more peeps need to just SAY SOME THING for THE ALLOWGROWTHRYTHEMz~!~~~~~!!!!!! lol HAVE AN AWESOME DAY!!! :) LOVE JOY COMPASSION

Thanks! Which plane do you have?

Camper seal tape ! Works great 👍

I was thinking the same thing, low pressure sucking it open. That said, I think I have identified the issue - the rearmost pawl wasn't moving forward far enough, which required the canopy to be pushed backwards to get around it - which means the rearmost part of the canopy was overlapping the turtledeck, rather than coming down and slotting into it properly. I've adjusted that pawl position, so I'll test this once the plane is back up and flying.

Good idea, I will do this.

Except this alternator is brand new, and the old alternator ran perfectly fine for 20 years with no problems. It was when the old one started showing sagging voltage that I switched out the alternator, and the new one was doing the exact same thing. Typical load in cruise flight is around 15 amps, and it is a 60 amp alternator.

I like the way you are thinking. If the new belt does not stop this issue, I think your post here is onto something. Conductance changing as things heat up.

It's possible...but this alternator is brand new, and the old alternator ran perfectly fine for 20 years with no problems. The alternator actually has a TON of cooling air pushed through it in flight, so it is not going to get very hot.

It's a Lithium Iron Phosphate (LiFePO4) - and it's designed for aircraft. It has extensive battery management, monitoring and protection circuitry inside, so yes, I'm 100% fine with it in the cockpit. Actually there are two of them, there's also a small one in the nose that is the EFIS backup battery.

Inflatable seals are typically only on pressurized airplanes. The canopy does have a seal and it's fairly pliable and in good condition. I think I might have found the issue however...

@@CanardBoulevard ah maybe I should have looked up what your Cozy’s max altitude was first :)

@@TF24218,000 foot ceiling. An oxygen system is on the want list. :)

​@@CanardBoulevardI was thinking the same, regarding inflating seals being on pressurised aircraft. I first came across them fairly recently with that Airbus where a passenger opened the door at a few hundred feet on landing approach. That door has inflating seals & I guess doors generally do, on pressurised aircraft. It looks like a very simple way to get a good seal but only where there's differential pressure.

When I talked to the manufacturer of the contactor, they said 0.19v drop is within limits (barely - 0.2v is the max). As for the alternator contactor, there is a very good reason for it being there. Alternators with built-in regulators can have a failure mode where the regulator fails and it starts generating very high voltages. There is a crowbar circuit in the airplane that will short out the field, which will trip the alternator field breaker and shut down the field to the alternator. However, if the regulator in the alternator has failed in such a way that it continues to put out voltage even when the field current is gone (this happens), it won't fix the problem. Therefore, the field current ALSO actuates a contactor on the alternator feed. Now when the crowbar circuit trips the field breaker, it shuts down the field AND physically disconnects the alternator from the bus in the case of an overvoltage, to protect the $20,000 in avionics that would otherwise be fried by the overvoltage.

Hi, the contactor may have 0.2 v drop at 100 amps but not 11 amps. You may actually be measuring the voltage across a bad crimp and not the contact. The field wire in the alternator makes a magnetic field in the commutator inside the alternator. The slip rings or wire would have to short to the +12v to fully energize the field. Shorting to ground is possible but not +12. This doesn't happen. You've got an odd problem with the voltage dropping over time. I've had loose belts, makes the voltage always low. Usually starts low as the load is high recharging the battery and then gets better. I'm going to guess that you have a bad crimp on one of your wires coming from the alternator. Just trying to help. I worked as a failure analysis engineer in military equipment and have seen many odd things with electronics. Built a canard airplane and owned 3 project airplanes.

I would normally agree with you about the bad crimps...except the voltage drop issue started occurring BEFORE that contactor was actually installed. Previously it was just the alt wire going directly to the current shunt, and from there into the main bus. The alternator failure mode I am talking about is when the solid state regulator internal to the alternator fails in such a way (supplying current to the field winding) that it supplies field current regardless of output. There are MOSFETS in there that can fail closed or open, and if they fail closed, the regulator loses control over the field coil current, and even shutting down the field will not solve it. That's the failure mode that the contactor is designed to avoid. I will definitely check the crimps however. You never know.

Hi, Good data point that the low voltage occurred before the addition of the Alternator solenoid. You are correct about active parts in the internal regulator. So first, without 8-12 volts on the field the commutator inside can't develop the magnetic field and the alternator stops outputting current. I think we both agree on that. So the 14V comes from the airplane, goes thru the regulator and becomes 8-12 volts that drives the field winding. An active device could fail and the regulator puts out 14V and the alternator output voltage goes to max. That is a possible failure mode. Shutting off the Alternator field 14V takes care of that. But it's got to happen fast, that's the reason for a crowbar monitor on the field input. This thing trips at say 15V and stays tripped. Everybody is happy. So lets explore the internal regulator failing shorted to ground. The alternator quits. No output. There is no failure mode that allows the field to be energized when the power is removed from the field connection. Now that we know you have an internal regulator, as that thing gets hot it could be malfunctioning. I now place my bet that the internal regulator is malfunctioning when it gets hot. Some auto part stores have a setup to run an alternator loaded and check for this. Might be worthwhile trying that.

I do have an infrared camera, and that's a great idea, I'll bring it out with me the next time I'm at the hangar. I think you're overestimating the current draw on transmit: my GNS530 draws a total of 3.6 amps normally, and that goes up to 6 amps during transmit. So only 2.2 amps added load for transmit.

@@CanardBoulevard RE: testing in TX MODE or testing the SIMULATED RADIO USE in the WHOLE TROUBLESHOOTING FORMULA.... that is. it's just banging around in the back of my head ''WELL THATS ABOUT THE ONLY THING HE HADNT FACTORED IN......'' *ABOUT* that is, there are a few things I amsure there are other factors... BUT eh... that and ''CONNECTIONS IN GENERAL'' BUT the IR CAM viewing it IN ACTION should illuminate any sketchy connections/wires heating up causing resistance issues...

​@@CanardBoulevard the setup you've done with the PSU in place of the alternator is ideal for an IR camera. I've been on a similar volt drop hunt on a car. Obviously with a car, you're just going to run the engine/alternator but that is going to create a difficult environment for finding slightly warm items when there's so much heat coming from the engine. It looks like you've got everything covered already but it would be interesting to look with the IR camera while you've got the PSU linked up. It's not going to be the case for you but my car volt drop was an engine earth stud on the gearbox. The stud was a hex section with a male thread at each end. Top end had the lead to the chassis, the bottom end screwed into the aluminium gearbox. Dissimilar metal corrosion in the thread, had created a significant resistance in the alternator negative return to the battery.

@@alanm8932 I'm definitely going to do that test with the IR camera - I want to see!