Voltmeter Connection wires

ed_dash · 02 March 2010, 16:17

Hi

Im going to connect a voltmeter and i wanted it so they come on when i turn the ignition on. Does anyone know what wires i would need to connect the gauge on from a Mariner / Mercury side mounted control box?

Thanks

Ed

Nos4r2 · 02 March 2010, 17:00

You could probably do it from the power feed to the revcounter.

jwalker · 02 March 2010, 23:01

The ignition switch controlled power feed, ie, anything which receives power when the ignition is switched on.

ed_dash · 02 March 2010, 23:33

ive got a rev counter so will have a look at the wires going to it.

JABS · 03 March 2010, 07:05

Can I ask why you want a Voltmeter?

doggypaddle · 03 March 2010, 08:32

Quote:

Originally Posted by JABS

Can I ask why you want a Voltmeter?

....So he knows the battery is charging in the absence of any other indicator.
I use the volt meter on the garmin gpsmap.

JABS · 03 March 2010, 10:31

Provided it is understood that it is of very limited use.

Yes, I use the voltage readout for the same purpose.

Just be sure to realise that capacity goes from full to almost empty over less than a volt.

chewy · 03 March 2010, 10:35

Quote:

Originally Posted by JABS

Provided it is understood that it is of very limited use.

Its a voltmeter that tells you what voltage is in the battery, what else do you want it to do?

JABS · 03 March 2010, 11:28

My point is that a fully charged battery is 12.6 to 12.8 volts, an almost discharged battery is 12.3.

A 0 to 12 v voltmeter isn't going to tell you a lot.

As mentioned earlier, it will tell you is it is being charged, but doesn't tell you whether the battery is accepting that charge.

If you want to know what is in your battery, you need a more sophisticated piece of kit!

doggypaddle · 03 March 2010, 13:37

Quote:

Originally Posted by JABS

My point is that a fully charged battery is 12.6 to 12.8 volts, an almost discharged battery is 12.3.

A 0 to 12 v voltmeter isn't going to tell you a lot.

As mentioned earlier, it will tell you is it is being charged, but doesn't tell you whether the battery is accepting that charge.

If you want to know what is in your battery, you need a more sophisticated piece of kit!

On the contrary an accurate voltmeter can tell you almost everything you need to know whilst underway! for example while you state the voltages for fully charged battery are correct, what if your voltmeter reads 12.5 volts when underway, well you know your charging system isnt working, likewise if it goes over 14.8 its likely overcharging, also while at rest you can use it as an indication of wether the engine will start after leaving lights or GPS on. also in conjunction with a hydrometer for flooded wet cells can be a good indication of a failing cell before it becomes a problem,
sure its a small voltage change but thats why voltmeters for batteries tend to have expanded scales (analogue ones) that start reading at 12 volts and FSD is 15 volts, with the green band indicating a healthy alternator between 13.5-14.4 volts. For a deep cycle battery the on load voltage change between charged and flat is 25%.
also theyre good for filling up holes in the console where you used to have a useless yamaha trim gauge

JABS · 03 March 2010, 16:15

Yes, agreed. The problem is that some people, obviously not the intelligent variety who populate this forum, think 12v is full and that 0 v is empty.

Yes, an expanded scale type is very useful, but no substitute for a device which actually measures capacity.

I thought most sounders and chart plotters had a voltage read out which is infinitely more accurate that a voltmeter.

I really can't see carrying a hydrometer on board and I hope most of us use sealed lead acid anyway!

chewy · 03 March 2010, 17:29

Quote:

Originally Posted by JABS

Yes, agreed. The problem is that some people, obviously not the intelligent variety who populate this forum, think 12v is full and that 0 v is empty.

It would be fairer to say the less techinally minded than not intelligent.

doggypaddle · 03 March 2010, 17:38

Quote:

Originally Posted by chewy

It would be fairer to say the less techinally minded than not intelligent.

inline....Academic inteligence, technical inteligence and common sense are three quite different things! I know quite a few academically brilliant scientists with very little common sense, and an equal amount of brilliant managers with zero technical knowledge.