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Low Voltage


Jerry

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OK, I'm new to flying (one year) and new to CTsw ownership (2 weeks). I love this plane and love how it handles. One thing I've noticed before I bought it was a low voltage issue. The plane had to be jumped before the test flight. I had the voltage regulator and the alternator checked out, alternator was good and voltage regulator was suspect so I had the owner put a new one on and all was good for the first four flights. Then this past sunday I had to jump the plane to start it. Voltage read about 9-10 volts on idle and taxi, 12 -13 volts in the air. Open to suggestions, I thought the new regulator took care of the problem but I guess not.

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Gja533

 

Welcome to the site and congratulations on your ctsw!

I live about 1 1/2-2 hour flight south near KHVC ,My wife and i have been flying our ctsw for about 4 years now

We have a short private strip on our farm..

i have another friend who is closer to you being in shelbyville ky who also flies a ctsw.

So you have help pretty close if you need it. Im not sure about your charging problem? Give Roger Lee a call im quite certain he will have the answer youre needing.

 

Good luck

mack brame

270-887-5696

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How old is the battery? A low voltage poor battery can be a cause of many symptoms. What is the voltage before starting? If the voltage is low and the battery weak, even after jumping things will not run properly Had this happen to me with my buddy's plane with a battery that was basically defunct and showing 11.5 v. Things kinda worked but before that I had a battery in there which was only 6.5 V and nothing worked properly (electronics) although the engine worked fine. Things worked without any problems when I put a new battery in the plane.

Something to consider.

Lesson I learned is that when you have a sh%$#y battery hooked up, the engine works fine, but none of the electronics work right and the dynon switches every second from functional to back up power due to the intricate charging mechanism of the circuit. It requires a constant voltage of around 12V from the main battery and I that one is weak the electronics do not work properly.

 

Any comments?

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The battery has a pretty direct spade lug connection to the regulator. Just one of the firewall grounding bolts is in the path to battery charging. If the connections were poor then it would just charge slowly. Most likely he has an undervoltage regulator that never manages to charge the battery more than 10-20%. If the voltage settles out to ~12.7V or so while flying then it is a full volt too low to even float charge the battery. Should be over 13.6V

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Before you start trying all kinds of remedies try the cheapest, easiest and most common cause.

Tighten the grounds. If this is the problem you'll never fix the issue until this gets done and you need to eleminate it as the cause before you branch out to other causes that may cost.

 

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Gia,

What type of panel do you have?

 

It will be worth your time to remove and clean the connectors with some scotch rite. Then re-assemble making sure they are tight. I found that by adding a second jam nut after torque was applied to the primary nut they have not loosened. I also applied boeshield t-9 after everything was tightened up. Be careful when applying t-9. Once it goes on, it is only going to come off with a solvent. I made a small mask so as not to get it on the surrounding area. It will be worth your time to spend the time and upgrade your electrical system to eliminate the electrical grounding issue's we all face. There are more than a few suggestions on the best way to achieve a proper grounding scheme located within this forum.

 

While you are being proactive, I would also suggest that you take note of your max rpm achievable at your typical cruising altitude and during your takeoff roll to see if your are able to achieve 5500rpm wide open at your typical cruise altitude. If not then you may want to have that adjusted before you start down the high temperature path.

 

With regards to your voltage problem I would do the following.

1. Check the voltage that is coming into the regulator. This voltage is carried out of the stator on the 2 yellow wire. The manual gives the voltage which should be present.

2. Check the output of the rectifier, at the rectifier and verify the voltage present at idle.

 

You will find our CT's to be very basic machines and troubleshooting most issues is fairly easy if done in a systematic fashion.

 

Welcome to the CT Fraternity.

 

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  • 4 weeks later...

I am also new to the club I just bought a 2007 ctsw last month, love it! I added zaon traffic and upgraded to a 796. My problem is below 2500 rpm with position , beacon and landing lite on and electronics I show a discharge of 10 volts and the alarm goes off which is very distraction during landing. Once I go to 2500 rpm everything is fine? Also on takeoff max rpm if I don't have the landing light on I get an overcharge alarm, not really a problem because I takeoff with the light on and leave it on during flight.

Is this normal? If so anyway to ack the alarm and then not have it go off again as soon as I silence it?

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Check other threads here... One about replacing the landing light with a LED that draws much less current... and threads about the groundng system. I'd suggest a good tightening of all the ground points.

Tim

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Hi Darrenr,

 

That low voltage with the landing light at idle rpms is normal and either don't let it bother you or land with 2500-2700 rpm. The low voltage for the few minutes won't bother anything. We have talked about landing with power and here is a good time to use it. It is a non event and you may even make better and softer landings. On take off you should not be in an over charge mode no matter what is on or off. What is the high alarm limit set for? You may just have the voltage alarm limit set too low.

You can give me a call and we can discuss this and find you a solution.

 

520-574-1080

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Great, the high voltage alarm is sounding when the amp gauge not the battery volts is around plus 10 so I know it is not set at 15 unless u mean the battery gauge. Not to ask too much but can u tell me where the ground bar is? Firewall engine compartment or behind electronics in pod? Do u have a pic? Low volt is sounding when minus 10

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I see we are talking about the ammeter and not the voltage meter. Just raise the alarm limit on the ammeter to 15 amps and you'll be okay. The ammeter does move around a lot and it isn't any issue with the engine. It is the way the instrument reads. Most see any where from -4 to +10. Dynon knows and they are very slowly working on it.

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For informational purposes only,

After about 130hrs, our aircraft exhibited the same problems with the low output light becoming illuminated during the same times as yours. 150+ hours later the rgulator failed. I'm not saying yours will, but I would buy one and have it nearby. Once we replaced it the low voltage light has never illuminated in any configuration. That includes having a full electrical load at night at idle.

 

We did go thu and change the suspect grounding scheme.

 

 

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In the engine compartment it is straight up above the battery and up over the top of the engine mount bar. It is just an allen head bolt that goes through the firewall. Then you must take off the panel inside the cockpit on the passenger side. Then look straight back and you'll see it and all the white wires attached. Put a wrench on the through bolt and tighten it tight if it is an LS. If it is an SW then loosen the top nut hold the wires secure and then put a 10mm wrench on the nut against the bulkhead. Tighten the nice and tight then re-tighten the top nut holding the wires down.

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  • 3 months later...

We have been getting frequent low voltage alarms on our CTsw and the Engine red alarm light on the panel simultaneously. Curious that it is not the Alternator alarm light for low voltage. Is the Engine alarm the norm for low voltages?

 

We have tightened some (need to tighten all) ground connectors, and have separated the regulator connector and cleaned those contacts, which improved the situation but did not stop all alarms. After reading the earlier thread, I am thinking that we need to install the voltage-raising diode. Has there been any action from Flight Design on approving the diode installation, or do individual owners need to get a LOA?

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It isn't the low voltage issue off the reg/rec that a diode alone would fix. You most likely have a poor ground (most common) and there are 5 to tighten or it is possible to have a bad reg/rec. Put a wrench on every ground including the one inside the instrument panel behind the passenger panel and back against the fire wall. If you are at a low idle and have lights and other equipment on the voltage will drop and the light will come on.

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