Battery voltage

by in General Tech Discussion 8 years ago

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Re: Battery voltage

by Bill Hertzel » 8 years ago

Bill Hertzel

13 1.95k 7.96k

Battery circuits require extremely good connections.
Without trying to force Ohms law on you; just accept that a connection as small as 0.1 ohms would be catastrophic in a starter circuit.
0.001 ohms is more typical. And 100x more conductive. And neither of which you can even come close to measuring with consumer grade meters.

What Mike was trying to explain is that even very good, but slightly poor connections, can cause very small but significant voltage shifts.

That said, the regulator is spec'd at 14.2 +- 0.3 volts. Means that 13.9 to 15.5 volts could be completely normal in your aircraft.
The regulator is Not a high precision device. But it is good enough for its intended use.

All this voltage drop and tolerance "Magic" also applies to the measuring circuits.
You voltage measuring device also contains errors and drift.
If the regulator is on the high end of the tolerance band and the voltmeter is also, the two small errors can add to look like a nonexistent problem.
Place an accurate voltmeter on the battery. Does it match the panel reading?

The real question is, "What Voltage were you used to seeing on a daily basis?" <---<<< *** ???

If a normal 14.4 or 14.5 is occasionally crossing the line into the 14.6 area, don't panic YET! But keep watching it closely.

If you have just noticed that your normal 14.2 has just jumped up to 14.6, that is a different matter.
Something might be on the way out.

The first thing to check is to clean all the battery connectors that don't look like they need cleaning. (Yes!, I said that right!)
More than one person has blindly replaced his battery and declared that that solved the problem when the hidden issue was a bad connection that was resolved in the process of changing a perfectly good battery.

The urge to start changing things "Just Because Maybe" is called the "Shotgun" approach to troubleshooting.
The theory is that if you throw enough money at the problem, it will go away.
It is an expensive way to troubleshoot. But unfortunately, way more common than it should be.

Most common Multimeters priced below $500 can not accurately measure resistances below ~5 ohms.
At this low range, all you can really say is you have a reasonable connection or not. Nothing more.

However they can measure voltages well below 1 volt quite accurately.
This makes it possible to measure Mikes Voltage drops easily.

Set your test meter to DC Volts and touch the test leads together.
You should see 0.000 volts or somethig very close.

An example of measuring continuity accurately...

With the craft powered up, place one test lead on the Negative terminal of the battery.
Not the battery clamp, the actual battery Post of the battery.
Then place the other test lead on the frame or block next to where the other end of the battery cable attaches.
In theory these two points are directly connected and the measurement should be 0.000.
If it is not Zero, there is a problem.

Now, with the power ON, repeat this exercise by measuring both ends of any suspect connectors or wires in the circuit.
In theory both ends of any wires and both side of all connectors should not be electrically different.
You should be measuring a whole lot of Zeros. In this case, Zero is Not Nothing, it is a good connection.
If you find anything that displays a number other than Zero, further investigaton will be needed.

------------
As a closing comment, anything below ~13.8 will not charge a battery.
Your 13.6 means that the battery is discharging very slightly as you taxi in.
This is completely normal at idle RPMs and is to be expected and not of any concern.

Happy Hunting! :)

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

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Re: Battery voltage

by itemprop='name' » 8 years ago

0 0 0

Thx. very much for your explanation. I will follow your suggestions. Appreciate the help and guidance.
Terry

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Re: Battery voltage

by Garrett Wysocki » 8 years ago

Garrett Wysocki

1 572 1.45k

As stated in another post putting dialectric grease on the connection goes along way in maintaining a good connection/preventing corrosion.

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Re: Battery voltage

by Alan Arnold » 8 years ago

Alan Arnold

20 188 145

Try attaching a quality battery maintainer, like a Battery Tender Plus, to your battery between flights. My first PC680 Odessy lasted only 2 years while the second went 7 years thanks to this simple trick. The battery is always fully charged putting less strain on the charging system during and after the first start of the day.

Alan

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Re: Battery voltage

by Bill Hertzel » 8 years ago

Bill Hertzel

13 1.95k 7.96k

Thx. very much for your explanation. I will follow your suggestions. Appreciate the help and guidance.
Terry

You're Welcome!

This is Not a retorical question.

"What Voltage were you used to seeing on a daily basis?" <---<<< *** ???

We really do need the answer to be able to help you resolve your issue.

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

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