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Author Topic:   High Voltmeter readings
PDM posted 06-14-2004 09:26 AM ET (US)   Profile for PDM  
I have an Evinrude 175 on a 96 Dauntless 20 and when I start the engine the volt meter gives me a high reading (maxes out). When the engine is off the volt meter reads in the 12-13 range.

Where is the volt meter supposed to be when the engine is off?

Does this sound like a volt meter problem or a voltage regulator problem?

rtk posted 06-14-2004 09:37 AM ET (US)     Profile for rtk  Send Email to rtk     
With the engine off the voltmeter will measure the actual voltage of the battery, typically around 12 volts unless the battery is discharged.

While running the typical voltage measured is around 14 volts.


PDM posted 06-14-2004 09:45 AM ET (US)     Profile for PDM    
Any thoughts on why I would be getting high voltmeter reading?

I've checked all the connections and they seem good.

My only suspicion is that in reconnecting the battery cables I connected something to the wrong post. I have two red cables (one thick and one slightly thinner) connected to the positive post and the thick black cable connected to the negative post. Additionally, I have a green cable and two smaller black cables attached to the negative post. Aside from the high voltage reading everything seems to run just fine.

Chuck Tribolet posted 06-14-2004 09:47 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
The problem could be either voltmeter or voltage regulator.
Get a second opinion: try another voltmeter. A good way to go
would be to spend $20 at Radio Shack on a Multimeter. You'll
find lots of other uses for it over time.


JohnJ80 posted 06-14-2004 02:55 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
Get the radio shack volt meter and check it out (good avdvice). The output voltage, when the battery is completely charged should be 13.8VDC. If it is higher than that, then there is a problem with the charging system but is probably a bad regulator (if this has been working fine in the past).


LHG posted 06-14-2004 03:01 PM ET (US)     Profile for LHG    
Volt meter is bad. It's less expensive to just go out and replace it. If this doesn't correct it, then you KNOW the engine needs service.
PDM posted 06-14-2004 04:35 PM ET (US)     Profile for PDM    
Thanks for all the helpful advice.
logjamslam posted 06-21-2004 01:49 AM ET (US)     Profile for logjamslam  Send Email to logjamslam     
I once had a battery fire due to a faulty voltage regulator. By the time I got the fire out I lost both oil tanks and batteries and felt lucky that I didn't lose the boat. A friend of mine had the same thing happen in a nonwhaler.

If the voltage regulator fails the battery can ignite after overheating. It is good that you are watching the guage and correcting the problem whether the problem is the guage or the voltage regulator.

jimh posted 06-21-2004 12:56 PM ET (US)     Profile for jimh  Send Email to jimh     
Many voltmeters are wired into the engine harness and do not indicate at all when the engine is turned off. It is impossible to say how your voltmeter is wired.

It is common that during engine operation and the engine alternator is putting current into the battery that the voltmeter will read 15-volts or more. Some outboard engines have regulators that limit the voltage output of their charging circuit. On a high-horsepower motor, like the 175-HP Evinrude, I would expect there to be a regulator that would limit the voltage output to about 15-volts maximum, otherwise the engine could produce some seriously high voltage output which could damage any electrical devices attached to the battery, as well as damage the battery itself.

The only way to determine if a voltmeter is accurate is to connect it to a source of known voltage(s) and compare the reading of the meter to the known voltage(s).

PDM posted 06-21-2004 03:06 PM ET (US)     Profile for PDM    
Thanks for your input. It looks like it is a faulty voltmeter but I will confirm my suspicions with a multimeter this weekend.

Plotman posted 06-21-2004 03:46 PM ET (US)     Profile for Plotman  Send Email to Plotman     
If you have a fixed mount Garmin GPS on the boat (perhaps other brands as well), one of the data fields you can display is battery voltage.


rtk posted 06-21-2004 04:40 PM ET (US)     Profile for rtk  Send Email to rtk     
Sorry, I should have stated that volt meter will read battery voltage when the engine is not running but the key is at the "run" or "on" position. With the key off the voltmeter will not read any voltage.


PDM posted 06-21-2004 07:48 PM ET (US)     Profile for PDM    

That's what I thought and that is why I think the voltmeter is bad. When the engine is off and the key is off the voltmeter still reads 12-13. It shouldn't read anything or zero.

Chuck Tribolet posted 06-21-2004 09:01 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Could be the key switch is stuck on. I'd get that multimeter
and just measure the voltage across the two obvious studs in
the back of the voltmeter. If the multimeter reads 12-13,
it's the switch stuck on, if it reads 0 it's the the boat's

Using your GPS or fishfinder to read the voltage probably
won't be helpful because it should be wired to the accessory
switch, not the ignition switch.

> The only way to determine if a voltmeter is accurate is to
> connect it to a source of know voltage(s) and compare the
> reading of the meter to the know voltage(s).

Wrong. That's not the ONLY way, though that's one way. Far
easier is to use any voltage source and another meter, and
compare the meter readings.

rtk posted 06-21-2004 11:19 PM ET (US)     Profile for rtk  Send Email to rtk     
The typical voltmeter on a boat will read 0 volt with key off. With the key in the on position without cranking the engine the meter should read actual battery voltage. When the motor is running the meter should read the voltage level of the charging system of the engine.

To check the charging system output to the battery take the multimeter, set it for 12 volts and place the probes of the meter on the battery positive and negative. While the engine is running take a reading. I think in general if you read anything under 16 volts and over 13 volts the charging system is in pretty good shape. An engine specification list should have the output voltage of the charging system for your motor. I think most charge a little over 14 volts. Readings in excess of 16 volts and under 13 volts general indicate a problem with the charging system or battery.

If you do not have a meter and have a test light you can check if the gauge is actually reading a 12 volt source. Connect the test light to a negative source, best is the battery. Touch the positive pole on the gauge. If it lights there is a 12 volt source to the gauge. If it does not light then there is no 12 volt source, gauge faulty, as others have said.

Hope this helps.


jimh posted 06-22-2004 12:18 PM ET (US)     Profile for jimh  Send Email to jimh     
Chuck--My statement describes your situation. Once you measure a voltage with another, accurate, meter, you now know the voltage. As I said, the only way to assess the accuracy of a voltmeter is to connect it to a known voltage. Now to calibrate the meter you are going to use to calibrate all the other meters, you may want to build a carefully controlled chemical battery, etc., but for the purpose of calibrating an analog meter on a boat, just about any 5-percent-accuracy multi-meter will do.

I think your suggestion to clip the multi-meter across the boat's voltmeter terminals was outstanding advise.

Chuck Tribolet posted 06-22-2004 09:41 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
You said "connect it to a source of know voltage(s)". That
implies you know the voltage BEFORE you connect it.


PDM posted 08-11-2004 11:17 AM ET (US)     Profile for PDM    
Thanks to all. As a follow-up to my questions in June I wanted to thank all who gave advise and comment. I replaced the voltage meter and everything works just ducky. I've been having a great summer with no other mechanical problems. Nothing like a mostly trouble free boating season to make you appreciate the value of a Whaler.

The voltage meter should read 0 when the motor is off and the key is in the off position. I guess I should have figured that out before playing electrician with the multimeter.

Alls well that end well.

Thanks again.

Chuck Tribolet posted 08-11-2004 11:58 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
A non-zero reading with the key off is PROBABLY a bad voltmeter,
but it could be a wiring problem where things aren't shutting

A multimeter is your friend. I keep a little radio shack
digital in the boat, a good Fluke 77 at home (overkill, but
I'm that way about tools), and a Fluke 77 in each of my two
labs at work. (Fluke, BTW, is the Boston Whaler of multimeters.)


backrivertom posted 08-16-2004 08:26 AM ET (US)     Profile for backrivertom  Send Email to backrivertom     
Same problem this month with a 1994 150 Johnson. Multimeter reads 12 volts ..gauge on console maxed out.

Fifty-tree dollars for a new Johnson meter and problem solved. A bit high but it matches the other gauges.


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