manu damaschin Posted February 8, 2014 Report Posted February 8, 2014 I have some charging problems: After starting the engine everything is ok until I engage some electric consumers (lights, pitot heat etc)...then the red light "low voltage" is flashing (not steady), even at higher RPM... The mechanic remove the alternator and said that everything seems to be ok, except the output from the alternator which is only 12-13 volts. The same value when measuring after the charging regulator. The output was measured before engaging the consumers...after engaging them, the value decrease and the red low voltage light is flashing. Do you guys have idea if is the alternator or the charging regulator? Thanks a lot!! manu
laytonl Posted February 8, 2014 Report Posted February 8, 2014 Manu, there are some past threads on this website that will probably help you with this problem. What is the voltage at the field "F" terminal on the alternator when the engine is off and the master switch is on? It should be slightly less than the voltage at the battery (maybe 1.5 volts max difference.) If this is okay, you may have a loose alternator belt or a bad diode in the alternator. An automotive shop can test the diodes in the alternator for you. Do you hear any whining noise in the headset? Lee
Guest Posted February 8, 2014 Report Posted February 8, 2014 Manu, Has your A&P checked the drive coupling for slippage? You don't have to remove it to do,a basic check. With the cowls off reach into the alternator with your finger hold the cooling fan now carefully turn the propeller with your other hand if you,can hold the fan with your finger the drive coupling has failed and will slip under increasing electrical load. If it does not slip you have to diagnose the regulator or alternator. Clarence
manu damaschin Posted February 9, 2014 Author Report Posted February 9, 2014 Thank you all for inputs...I will check and come back! manu
jlunseth Posted February 9, 2014 Report Posted February 9, 2014 Charging is a design issue with the 231 as you may know. The drive ratio of the coupler does not allow the alternator to provide charging at low idle. If this is a new (to you) 231, you will learn you need to keep the idle above 1000 rpm, and really above 1100, whether the components are all good or not. You have to choose between taxiing a little fast, or riding the brake. Second, the clutch is made of rubber that gets stiff in cold weather, so at engine startup it is best to tolerate the discharging for awhile and idle the engine at about 1,000 until you see the alternator coming on line (amps/volts will increase). Give it a couple more minutes and then use a higher setting, about 1100, and it will charge. I agree with Clarence, the most likely point of failure is the clutch. They seem to fail particularly fast if you fly in cold weather and do not give the clutch time to warm up at low idle. When I first got my 231 I went through a clutch a year. Having learned to baby it and give it a chance to warm up in cold weather, they are lasting much longer.
CoachTom Posted February 19, 2014 Report Posted February 19, 2014 Same conditions with my 231... I do the same as John Lunseth, tolerate the condition, keep the RPM up to a tolerable level, put the consumers on as I take the active (landing light, NAV if at night, strobe is on from start). I try to stay off the brakes and prevent any glazing by light application or over heating by riding the brakes. After landing, mostly everything gets turned off except radio to monitor ground and Landing light if at night... TMcD 1980 M20K
jlunseth Posted February 19, 2014 Report Posted February 19, 2014 One thing I did that really helped was to install LED landing lights. Been a few years so I don't remember the details but they were a straight substitute for the inca descents. Really reduced the draw especially during night ground ops.
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