Jump to content

Low voltage warning light


Recommended Posts

I had a low voltage warning light come on during warmup yesterday.

I understand now, that the engine makes it's own electrical power, so i don't have to worry about the engine dying like i a car, if it's the alternator.


But my Glass panels went on batter backup then off, they eventually came back on during warmup (i never did get off the ground).


What i was wondering was, will the radios continue to work or do they run off the battery and they would eventually drain the batter?



Link to comment
Share on other sites

Your radio will not function. I had this problem last year. My regulator/rectifier gave up on me and I got the alternator warning light on. Not really a problem as long as you take the load off the battery by reducing to only what is needed. My opinion is you can turn off all the 'glass' and keep what is most important. In controlled airspace that would be the radio. Well, i was having too much fun flying that i didnt head back to the airport immediately. 30 mins later the voltage is going way down and i know that the radio will give up on me just when i need it most. Now i wished i had returned to the airport earlier. True enough, as i was on base i heard the tower ask me to report final. Not enough power to transmit! Dang !! This is where being prepared will help you. I had the handheld ready and continued on to land without any problem.

Link to comment
Share on other sites

Before replacing the regulator/rectifier in would go thru the troubleshooting guide. You should also check the connector to make sure it is fully engaged and non of the connectors are pushed out.

If you search for voltage regulator/ rectifier there will be enough information and guides to let you know if you regulator is actually bad.

Link to comment
Share on other sites

So, how much was that new regulator/rectifier? Is that something you can test and replace yourself?

Ooops. Sorry for possible mislead - i was not implying your regulator/rectifier was the problem - It was my problem. I am no expert at this at all. By chance, i had access to a friends identical part and tried it on my CTSW. The problem went away. I double checked by reinstalling the 'bad' part and had same problem come back. That was the extent of my troubleshooting. The regulator/rectifiers are not cheap. $170?? i think
Link to comment
Share on other sites


This is a copy of the instructions provided by ROAN.



Internal Generator Checks

1. If you have low voltage (battery not charging)

a. Remove yellow wires and check resistance between them

(0.3-0.8 Ohms) If the resistance is infinity or no needle

movement you have a open circuit (a wire is broken)

b. Reinstall yellow wires, run engine at idle and check output

from yellow wires (Should be 18-20 AC volts)

c. Check output from B+ terminal of Regulator. Should be 14

DC volts

2. If the Generator is putting out AC volts but the Regulator is not

putting out more than battery voltage (12V) the Regulator is faulty.

3. If the Generator is not producing AC volts the stator or stator

wiring is faulty

4. Check grounds on Regulator and engine block before ordering

new parts!

5. Check wiring diagram if you fail more than one Regulator! Faulty

Regulators are not common but crossed wires are!


BE SURE TO CHECK ALL YOUR GROUNDS AND THE REGULATOR/RECTIFIER PLUG CONDITION. I believe FastEddie posted pictures of a plug that had some arcing.


If you do find that the unit is bad you can purchase one from Lockwood, California Power Systems or any other Rotax parts distributor.


In order to maintain positive connectivity I put a tie wrap around the regulator and the plug to help insure vibration didn't create a problem.


If you were experimental you may have wanted to try the regulator made by a German company that is undergoing testing by our resident electrical guru Chanik. Here is a link if you want to check it out. http://www.silent-hektik.com/UL_R_912.htm


Good Luck troubleshooting your problem and be sure to report back what you find.

Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...