Hi all, I'm a part time mechanic with an A&P, full time pilot and flight instructor. We have a 2007 Flight Design CTSW with only 250TT and the Amp meter indicates a discharge all the time. It seems to increase with power (full power = discharge rate of -50 to as much as -70, idle power = -3 to -10). No other indications that the discharge is actually occuring. Suspect it is an indication problem... Suggestions?
Amp meter indicates discharge all the time
- Thread starter dutch747
- Start date
dabear
New Member
So I guess this is a NEW indication with nothing being changed in the electrical system. If something was changed, change it back.
If it was an indicator problem you would be running down the battery over a flight. What does the battery voltage show over the course of the flight?
First, put a multimeter on line from the alternator/generator to the battery. What is it showing?
At first guess, you have an alternator or voltage regulator problem. But you need to check some things.
If it was an indicator problem you would be running down the battery over a flight. What does the battery voltage show over the course of the flight?
First, put a multimeter on line from the alternator/generator to the battery. What is it showing?
At first guess, you have an alternator or voltage regulator problem. But you need to check some things.
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- Mar 23, 2005
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Fundamentally, the ammeter is connected to a shunt, which is measuring the current flowing across it. Depending on how it's connected in your airplane (I'm not sure how FD wires them in the CT, and if that's changed over time), it may be set up as an ammeter (charge in/out of the battery) or a load meter (current coming out of the alternator, period). I'm guessing it's the former, if you're used to seeing zero.
The amps shunt has two wires going to it. If one of them was broken, you could see something like this.
The amps shunt has two wires going to it. If one of them was broken, you could see something like this.
Hi Dutch,,
The CT forum can probably help you out on all your CT needs. www.ctflier.com
You can give me a call and I can help you out. I think I can tell you what the problem is and you should be able to fix it in about 15 min.
Roger Lee
Tucson, AZ
520-574-1080
CT Service Center and Rotax Authorized Repair Center
The CT forum can probably help you out on all your CT needs. www.ctflier.com
You can give me a call and I can help you out. I think I can tell you what the problem is and you should be able to fix it in about 15 min.
Roger Lee
Tucson, AZ
520-574-1080
CT Service Center and Rotax Authorized Repair Center
Hi guys, to provide follow up, I checked the wiring to the shunt. There are a total of 4 wires/connections going into the shunt. I checked for continuity going into the shunt and discovered that two of the four wires go to pins 24 and 25 going into the Dynon EMS ammeter. One of which had a bad crimp which I corrected. However, the EMS is still not reading amperage correctly in my opinion. It is always reading around 0 amps even with the engine turned off and no charge. My opinion is it should read a discharge in this condition, then around 0 while the engine is running and the alternator is providing a charge. So fixing the crimp going into the shunt had definitely touched the problem, but not completely fixed it. Opinions are welcome.
Roger,
Didn't mean to be negative and I'm sorry if you took it that way. What I really mean is looking at the post in the technical section, I didn't believe the CTflier board would be useful in this regards, I may have been wrong!
The CT Flier board overall is an excellent forum and I read and learn from it all the time.
Best regards
Doug
Didn't mean to be negative and I'm sorry if you took it that way. What I really mean is looking at the post in the technical section, I didn't believe the CTflier board would be useful in this regards, I may have been wrong!
The CT Flier board overall is an excellent forum and I read and learn from it all the time.
Best regards
Doug
- Joined
- Mar 23, 2005
- Messages
- 13,226
Dynon recommends that each of the wires going between the EMS and the shunt be fused. Possibly one or both of those fuses is blown, though that probably isn't the case if you have full continuity from the shunt to the EMS connector as you stated.
If the Ammeter never has displayed a discharge (negative current values), then it probably isn't wired into the power system in such a way as to be able to measure discharge.
On the shunt there are four connections, 2 of which go to the ammeter on the D-120 (One high and one low) and continuity checked to pins 24 and 25. Three of the wires going out of the shunt have in line fuses and all three fuses are good. It was the connector in red I found to be improperly crimped.
Doug
Enclosed is a pic:
Doug
Enclosed is a pic:
