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  #1  
Old 06-28-2017, 08:19 PM
texdog texdog is offline
 
Join Date: Jan 2013
Location: Fredericksburg, Tx.
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Unhappy Eis and GRT EFIS voltage

I'm reading 13.8 eis voltage. I have the EFIS alarm set at 12 volts. Today at 6500 ft. 72 degrees OAT. The EFIS voltage would vary between 11.8 and 12.3 and set the alarm off. Odessie680 battery, Plan Power alternator. Is this normal? Could it be the voltage regulator? The Odessie battery is 2 years and 300 hours old. Any ideas are appreciated.

Thanks,
Fred
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  #2  
Old 06-28-2017, 08:42 PM
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Kahuna Kahuna is offline
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This would point to the charging system.
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Old 06-28-2017, 08:53 PM
rv7charlie rv7charlie is online now
 
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13.8V is marginal for a flooded cell battery; too low for an AGM. You're lucky the battery is still working. If voltage is down to the 12V range with engine running, the charging system isn't working. Could be the regulator or the alternator itself.
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Old 06-28-2017, 09:24 PM
BobTurner BobTurner is offline
 
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Quote:
Originally Posted by rv7charlie View Post
13.8V is marginal for a flooded cell battery; too low for an AGM. You're lucky the battery is still working. If voltage is down to the 12V range with engine running, the charging system isn't working. Could be the regulator or the alternator itself.
+1
You should set your alarm at 13.5 volts or so, so you immediately get an alarm if the alternator goes off line.
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  #5  
Old 06-29-2017, 04:44 AM
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rzbill rzbill is offline
 
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Hold on. This may not a battery or charging system problem if what you reported was 13.8 EIS and 12 on the EFIS at the same time. I also assume it has been this way since the beginning. It would be either an electrical system architecture issue (diode locations or style selection, or backup battery loocation) or a poor connection issue.

Are you the original builder and do you have intimate knowledge of the wiring or detailed records of same?
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Last edited by rzbill : 06-29-2017 at 04:46 AM.
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  #6  
Old 06-29-2017, 06:22 AM
texdog texdog is offline
 
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Default Eis EFIS voltage

Thanks gentlemen, I'm not the original builder and the GRT's were added after the original build. It has worked perfect for the last four years. I thought I would start this morning with the battery voltage and follow Plane Powers trouble shooting guide. I will be the first to admit that I'm weak on electrical. I think it's charging, because I've flown it 8 hours since this started. It maybe a lose connection or corrosion. I appreciate ideas.
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  #7  
Old 06-29-2017, 03:50 PM
texdog texdog is offline
 
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Angry EIS VS EFIS VOLTAGE

I know more now. The alternator is charging and the battery is staying charged.
The big issue is differential voltage. EIS is 12.5 static, battery, the EFIS is 11.5 or 11.6. GRT technical support is on vacation, but I was told the voltage should be similar. Also the standby battery, which I can't find, is 12.3. I have reset all of the cannon plugs. I would appreciate and suggestions.
Thanks,
Fred
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  #8  
Old 06-29-2017, 06:37 PM
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rzbill rzbill is offline
 
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My recomendation would be to start tracing the efis power feed line from the efis going upstream and measure the voltage at each connection point (switch, fuse, diode, etc) and find the point that the voltage goes up to 12.5 like the EIS reports.
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  #9  
Old 07-06-2017, 03:16 PM
texdog texdog is offline
 
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Smile Kahuna was correct

Kahuna is the man, he said it was the charging system! I replaced the Plane Power alternator with a different alternator and everything is back to normal. No help from Plane Power on this, they don't really support the alternator anymore.
I'm good, thanks.
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  #10  
Old 07-06-2017, 05:41 PM
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rzbill rzbill is offline
 
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Congratulations on the fix.

I am very curious what the two systems are reporting for voltage now.
The reported split between the EIS (13.8) and EFIS (12) should not have anything to do with the charging system.
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Unpainted, polished....kinda'
My RV Construction Page
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