912UL Voltage High

by William Campbell in General Tech Discussion 7 years ago

I have a 2007 912UL engine. Voltage seems to be running higher than usual. Have EIS to alarm at 14.3 volts and it has been hitting 14.4 volts on a regular basis lately setting off the red blinking light. Ambient temperatures are high here in Fresno, CA in excess of 100F

What is an acceptable max voltage and if 14.4 is too high how is it lowered?

William Campbell

Re: 912UL Voltage High

by David HEAL » 7 years ago

David HEAL

23 186 410

What regulator/rectifier are you using? Ducati? John Deere?

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Re: 912UL Voltage High

by Roger Lee » 7 years ago

Roger Lee

125 5.12k 4.53k

If you bump 14.4 occasionally it isn't a problem.. If it goes higher and stays higher then you need to take a look. Out of curiosity, What kind of condition is your main battery in and do you have the required capacitor installed and is it in working condition?

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: 912UL Voltage High

by William Campbell » 7 years ago

William Campbell

15 25 43

I just checked on when I bought the battery and it is over 3 years old. So we will replace that right away. Also my partner is going to check to see if the capacitor may be leaking. I will get back to you after we replace the battery and check the capacitor.

Thanks for your input - greatly appreciated.

Bill

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Re: 912UL Voltage High

by Bill Hertzel » 7 years ago

Bill Hertzel

13 1.95k 7.96k

Before you blindly replace the battery...

Disable the ignition.
Crank the starter for 30 seconds. (Actually time it!)
Wait 5 minutes for things to cool.
Crank it again for another 30 seconds.
If it is still cranking, the battery is good!

14.4 is nothing to get concerned about.
It could be the high temperatures.
Don't overlook the measurement side of the equation.
Your 14.2v regulator could be creeping up to 14.3 in the heat.
And the EIS could be over reporting the 14.3 as 14.4 because it is also affected by the heat.
Put a quality Voltmeter on the battery to confirm the actual voltage.

Wet Lead Acid batteries can handle 15v all day
AGM Batteries should be limited to 14.7v
Gel Batteries should be limited to 14.5v

Your Electronics can typically handle at least 18v minimum.
Nothing should be designed that can't take at least 16v.
Most avionics are dual voltage and are good for anything from 10 to 30v.
They can be installed in a 12v or 24v plane.

Test the battery before you spend money needlessly.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: William Campbell

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Re: 912UL Voltage High

by Roger Lee » 7 years ago

Roger Lee

125 5.12k 4.53k

I agree with Bill. I didn't mean to imply that you should change the battery or even that it as bad. Just was curious during your trouble shooting if you had checked on these things.
Sorry if I implied to swap the battery.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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912UL Voltage High

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