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  #1  
Old 12-13-2021, 09:25 AM
Flyingbeard Flyingbeard is offline
 
Join Date: Jun 2017
Location: Baltimore, Maryland
Posts: 51
Default Voltage Question?

Hi All of you Electrical Guys,

I have an RV-8 with a B&C BC460H 60 amp alternator controlled by a B&C LR3C-14 voltage regulator. All has been normal for the last 185 hours, but yesterday day I had a low voltage warning on start up. The voltage read 12 volts at first and slowly increased to above 12.6 volts and the warning went away. Almost like it needed to warm up. Is it possible the regulator needs adjustment due to winter operations.

Thanks in advance, for any ideas where to look and what to trouble shoot.


Mark
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  #2  
Old 12-13-2021, 09:53 AM
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Pat Hatch Pat Hatch is online now
 
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Default

First thing we need to know is where are we reading the voltage from.

If the voltage is reading from your main bus (most likely), then I would check your alternator for output. If the alternator is working properly, you would get a reading of around 14.3 volts or so depending on the adjustment on your regulator. A reading of 12.6 volts would indicate that only your battery is powering your main bus. Less likely, your regulator may be the culprit but I would look at the alternator first.

You didn't mention if you have an ammeter. If you do, what's it reading and is it connected to measure the amps out of the alternator or the battery?
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Last edited by Pat Hatch : 12-13-2021 at 09:59 AM.
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  #3  
Old 12-13-2021, 09:55 AM
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Carl Froehlich Carl Froehlich is online now
 
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Default

What is your battery no load terminal voltage? You can just use engine off buss voltage as an indication as well if getting to the battery terminals is too hard.

Carl
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  #4  
Old 12-13-2021, 11:13 AM
Flyingbeard Flyingbeard is offline
 
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Location: Baltimore, Maryland
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Unhappy Got called to work

Hi Carl and Pat,

First off, thanks for the quick reply! I just got called in to fly a trip for work and I will out of town for a few days. I will check the alternator out put and note the ammeter meter reading as soon as I can. I am also running two earthX ETX 680C batteries and will note there voltage also.
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  #5  
Old 12-13-2021, 11:41 AM
Avanza Avanza is offline
 
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Location: Vastervik Sweden
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Smile Alternator belt

BC alternator and regulator is very reliable.
First thing I would check the alternator belt for slipage.
Next thing, page 10, check the wire F on the back of the alternator.
It is subjected to vibration.

https://bandc.com/wp-content/uploads...evC.pdf#page=6

Good Luck
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  #6  
Old 12-13-2021, 07:07 PM
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RVbySDI RVbySDI is offline
 
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Quote:
Originally Posted by Avanza View Post
BC alternator and regulator is very reliable.
First thing I would check the alternator belt for slipage.
Next thing, page 10, check the wire F on the back of the alternator.
It is subjected to vibration.

https://bandc.com/wp-content/uploads...evC.pdf#page=6

Good Luck
Beat me to this. Before you get too deep into the troubleshooting try these first. Especially the loose belt. It can show on the volt meter as low voltage. Tightening the belt could be all that is needed.
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  #7  
Old 12-16-2021, 06:25 PM
Flyingbeard Flyingbeard is offline
 
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Default A little more information

I had the day off between trips this week, so quick trip to the hangar today.

Pulled the engine cowling off and inspected the alternator, the belt was tight and shows no signs of slipping. Voltage right from the alternator is 14.0 volts. Each of the EarthX ETX680C batteries voltage was 12.5 & 12.6 volts.

I ran the engine at 1090 RPM for a few minutes, system Volts read 12.2 and had a draw of 20 amps slowing decreasing to 12 to 11 amps.

No low voltage warnings today. it was unusually warm for December temp in the mid 50s.

For now, the plan is to watch and fly.
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  #8  
Old 12-16-2021, 06:37 PM
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Carl Froehlich Carl Froehlich is online now
 
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Quote:
Originally Posted by Flyingbeard View Post
SNIPÖ

I ran the engine at 1090 RPM for a few minutes, system Volts read 12.2 and had a draw of 20 amps slowing decreasing to 12 to 11 amps.

No low voltage warnings today. it was unusually warm for December temp in the mid 50s.

For now, the plan is to watch and fly.
No - absolutely not ready to fly.

Forget your low voltage warning - that can be set at any value. Your data that voltage never got above 12.2 volts says you have a problem. Normal bus voltage for you should be around 14vdc.

The current draw seems normal, so perhaps you just have a voltage instrument error.

You need to find out where you are measuring voltage. If you canít do that, do the same engine run with a multi meter connected to the main buss (the one that is fed from the battery that is on the operating alternator). This will tell truth, from that you can figure out what is going on.

One other data point missing, what is your battery terminal voltage, no load (as in the master(s) off)?

Carl
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  #9  
Old 12-18-2021, 08:19 AM
Flyingbeard Flyingbeard is offline
 
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Default Thanks Carl

Thanks Carl!

I am currently working this weekend and will be looking into next week.

I will post what I find.

Mark
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  #10  
Old 12-25-2021, 10:22 AM
Flyingbeard Flyingbeard is offline
 
Join Date: Jun 2017
Location: Baltimore, Maryland
Posts: 51
Lightbulb Update!

Merry Christmas Everyone!

While traveling for work, I called B&C Specialty and spoke with Nathan, he directed me to check the voltage the Alt, Batteries, and other places on the voltage regulator. The alternator and voltage regulator were operating normally.

Then I called Rob Hickman who built my Advanced Panel for help trouble shooting. We talked about my system and how it uses an ACM (advanced control module) Red Box and that I should check the voltage at the input power red terminal and the black ground.

When I got home, I checked the red power terminal and noticed some wires on it were a little loose. On closer inspection, I noticed evidence of sparking and heating from the loose wires. Removed the nut from the terminal and cleaned and inspected the wires. Replaced the Nylock nut and torqued the nut correctly.

On run up and test flight, system voltage is now a steady 14.1 volts. I am not sure, but the terminal nut must of been loose since installed and 180 hours of flight and turbulence must of combined to loosen up the eyelets to spark and create voltage fluctuations.

My thanks to Nathan and Rob! They helped me sort thought this issue.
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