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Voltage question..and a pic

Old 07-09-2006, 10:48 AM
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Default Voltage question..and a pic

I asked this on SIM's forum for his expert opinion, but thought I might ask y'all as well. Both gauges are on the same battery (actually, the same power wire/harness that come off the single motor). Any ideas?

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Old 07-09-2006, 10:55 AM
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Default Re: Voltage question..and a pic

dunno - but I have the same sitation with my smartcraft vs my GPSs readings for voltage - off by abouot 2 tenths...rather that figuing it out, I do what I always do best - threw money at the problem - and got one of these which had independant leads directly to each abattery - got it from Andy @ SIM...

http://www.newmarpower.com/digitalin...sturments.html

it is dead on accurate based on using a mutimeter at the batts....
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Old 07-09-2006, 11:04 AM
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Default Re: Voltage question..and a pic

Can't really reverse the plugs; they are special plugs to each gauge.
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Old 07-09-2006, 11:56 AM
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Default RE: Voltage question..and a pic

Joe - 7/9/2006 9:48 AM

I asked this on SIM's forum for his expert opinion, but thought I might ask y'all as well.
Thanks for the vote of confidence !

I'll bet the DMM reads 14.2V. Then change the display & monitor one or the other & stop driving yourself crazy. It's like trying to get SOG, pitot speed & paddlewheel speed all the same. The length of the wire, # of connections, quality of those connections could cause a small voltage drop

Now let's see what Master Andy has to say .......

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Old 07-09-2006, 02:22 PM
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Default RE: Voltage question..and a pic

Elusive - 7/9/2006 11:56 AM

Joe - 7/9/2006 9:48 AM

I asked this on SIM's forum for his expert opinion, but thought I might ask y'all as well.
Thanks for the vote of confidence !

I'll bet the DMM reads 14.2V. Then change the display & monitor one or the other & stop driving yourself crazy. It's like trying to get SOG, pitot speed & paddlewheel speed all the same. The length of the wire, # of connections, quality of those connections could cause a small voltage drop

Now let's see what Master Andy has to say .......
heh..the 14.2 v is pretty much what I thought too. Not really driving me crazy, just has me scratching my head. I was playing with the available displays and accidently saw that i could do this. I wish I hadn't found it now!
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Old 07-09-2006, 02:45 PM
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Default RE: Voltage question..and a pic

Joe - 7/9/2006 12:22 PM
Elusive - 7/9/2006 11:56 AM
Joe - 7/9/2006 9:48 AM I asked this on SIM's forum for his expert opinion, but thought I might ask y'all as well.
Thanks for the vote of confidence ! I'll bet the DMM reads 14.2V. Then change the display & monitor one or the other & stop driving yourself crazy. It's like trying to get SOG, pitot speed & paddlewheel speed all the same. The length of the wire, # of connections, quality of those connections could cause a small voltage drop Now let's see what Master Andy has to say .......
heh..the 14.2 v is pretty much what I thought too. Not really driving me crazy, just has me scratching my head. I was playing with the available displays and accidently saw that i could do this. I wish I hadn't found it now!
I have been some long hard research aboutyour issue and have come up with the conclusion about your problem Joe. You have way to much free time on your hands. My suggestion would be to actually go out and use your boat ............so in turn it will wear out and break............then you have to buy more Yamaha parts from me. [img]../images/emoticons/biggrin.gif[/img][img]../images/emoticons/biggrin.gif[/img]

































Just kiddin of course but I think Gary has an idea about the wire lengths ect. Only thing that makes sense to me.

Andy
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Old 07-09-2006, 02:50 PM
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Default Re: Voltage question..and a pic

I think SIM has the right answer!!!
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Old 07-09-2006, 07:20 PM
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Default Re: Voltage question..and a pic

Joe,

I understand your head scratching as it would keep me occupied also.... If you want to rule out the different wire lengths, you can trace the wires from the instruments back to the source and make an equal length y adaptor to even out the lengths. Also I would make sure the connectors are absolutely perfectly clean and also coat them with di-electric grease.

If they still read differently, I might take a seperate battery and connect it directly to one insturment and then the other instrument to compare them against a DMM reading from that battery. If they read the same I would go back to the wiring and explore further, if they are differnt then it would be simply guage difference.


Then again... I am a perfectionist and I wouldnt stop till I had an explanation, but it wouldnt help me catch more fish!
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Old 07-09-2006, 11:14 PM
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Default Re: Voltage question..and a pic

Voltage meters have tolerances for accuracy. Unless you are talking about lab quality, high end, volt meters, it is not unusual for two of the same type to vary by couple of tenths of a volt. Also, the wiring going from the common connection point to the speed/fuel gauge might have a little more resistance in it that the wiring that goes from the common connection point to the tach.

I bet if you put a good quality digital volt meter directly on the battery you might have a slightly higher voltage than is shown on the tach. Then again, if you measure the voltage at the output of generator it will probably be slightly higher than the voltage at the battery. This is all due to voltage drop in the wiring, which in natural and results from the fact that both wires and their connections have resistance which drops the voltage in a circuit.
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Old 07-10-2006, 01:10 AM
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Default Re: Voltage question..and a pic

Maybe I am wrong but I think 2-tenths of a volt is too much difference. And I don't see Yamaha as a company that would ship cheap made-in-China throw-away parts with their name on them. I think Yamaha will require those gauges be made to within a spec'd tolerance.

SIM / Andy - what is Yamaha's spec for the accuracy of those gauges?
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Old 07-10-2006, 10:24 AM
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My Fluke Model 73 multimeter (I think Fluke is not a cheap made-in-China throw-away part) has an accuracy tolerance of plus or minus .3% and one least significant digit. Oh, this is when new, the accuracy will probably fall off as the instrument ages.

Let's assume that the generator is really providing 14.2 volts to the meter. With the above stated accuracy the meter could read as much as 14.0 volts on the low side (14.2 times 99.7% minus one tenth) or as much as 14.3 volts on the high side (14.2 times 100.3% plus one tenth). Throw in a little more or less resistance in the wiring and the figures seen on Joe's two instruments don't seem unreasonable at all.

Sim has the best idea when he implies that Joe should spend more time boating and less time worrying about the fidelity of his gauges. In the grand scheme of things a couple of tenths of a volt is nothing to be concerned with. Kind of like trying to pick fly sh1t out of the pepper.
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Old 07-10-2006, 01:11 PM
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Default Re: Voltage question..and a pic

Great explanation jethro1,

The way I would fix this problem is by using standard black electrical tape. I would pick the reading I liked best and then cover the other one with the tape!

Problem solved.......now go do some boating!

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Old 07-10-2006, 02:16 PM
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Default Re: Voltage question..and a pic

I wasn't so much worrying about it as I was noting the difference, and scratching my head and wondering "why?". I would worry if they dipped down into the 12-13v range however.
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Old 07-12-2006, 11:25 PM
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Default Re: Voltage question..and a pic

Update:
While doing some "staying out of the house and just fiddling aound" today on the boat, I found that the gauges DO have the same power connectors; so I exchanged them to see what the reading was.

It was the exact same.

Tells me I have a gauge discrepancy..not that I really care.
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Old 07-12-2006, 11:39 PM
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Default Re: Voltage question..and a pic

Tells me I have a gauge discrepancy..not that I really care.
C'mon Joe, you're in denial. Admit it ..................... you do care. In fact it's driving you crazy



Thanks for the update

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Old 07-13-2006, 12:08 AM
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Default Re: Voltage question..and a pic

Joe - 7/12/2006 11:25 AM

Tells me I have a gauge discrepancy..not that I really care.
Yeah, not surprised. Unlike Jethro1, I don’t think .2v is an aceptible margin of error for a pair of voltmeters. And also unlike what Jethro1 wrote above, my Fluke DMM is rated for 0.025% error.

Fwiw, I have the Fluke DMM, an older made-in-Korea DMM that has been calibrated, two different Blue Sea Systems DC digital meters, one each Xantrex and Newmar digital DC meters on board. ALL of those display the exact same voltage to the 10th of a volt on a 24vdc system.

That’s why I would not accept a 2/10 (1/5) volt error between two gauges, especially if they are from the same manufacturer where they should be calibrated similarly. But if you are ok with it, go with it.


WE ARE STILL WAITING FOR SIM / ANDY to respond to the request for the Yamaha spec for the accuracy of your gauges, if he knows. I looked on Yamaha’s webpage but couldn’t find the specs for their digital gauges. No published spec is not good, may be an indication those Yammy gauges may indeed be built from cheap, throw-away parts.
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Old 07-13-2006, 06:23 PM
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Jethro did not say it was acceptable. Jethro said it is what it is.

Jehtro does not design voltmeters and Jethro does not get a say in their accuracy tolerances.

What model Fluke do you have? That is a pretty impressive accuracy rate of error. I looked at Fluke's website and did not see one with that degree of accuracy.

Do you think a gauge on a boat would have the same accuracy tolerance as a meter that is made to test circuits? I don't know, just asking a question.

The problem with digital instrumentation is if you are anal retentive (I am) it can make you go mad. If my engine is operating at 153.2576 degrees I want a gauge to indicate that. Unfortunately, my budget will only allow me a gauge that reads with plus or minus five degrees, and I had to really struggle to get that degree of fidelity. I just had to get over it.

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Old 07-13-2006, 07:14 PM
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Default Re: Voltage question..and a pic

Well I can see this is another thread that I should have just skipped over and never got involved in[img]../images/emoticons/biggrin.gif[/img][img]../images/emoticons/biggrin.gif[/img]

I do not have any idea what the "specs" are for those gauges. And quiet honestly, I don't care andI have better things to do with my time then research that kind ofinfo. There are plenty of O2 sensorsand VST screens that need my immediate attention.[img]../images/emoticons/biggrin.gif[/img]

BTW......I had to follow through and make some Yammie phone calls and ask the"experts"............those two gauges could be pulling battery voltage from two different sources. One from the key switch and the other from the ECM. I think its safe to assume that between those we could have enough different wire lengths and other thingsbetween them to justify the difference. Or maybe Eyeballs hasit right.......Yamaha Command Link gauges are just made from cheap throw away parts. Time will tell with that.

While we are being picky........I am sure Eyeballs 3GPS's displayheadings, magnetic ship compass, autopilot compass and his hand help pocket protector compass all read within a degree of each other while underway. Right? Of course they do. [img]../images/emoticons/thumbsup.gif[/img]And I thought my buddy Joe had to much time on his hands......Phein and Eyeballs bring that to a new level.[img]../images/emoticons/biggrin.gif[/img]

Andy
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Old 07-13-2006, 07:38 PM
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Duct Tape - 7/13/2006 5:33 PM

jethro is not a millionaire sports star. so jethro might not want to talk in the 3rd person about himself
How did you know? Lucky guess I bet.
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Old 07-13-2006, 07:52 PM
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SIM - 7/13/2006 7:14 PM



Well I can see this is another thread that I should have just skipped over and never got involved in [img]../images/emoticons/biggrin.gif[/img][img]../images/emoticons/biggrin.gif[/img]

I do not have any idea what the "specs" are for those gauges. And quiet honestly, I don't care and I have better things to do with my time then research that kind of info. There are plenty of O2 sensors and VST screens that need my immediate attention.[img]../images/emoticons/biggrin.gif[/img]

BTW......I had to follow through and make some Yammie phone calls and ask the"experts"............those two gauges could be pulling battery voltage from two different sources. One from the key switch and the other from the ECM. I think its safe to assume that between those we could have enough different wire lengths and other things between them to justify the difference. Or maybe Eyeballs has it right.......Yamaha Command Link gauges are just made from cheap throw away parts. Time will tell with that.

While we are being picky........I am sure Eyeballs 3 GPS's display headings, magnetic ship compass, autopilot compass and his hand help pocket protector compass all read within a degree of each other while underway. Right? Of course they do. [img]../images/emoticons/thumbsup.gif[/img] And I thought my buddy Joe had to much time on his hands......Phein and Eyeballs bring that to a new level.[img]../images/emoticons/biggrin.gif[/img]

Andy





hahaha No comment here. I should have left well enough alone! As long as it is regsitering..I'm happy
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