Voltage display offset?

9D280 · 13 March 2012, 15:51

I have been mucking ablut with my new (to me) Lowrance plotter, and having set the display up to show voltage, I thought it looked low. I then compared the battery to the display. Needless to say due to the batt terminals, main switch, fuse, plotter power switch , connector on the back of the plotter & a couple of yards of assorted cable, the display is reading about 0.5V lower than the batt.

After much mucking about deep diving every menu I could find, the only way I could figure out to have an "at battery" readout was to set the voltage display to "bar graph" and alter the parameters to make it turn red / green / yellow at appropriate voltages as offset by my voltmeter reading at the battery. Thing is the bar graph only shrinks in physical size so far, and even at "minimum" takes up more of the display area than I really wanted it to.

I can't find an "offset" option to make the plotter show what I know is happening at the battery, so I get a nice small font number in the corner. Does such a feature exist? if so, what weird combo of keys do I need to press to get it?

jyasaki · 14 March 2012, 01:41

I've found the Lowrance displays to be nicely customizable, but only to a point. You're likely stuck with what they give you, but if you find differently (maybe a call to Lowrance?) I'd love to hear about it.

I noticed the voltage differential as well, and considered addig a small voltmeter wired directly to the battery. Yet another thing I haven't got around to addressing.

jky

9D280 · 14 March 2012, 09:12

I also toyed with that (also means it's independant of plotter electronics & potential failures there) but as I'm already having to build a pod to take the instrumentation I have already, another dial is going to take up more space I don't have...

The annoying thing is that I can make the bar graph do pretty much what I want, but can't customise the digital readout!

Erin · 14 March 2012, 17:41

I suppose it begs the question, are you really that interested with the voltage at the battery terminals, or is the voltage at the ends of the wires connected to your gadgets actually not more relevant? If your battery is 12v but you only get 10v at your equipment due to corossion or wire lengths, I would have thought that that was more important to know.

9D280 · 15 March 2012, 13:18

True, but as most of my "toys" don't have built in voltmeters, what;s happening at source is probably more useful.

It did strike me that setting an alarm to the "modified" voltages and not really caring what was going on minute by minute is probably the most sensible thing. That way if it stops charging or over charges (gubbed regulator) I get a sqeal. At other times I get a nice clear screen.

jezza2011 · 15 March 2012, 13:25

Why not just stick one of these in the Dash?

NEW 2" 52MM BLUE LED DIGITAL TURBO VOLT VOLTMETER GAUGE FOR CAR | eBay

I am thinking fo doing it

Poly · 15 March 2012, 14:59

9d280...

... you've always struck me as a fairly intelligent chap ...

So if I get this right battery on / engine off you are expecting something like 12.7 V but it reads 12.2 .... with the engine on you expect something like 14V but it reads 13.5V

YOU know the 0.5V offset. Can you not mentally apply it or reset your expectations?

Seems easier than trying to get a lowrance plotter to do anything you want that is not explicit in the manual.

9D280 · 16 March 2012, 12:45

I spend all s*dding week doing maths.....

Joking aside, I know I can do that. I have since reconfiguired it to just beep at me if things to totally pear shaped. Keeps the screen clear as well.

I just think it's crazy that I have oodles of computing power at my fingertips that can hook up to dozens of calibratable sensors and the one that can't be calibrated is the one that every person who buys one can use 'coz it's built in!

But then most people probably wouldn't have noticed the differential in the first place....

BumbleAbout · 16 March 2012, 16:13

I agree with earlier posters that the voltage of interest should be that available to your console instruments/ radio - if that requires a heavier duty cable between battery/ isolator and console to reduce the voltage drop then so be it (I doubt that the battery terminals/ isolator/ fuse will contribute much resistance and if they are then worth changing them)!

jyasaki · 17 March 2012, 21:17

Quote:

Originally Posted by Polwart

So if I get this right battery on / engine off you are expecting something like 12.7 V but it reads 12.2 .... with the engine on you expect something like 14V but it reads 13.5V

YOU know the 0.5V offset. Can you not mentally apply it or reset your expectations?

Problem occurs when you've got, say 11V at the plotter (after the electrons have wended their way down the little obstacle-filled copper pathways); what's happening at the electron parking lot? 12.2 (or 14.4 while running) volts would immediately indicate something's wrong with the wiring, and the rest of the electrical system is fine. 11.5 volts would mean it's time to cut the trip short, and perhaps call to make sure assistance is standing by.

jky

9D280 · 19 March 2012, 11:59

Indeed, all are valid arguments.

My engine is self suistaining - if the battery explodes (granted I have a bigger problem than worrying about the actual voltage at the plotter), the engine will keep going. I have a Garmin handheld that will instantly switch to internal battery power, and a handheld VHF in the seat.

A lot of this is as I said above - I can calibrate any one of a number of sensors, but not the built - in one!

Having said that Jezza2012 has solved the problem nicely in the bits'n'pieces section and soon I will have a voltmeter across the battery -ve and swtched side of the main isolator. Main problem now is the finding the console space to mount it!