Voltmeter Gauge

[ducks136]

Today on the lake the gauge that shows the volts from the battery was not reading at all. After a little digging around on the internet I am not sure if it is a voltmeter or an ampmeter. The gauge only goes up to 16 volts. Any way how to do trouble shoot these things to determine if the gauge is bad or the alternator is going bad. Thanks

 

[NYBo]

Re: Voltmeter Gauge

If it reads in volts, it's a voltmeter.

What do you mean by "not reading at all"? Is the needle pinned to the left? If you were able to start your motor after the problem occurred, clearly something is up with the gauge or its wiring.

 

[ducks136]

Re: Voltmeter Gauge

The needle seems to be stuck at 0 volts all the way to the left side. When I switch the key from off to on the needle will sometimes barely move and then stay at zero.

 

[NYBo]

Re: Voltmeter Gauge

Start by checking the wiring. Attach a volt-ohm meter to the appropriate terminals on the back of your meter. if the VOM reads the proper battery voltage, your voltmeter is bad.

 

[ducks136]

Re: Voltmeter Gauge

I assume you have to do this with the motor running? Am I right?

 

[Art Bernard]

Re: Voltmeter Gauge

You can check the voltage on your batt and see if it's being charged or not. If batt has low volts that points you towards alternator problems, if it's good that points you toward wiring or gage problem. Check it when your running over 2k rpm as I don't think most alternators charge below that.

Art

 

[Silvertip]

Re: Voltmeter Gauge

No -- the engine does not need to be running but the key needs to be in the RUN position. You first measure battery voltage AT THE BATTERY TERMINALS. You then measure the voltage AT THE GAUGE. They should be the same. If the test meter reads the same as the battery voltage but the gauge is not registering, then the gauge is shot. If the gauge works but is drastically different than the test meter the gauge is bad. But chances are you simply have a loose connection.

The difference between a voltmeter and an ammeter is obvious: Voltmeters measure battery/charging system voltage. Your boat has a 12 volt system so a voltmeter (which is what you have) is calibrated from 0 - 18 volts. Ammeters also monitor the charging system but they monitor both current draw FROM the battery as well as current fed TO the battery by the charing system. Therefore, if the alternator is not keeping up with the current being drawn from the battery the system is considered to be discharging (even though the alternator is working -- it just can't keep up). If the current draw is less than the alternator output the system is charging. Therefore an ammeter will be calibrated from -60 -- 0 -- +60 (the right and left numbers may vary depending on the capability of the system). Minus (left of zero = discharge). Plus readings indicate charging.

 

[FunInDuhSun]

Re: Voltmeter Gauge

Make sure your + and ground wires have clean, tight connections. Check the wires for any cuts or breaks.
If all else fails to solve the problem, add this little meter to verify: http://www.harborfreight.com/12-volt-onboard-battery-and-alternator-load-tester-65928.html

 

[fishndirk]

Re: Voltmeter Gauge

I am a tank mechanic (8 years experience) and deal with complex electrical problems. Sounds to me like your sh*t just stopped working all of a sudden. If this is the case, alternators and voltage regulators (if you have one) dont just stop working all of a sudden. That kind of stuff is a loss of connection (wiring problem). Start from the component and work your way back (process of elimination). With a multimeter set on ohms if you have one.

 

[fishndirk]

Re: Voltmeter Gauge

Look, think of elctrical in 2 different systems, you have wiring harnesses, and you have components. Wiring harnesses only transfer signals from one component to the next, like a highway. Components actually do something with those signals. If you know that your wiring from one pin to the next (if you know the exact path of each wire, very important) is good ( 5 ohms or less), than it has to be a component. Some components have small internal wires which can fry. A key factor is knowing exactly what you did before the problem occured. If you were on board, sounds?, smells?, sights? How long between use? These are all factors.

 

[Sixmark]

Re: Voltmeter Gauge

Using a multimeter set to ohms in order to check voltage, that's a new one to me.....

 

[Silvertip]

Re: Voltmeter Gauge

Using a multimeter set to ohms in order to check voltage, that's a new one to me.....

Yup, putting an ohm meter on a powered circuit is a good way to toast it.

 

[fishndirk]

Re: Voltmeter Gauge

No, using a multimeter to test resistance in a cicuit with the power off! By eliminating wiring connections as the cause that basically narrows it down to only a couple of components. I never said anything about testing for ohms with the power on. I guess I was too quick to assume that everybody would have enough know how to disconnect from the battery before checking continuity. Just trying to get him to see how simple this stuff can be, its not like boat electrical systems are that complex...

 

[Sixmark]

Re: Voltmeter Gauge

No, using a multimeter to test resistance in a cicuit with the power off! By eliminating wiring connections as the cause that basically narrows it down to only a couple of components. I never said anything about testing for ohms with the power on. I guess I was too quick to assume that everybody would have enough know how to disconnect from the battery before checking continuity. Just trying to get him to see how simple this stuff can be, its not like boat electrical systems are that complex...

Actually tracking down an electrical issue on a boat can become very complex depending on the amount of items installed and what the problem is, and who is working on it.

There are many different people of different levels of experience on the forum, that is why we try never to assume anything as you may be giving advice to someone that can get them further into trouble.

 

[fishndirk]

Re: Voltmeter Gauge

True,...what I would say then just as an add on piece of advice is testing for voltage at the battery terminals for a charging issue such as this may not tell you anything. Ive seen bad batteries show about their proper voltage all the way up to the point where they die completely. A bad battery may still show just under 12 volts dc but may not have the CCA to get the job done. Testing to see if there is a difference in voltage while the engine is running makes sense though. But from what it sounds like, if your not having any trouble getting your engine to turn over, time and time again, then your battery is getting charged. So if your volt meter shows nothing in this case, then you iether have a bad gauge or there is some loss of connectivity between the gauge and the rest of the system (hence the continuity check). If your wire connections are all easy to get to though than this will be easy. Trust me, I do have A LOT of experience with troubleshooting electrical faults. An M1A1's electrical system makes the average boats look like a joke.

 

[Silvertip]

Re: Voltmeter Gauge

Look -- this little device is the simplest electrical device on the boat. To operate it only requires +12 volts with the key on and a ground. Next -- instrument wiring on a boat has +12 volts and ground daisy-chained from one gauge to the next. If the other gauges are working, the problem is in a six inch piece of wire feeding the gauge (either +12 side or ground side). There is no separate wire for the gauge running back to the engine. There is one wire from the "A" terminal on the ignition switch that feeds the striing of gauges. You verify the gauge by measuring STATIC battery voltage AT THE BATTERY. You then measure voltage at the gauge. If the two agree there is no voltage drop (regardless if the battery measures 8 volts, 10 volts, or 12.6 volts). If the test meter and the gauge read the same things are good but it would indicate the battery is not fully charged. (That still has nothing to do with whether or not the voltmeter is working.) This entire thread is not about the charging system working. It is about the gauge working. If there is +12 volts and ground on the gauge but the gauge doesn't show it, tighten the nuts or replace the gauge. Those are the only two points of failure. If you don't see voltage and ground at the gauge, then any gauge beyond the voltmeter would not be working either. Which gauges don't work will depend on where in the string the voltmeter is wired. If it's the first in line none of the others would work either.

Look at the generic wiring diagram in the stickies at the top of this page.

 

[Sixmark]

Re: Voltmeter Gauge

Look -- this little device is the simplest electrical device on the boat. To operate it only requires +12 volts with the key on and a ground. Next -- instrument wiring on a boat has +12 volts and ground daisy-chained from one gauge to the next. If the other gauges are working, the problem is in a six inch piece of wire feeding the gauge (either +12 side or ground side). There is no separate wire for the gauge running back to the engine. There is one wire from the "A" terminal on the ignition switch that feeds the striing of gauges. You verify the gauge by measuring STATIC battery voltage AT THE BATTERY. You then measure voltage at the gauge. If the two agree there is no voltage drop (regardless if the battery measures 8 volts, 10 volts, or 12.6 volts). If the test meter and the gauge read the same things are good but it would indicate the battery is not fully charged. (That still has nothing to do with whether or not the voltmeter is working.) This entire thread is not about the charging system working. It is about the gauge working. If there is +12 volts and ground on the gauge but the gauge doesn't show it, tighten the nuts or replace the gauge. Those are the only two points of failure. If you don't see voltage and ground at the gauge, then any gauge beyond the voltmeter would not be working either. Which gauges don't work will depend on where in the string the voltmeter is wired. If it's the first in line none of the others would work either.

Look at the generic wiring diagram in the stickies at the top of this page.

Exactly, for all intensive purposes it's a simple circuit consisting of a Voltmeter, Battery, and an on/off switch (ignition) in between them.