may not provide the same intensity of light that our current light provides.

Dick

Hi Chanik,

You have a bad ground just like a few others here recently. You need to tighten all the grounds in the engine compartment on the battery side. (the frame ground, under the starter soleniod, , the regulator/rectifier, the battery terminal) If it comes from the battery negative terminal then put a wrench on it whether it looks loose or not. Then tighten the grounding bolt that goes through the firewall just above the battery area. To tighten it you do it on the inside behind the right panel. it is double nutted. Loosen the top nut then tighten the bottom nut then re-tighten the top one. Your problem should disappear.


Hi Gys,

If you have any instrument or panel issues with fluctuations then 95% of the time it is a bad ground. The ground may look good, but it is only a partial ground. First thing is to tighten all the grounds and this usually takes care of the problem.

IMO, the alternator/generator doesn't create enough voltage at idle to run the 100W lamp. On my CT, with everything on, I need around 3000 RPM to keep the voltage constant.

I posted about this 2 years ago. I use a 50W lamp and my unscientific tests didn't notice much of a brightness difference when at idle during final approach.

It would be nice if there was a HID option that only drew 2-3 Amps.

Roger, thanks for the reminder to check ground connections. I did this a short while ago but will re-check these when the 100 hour comes up soon. Opticsguy, I sent you a message. Please take a look if you can. Thanks.

Dick

I have the same issue with a 2006 CTSW. Analog engine instruments, but D100 EFIS.
I've considered changing to HID light instead of the 100w MR16. See
http://www.duckworksav.com/Upgrades....Upgrade%20Kits
Both 35W and 50W ballast are available, could go on firewall beneath regulator.
Don't know if I can get an LOA from FD for that yet.
I will re-check my grounds per Roger's suggestion however !

Originally Posted by CCCT

I have the same issue with a 2006 CTSW. Analog engine instruments, but D100 EFIS.
I've considered changing to HID light instead of the 100w MR16. See
http://www.duckworksav.com/Upgrades....Upgrade%20Kits
Both 35W and 50W ballast are available, could go on firewall beneath regulator.
Don't know if I can get an LOA from FD for that yet.
I will re-check my grounds per Roger's suggestion however !

Sorry if I started a repeat string. I'll tighten stuff and use some pro-gold from Caig labs on the nuts. Works great to reduce contact resistance, BTW. I do think the 35W HID would be a great option if we could get an LOA. Has anyone ever tried?

Just wanted to strongly second Roger's advice on checking grounds. I had regularly been encountering the same problem Chanik described of low voltage warnings with landing lights on. I got to the point that I ignored them and got complacent -- and then ran into a total electrical failure shortly after take-off. No radio, transponder or flaps. I contacted Roger who suggested tightening all grounds, and the problem has entirely disappeared. Thank you, Roger!

I have the same issue - battery drain and lower voltage with the landing light on for a relatively short time. I had assumed my battery life was on its final days. Added to the lower voltage, i would also have my alternator light come on during idle rpm. Thanks for the posts as I will be checking my grounds, which is most probably the case, as pointed out by Roger regarding another issue I had with my oil temp/pressure fluctuations.
Chris Darza
Cebu, Philippines

Roger and those who are factory trained, what is FD's and Rotax's position on using dielectric grease on ground (and other) electric connections? What does A&P training say about use of dielectric grease on electrics? It looks like keeping the connections tight is the solution but I'm curious about preventing corrosion at the connections too. Or, maybe the grease allows loosening of the connections and isn't recommended due to this? Don't mean to beat this issue to death but it is an interesting subject. Thanks.

Dick