Alternator issue?

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astaib
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Re: Alternator issue?

Post by astaib »

Hi,

Thank you for your feedbacks, it's more and more obvious that the VR is the reason, I'm still surprised because it has been already changed in 2017, 450 hours ago...

To bad that I cannot find one in spare somewhere to test before buying a new one...

I will let you know.

Arnaud.
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Rich
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Re: Alternator issue?

Post by Rich »

Talking about the battery (minor thread drift):

It's difficult to know what the operating temperature of the battery is. Diamond did go to the trouble of providing a cooling/venting air ducts to the battery case and alternator. It's hard to know how effective that is, but in flight it is forcing outside air to both.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Steve
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Re: Alternator issue?

Post by Steve »

Rich wrote: Sun Mar 07, 2021 2:54 pm Talking about the battery (minor thread drift):

It's difficult to know what the operating temperature of the battery is. Diamond did go to the trouble of providing a cooling/venting air ducts to the battery case and alternator. It's hard to know how effective that is, but in flight it is forcing outside air to both.
True. I have considered mounting a thermocouple to the battery, and running the wire through the vent window, but haven't done so yet. There is a 1 inch diameter SCAT duct which runs from the right air intake to the bottom of the battery box, but the amount of cooling flow would be minimal. Plus, in TX even the "cooling" air is > 86 degrees for half of the year... :)
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Re: Alternator issue?

Post by Rich »

Steve wrote: Sun Mar 07, 2021 3:20 pm
Rich wrote: Sun Mar 07, 2021 2:54 pm Talking about the battery (minor thread drift):

It's difficult to know what the operating temperature of the battery is. Diamond did go to the trouble of providing a cooling/venting air ducts to the battery case and alternator. It's hard to know how effective that is, but in flight it is forcing outside air to both.
True. I have considered mounting a thermocouple to the battery, and running the wire through the vent window, but haven't done so yet. There is a 1 inch diameter SCAT duct which runs from the right air intake to the bottom of the battery box, but the amount of cooling flow would be minimal. Plus, in TX even the "cooling" air is > 86 degrees for half of the year... :)
The size of the tubing is pretty small, but I'll wager it's coming in at significant volumetric flow, given the likely velocity induced by the pressure differential.

You don't need to come in through the vent window. There's actually enough of a gap between the canopy frame and the fuselage you could feed it through this gap. It dawned on me I have a device that would allow this kind of measurement. It doesn't record history but it'll capture max and display in real time. I think I'll try this sometime soon. I'm also curious about the ambient temperature in that rear portion of the engine compartment overall. If you open up the oil filler door after flight it subjectively seems pretty warm but I've not measured it and it's influenced by residual heat rising up from the exhaust system, oil cooler, and so forth.

I'm not particularly worried about longevity of the battery due to the in-operation conditions since the fraction of time the airplane is in operation vs parked (mostly in the hangar under temperature-controlled BatteryMinder management) is easily less than 1%.
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Rick
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Re: Alternator issue?

Post by Rick »

Steve wrote: Sun Mar 07, 2021 1:26 am... At 60-86°F, charging voltage should be 28-28.5 volts, so you are near the top of that range. The question is, how much of your charging time is spent with your battery at a temperature of 60 to 86°F? Remember this is not OAT, but battery temperature, inside the engine compartment.

Living in S. TX, I would wager that my battery spends most of its time charging at > 100°F. The high temperatures by themselves will shorten battery life, but high charging voltage will compound that issue. If 28.4 volts works for you, stick with it. I'm staying at 27.9 - 28.0...
Interesting information, Steve. It looks like I may want to consider setting my VR down to more like 28.0 too, at least during the warmer months. I have no idea what the battery temperature is during flight - I will be interested in the results of the tests you guys are discussing. I do keep a Battery Minder on mine all the time in the hangar.

Here is a link to the Concorde Battery document Stave referenced, in case anyone is interested in reading more.
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Steve
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Re: Alternator issue?

Post by Steve »

Something like this:

https://www.mcmaster.com/temperature-strips/

stuck on the battery would work well. I may pick up a few to stick on various critical areas inside the cowling. Of course, you would have to de-cowl right after flying to retrieve them. I might do it right before an oil change or my next Annual Inspection.
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Re: Alternator issue?

Post by astaib »

Hi,

Back to my VR or alternator issue.

I wrote to Diamond to ask them if they have any idea about my issue and if they have some recommendation to upgrade the VR by another one.

They sent me the enclosed document to check if it's an alternator/VR or wiring.

I attached it for you in case it might helps other.

I will make the trial tomorrow.

Arnaud.
Ground Fault Diagnostic Procedure.pdf
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Re: Alternator issue?

Post by Rick »

Thanks, Arnaud. I also meant to post this document earlier, but forgot. Here is more information about how digital Voltage Regulators work, along with some additional diagnostic information, in case you are interested.
VoltageRegulatorDiagnostics.pdf
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astaib
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Re: Alternator issue?

Post by astaib »

Hi,

I made the troubleshooting procedure and if I’m not wrong the result is that the voltage regulator is the guilty.

Before ordering it, I have contacted Lamar directly to be sure that I get I right.
And they told me that despite the result of the troubleshooting procedure it might also not be the voltage regulator :scream:.

The told me to check the connection of pin 6 and 8.
It is the ground and the voltage sensor.

Do you have any idea of where these wires are connected (I mean precisely)?
I want to check the connection and the sensor.

Thank you.

Arnaud.
Arnaud
DA40 Star 180 / 40.026 / 2001
Wingtip, landing and taxing LED (Whelen)
Skitube
GNS430 NON-WAAS
Steam gauges
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astaib
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Re: Alternator issue?

Post by astaib »

Hello,

I'm still with this bloody issue... My mechanics says that he has no idea about if it is alternator, voltage regulator or wiring.

Today, here is what I've done:
-Check connexion of the VR
-Check the connexion of the Alternator
-Check the ground connexion of the alternator
-Check on the lighter dashboard plug if the VM1000 voltage value are OK and how was them variating (with an analog volmeter)
-Open the VR to check visually if components are burned

A friend that is electronic engineer has studied the electric diagram of my DA40 and also my alternator, and he thinks that this is a diode issue in the alternator. The noise in the headsets is also pushing him in this direction.

I have made the test that Harzell is recommending at the very end of this video and the multimeter that I have, shows strange results.
The test consist of measuring alternative voltage on the lighter dashboard plug, if the reading is greater than 1v, then a Diode is leaking.
The value(s) that I read were blinking successively 3.45/OVERLOAD/18.55/--. Strange isn't it?
https://youtu.be/RocpYr5dmys

I'm really discouraged and I don't know what to do now...

My friend will come with an oscilloscope to plug it instead of the multimeter and do the same measurement describded above...
If it's a diode in the alternator, do you know if it is possible to repair?

Thank you.

Arnaud.
Arnaud
DA40 Star 180 / 40.026 / 2001
Wingtip, landing and taxing LED (Whelen)
Skitube
GNS430 NON-WAAS
Steam gauges
Non certified ADS-b
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