My voltage, in the hangar with the engine off is 12.6. And that’s with a trickle charger on all the time. With the engine started it’s 12.8, in the yellow range. Bad battery or?
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What is your battery voltage?
- Thread starter glenadavis
- Start date
If your measured voltage of 12.6 is with the charger disconnected, then that’s an indication that it’s not fully charged.
Based on the voltage you mentioned, I presume you have a P680. The fully charged static voltage of that battery should be 12.8 to 12.85 V.
The system voltage with the engine running should be high 13s to low 14s (depending on engine RPM and how depleted the battery got during engine start).
That is why 12.8 is in the yellow range, because it is outside of the normal charging voltage range.
There is a pretty high likelihood that you have some type of a charging system problem.
By the way, a trickle charger left on a P680, 24/7 is not great for the battery in my experience.
sansoneservices
Well Known Member
Engine running voltage should be 13.7-14.2 you should have the battery tested, replace if bad, test engine charging system with good battery
RV8Squaz
Well Known Member
You don’t say how you are reading the voltage. Is it on an engine monitor display or stand alone instrument? You need to verify that what you’re seeing is actually true and correct. I would check the open circuit voltage at the battery first.
I recently had a lower than normal and fluctuating voltage indication. I was convinced that it was my voltage regulator or perhaps increased resistance in the master solenoid. I have a Vision Microsystems VM1000C engine monitor display. It turned out to be a bad/dirty connection at the plug on the back of the unit. A little contact cleaner and re-seated the connector and my issue was resolved.
Grab your favorite voltmeter and work your way across the electrical system starting at the battery ground. My issue was presenting itself during flight only. Fortunately I have two cigarette lighter style power receptacles in my airplane, one of which is wired to the hot battery bus. I rigged a plug with two wires and hooked up my multimeter. It was easy to verify that the indicated voltage at the display was wrong.
Jerry
Piper J3
Well Known Member
Odyssey Absorbed Glass Mat (AGM) batteries require Odyssey battery charger which has special charging functions. Basically, the unit only charges when battery dips below preset voltage, otherwise unit is idle. Odyssey says charger is designed to be connected to battery full time. I have my battery always connected to the charger when the plane is in the hanger. Main advantage in having fully-charged battery is faster/stronger cranking to alleviate kickback that can damage Sprag clutch on starter motor.
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Today I measured the voltage on 3 batteries:
A brand new AGM intended for the tractor measured 12.5 volts. After measuring voltage, I put a charger on it.
The old flooded cell tractor battery measured 12.7 volts.
The old AGM used to start the Standby House Generator measured 12.8 volts.
A load test is better than measuring voltage. I put a 4 amp load on a fully charged battery and measured the time it takes for the voltage to drop to 11 volts. 4 hours is great, 3 hours is good and if 2 hours, think about buying a new battery.
Here is Bob Nuckolls' battery load test circuit:
http://www.aeroelectric.com/articles//Poor_Man's_Cap_Tester.pdf
And below is a battery test circuit that I made. Look at the very last post in this thread.
http://96.68.171.33/viewtopic.php?t...start=20&sid=c6e142c1e4e317e76396daab4ac5132c
A brand new AGM intended for the tractor measured 12.5 volts. After measuring voltage, I put a charger on it.
The old flooded cell tractor battery measured 12.7 volts.
The old AGM used to start the Standby House Generator measured 12.8 volts.
A load test is better than measuring voltage. I put a 4 amp load on a fully charged battery and measured the time it takes for the voltage to drop to 11 volts. 4 hours is great, 3 hours is good and if 2 hours, think about buying a new battery.
Here is Bob Nuckolls' battery load test circuit:
http://www.aeroelectric.com/articles//Poor_Man's_Cap_Tester.pdf
And below is a battery test circuit that I made. Look at the very last post in this thread.
http://96.68.171.33/viewtopic.php?t...start=20&sid=c6e142c1e4e317e76396daab4ac5132c
14.1 when the engines running
