Voltage gage reads lower than battery

[pointblank1000]

2005 nitro 189 gages.
Installed a new voltage gage because the other one did not work, now I have 12.3 volts at the battery and maybe 10 volts at the gage. What could be dropping the voltage at the gage?

 

[Auger01]

Re: Voltage gage reads lower than battery

Is the guage indicating 10 volts or are you reading that from a multi-meter at the guage? One of the most common things that cause voltage drops are corodded connections and/or wire terminals.

 

[tazrig]

Re: Voltage gage reads lower than battery

+1 possibly also bad corodded sending wire but would think terminals first.

 

[bruceb58]

Re: Voltage gage reads lower than battery

You either have a voltage drop on the positive or negative wires between the battery and your dash.

1) Measure the posts of your voltage gauge with a multimeter to make sure it isn't just the gauge.
2) Using a long test lead measure the voltage between the positive post of the battery and the positive post of the gauge with ignition on. Should read close to 0.
3) Repeat step 2 but measure between negative of gauge and negative of battery. Should also read 0.

If you measure any significant voltage on test 2 or 3, that points to where your voltage drop is.

 

[pointblank1000]

Re: Voltage gage reads lower than battery

The gage is reading lower than the battery.
I'll try the 1, 2, 3 test this weekend to see if I see "zero" or ???
Bought this rig used and it shows signs of neglect and maybe sabotage. I have fixed most of the issues and proceeding with one problem at a time. Still saved a lot of cash buying it this way.
Don't recommend people buying vehicles this way unless you are willing to do a lot of work on it.....mainly labor.
So far it's paid off.

 

[bruceb58]

Re: Voltage gage reads lower than battery

So do you have an outboard or a sterndrive boat. It may matter when you come back for more help.

 

[pointblank1000]

Re: Voltage gage reads lower than battery

It's an outboard....when I measure the volts at the gage, do I need the key to be turned on?

 

[Silvertip]

Re: Voltage gage reads lower than battery

That would be a reasonable assumption! The voltmeter measures voltage. If the key isn't on there is no voltage to operate the gauge. If there was voltage at the gauge with the key OFF, the gauge would be reading it would it not? The same applies to all the other gauges. They require power to operate. Key OFF, no readings. Key ON, voltmeter, temperature and gas gauge work. Start the engine and the tach comes to life.

 

[pointblank1000]

Re: Voltage gage reads lower than battery

Ok, I took the boat out and ran the motor and the gage reads ok, 12.6. With the motor off and the key turned to on the gage reads 10.4.

 

[jhebert]

Re: Voltage gage reads lower than battery

Ok, I took the boat out and ran the motor and the gage reads ok, 12.6. With the motor off and the key turned to on the gage reads 10.4.

Generally there is little concern for voltage drop due to resistive loss with a voltmeter. The current drawn by the voltmeter is very small, and the typical current, only a milliAmpere or two, will not cause much voltage drop due to resistance. If other devices are also in the distribution path shared with the Voltmeter, those currents can cause some voltage drop.

Your readings suggest the engine charging circuit is working, and the boat battery is not very charged at the moment.

 

[bruceb58]

Re: Voltage gage reads lower than battery

You have a voltage drop between the battery and your helm. Do the tests I suggested earlier. You have a handheld meter right?

There is a load in the circuit where the voltage gauge is and that is causing the drop between the battery and the gauge.

Your 12.6V with the engine running vs 10.4V with it not only suggests that your voltage due to charging rises 2.2V which is probably normal.

 

[Scott Danforth]

Re: Voltage gage reads lower than battery

Just to clarify. the Volt meter at the back of your gauge is reading 10.4, or the gauge itself is reading 10.4?

 

[pointblank1000]

Re: Voltage gage reads lower than battery

Gage itself is reading 10.4v with the motor off and the key turned to on.
Have not run any test yet.

 

[Scott Danforth]

Re: Voltage gage reads lower than battery

so your $5 gauge is reading off. deal with it, so are the rest of ours. the gauges are mearly an indicator. if you want accurate gagues, be prepared to spend a lot of money.

you can pull your gauge appart and adjust the trim pot, however it may not get you close. you could also re-index your needle if you are consistantly 2 volts off.

 

[bruceb58]

Re: Voltage gage reads lower than battery

so your $5 gauge is reading off. deal with it, so are the rest of ours.

Unless there is resistance between the engine and the helm and you are reading low because there is a load. He needs to use a handheld meter and take some measurements.