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Old 27-07-2009, 22:58   #46
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HelloSailor: what's "outside calibration"?? I think what they mean is that you send in the meter and get it back checked, calibrated and certified. Auto-calibration is never certified of course, it's just a feature of the meter and only as good as it's internal reference. For certification, the adjustment of the reference is checked and the certification is only valid for a certain period, like one year. For cruisers, the initial adjustment and quality of a Fluke is more than enough. When you want to check heart rate monitors or the triggers of nukes, you need the certificate.

A decent meter has a good & stable internal reference, let's say 1V. The meter measures that and calibrates itself to show 1V. This is done during the delay when you switch it on, also, a self diagnostic is performed.

Fluke doesn't mention this because every decent meter does it. It simple really, just compare the price & feature set. A $20 DMM that does DC & AC voltage and current plus resistance doesn't compare to a $150 Fluke that does the same. Same for a $150 DMM that can even do capacitance, transistor check and the lot (it's not a good meter I mean). Cheap meters are cheating meters; many even show wrong readings when the internal battery gets emptier, temperature changes etc. Good meters have a stable internal reference that copes with all that. This means more expensive components and more of them.

Buy the basic Fluke like the 113. It does a lot incl. auto ranging and that nifty low impedance measurement that shows the voltage between 2 points when measuring resistance (for checking alternator diodes etc.) When you do a lot of AC, get the 114 which adds true RMS measurements. The only thing you can need that they don't have is a current-clamp. I think the Fluke offering on clamps is too expensive (it's not accurate enough to charge that much imo) so I just bought this sperry meter instead: Amazon.com: A.W. Sperry DSA500A 5-Function 9-Range 400-Ampere Digital Clamp Meter: Home Improvement
Make sure the clamp meter can do DC amps as most are AC amps only!

For $200 you have everything you need... well besides a pocket oscilloscope that is, but hey you must be an electronics geek before you can use these (but you need it when you want to check the Danfoss controller/inverter etc. ;-)

I have had many cruisers coming over to ask me why their AC aboard is just 80V and how is it possible that everything still works. I give them a bit of a bad time, get my Fluke out and show them it really is 120V but their $20 mickey mouse meter doesn't realize it's supposed to work in the tropics too. Or they ask me to "calibrate resistance" because they can't adjust it to 0 Ohm when connecting the two leads... well leads is a big word for the plastic cord that's better suited for drying the laundry on. Switch on Fluke, put the test leads together: 0.0 Ohms. When you are in trouble and get out the meter to see what's wrong, you want to find out what's wrong with the boat, not what's wrong with the meter.

A Fluke meter is like Mitutoyo calipers: you use it for the rest of your life when you don't lend it out....

cheers,
Nick.
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Old 28-07-2009, 02:34   #47
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Gotta say I'm with S/V J on the Fluke meters.

Mine is coming up to the 20 year mark soon; gets used every week and is still good.

Yes I get it re-certified every two years but never had a problem with it. Of course I have the advantage of being able to do the calibration in house but regardless of that, it has only ever needed a very slight tweak once or twice.
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Old 28-07-2009, 07:05   #48
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Thanks, Nick. Someone (was it you?) had suggested Extech DC-400 DC Mini Clamp Meters, Extech DC400 - at the Test Equipment Depot for possibly the cheapest clamp-on that will do DC current, at $80+s&h. One of these days, I'll get some kind of clamp on, right now I make do with borrowing a (not Fluke<G>) from a friend.

Had a real nice Fluke-quality B&K multimeter from possibly the late 70's...but made a small oopsy and fried it some years ago, so I use a pair of less expensive dmm's for now. A Fluke is also on my list...but you know, there's always something "needing" more. Like the time I had some mysteries in the car and finally bought a oscope simply because there are no shops that know how to USE scopes on cars any more, and they just aren't optional for some things. Waited around to find a nice clean use Tektronics for that, the folks at Tek don't care who you are or how old the scope is, they answer the phone and make you feel like family. (Hardly a "boat" vendor", but still one for the short list!)

Isn't the Fluke "low voltage" resistance test range essentially the same as the diode test range on most dmms? i.e. a resistance test designed to stay below the trigger threshold?

I notice that even on eBay, Fluke meters either go high, or always have a little note like "replaced $24 worth of fuses" (with no mention of why) or "works great except for xxx scales". Maybe I'll cruise the pawn shops instead.
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Old 28-07-2009, 07:22   #49
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Quote:
Originally Posted by hellosailor View Post
.......
Isn't the Fluke "low voltage" resistance test range essentially the same as the diode test range on most dmms? i.e. a resistance test designed to stay below the trigger threshold?.....
OK, I am NOT a Fluke expert but I understand the the resistance test range on a Fluke certainly uses a voltage that is below the forward bias voltage of a semi-conductor junction while the diode test range MUST use a voltage higher than this.

Again I understand the Fluke actually uses a constant current source when using the diode test function so that the reading you get when a diode is forward biased is the voltage drop across that junction rather then the "resistance" of that junction.
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Old 28-07-2009, 07:38   #50
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Canadian Tire has a AC/DC Digital Clamp Multi-Meter, Product #52-0163-8, on sale for $20.99.

Iíve never used this meter, so cannot comment on quality (wonít be high), but Iíve never seen a DC Clamp-On Ammeter this cheap.
I'd certainly buy one, if I had any use for it, and didn't already have several.

Digital Clap Meter | Canadian Tire
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Old 28-07-2009, 07:52   #51
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Canadian Tire has a AC/DC Digital Clamp Multi-Meter, Product #52-0163-8, on sale for $20.99.

Iíve never used this meter, so cannot comment on quality (wonít be high), but Iíve never seen a DC Clamp-On Ammeter this cheap.
I'd certainly buy one, if I had any use for it, and didn't already have several.

Digital Clap Meter | Canadian Tire
So I should ask Canadian Tire what exactly does a "Clap Meter" do? Does it meter the clap of thunder, clap of a hand, or perhaps the kind of clap that hits the unprotected sailors of the navy when they hit port?
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Old 28-07-2009, 09:40   #52
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All those electronic meters for measuring how much you have used and how you used them are great BUT they will never tell you how messed up or degraded your batteries are.


If you have a 100 AmpHr battery that is partially sulphated or whatever a test of it capacity is the only way to really know beyond any doubt.

In Battery Lingo the AmpHr Rating of a battery is its 20 Hour Rate.

100 ampHr rating in battery lingo means the battery will be dead in 20 hours at rate of 5 Amps.

200 ampHr rating means it is dead in 20 hrs at 10 amps.

This means at 10 hours at 5 amps a new fully charged 100 ampHr battery will be Ĺ charged. Let it rest with no loads on it for a couple of hours and it should read 12.10 volts. You do need a calibrated voltmeter not one of those Micky Mouse deals. You could use one of those density measurement devices. The problem is stratification of the acid, dense on the bottom and thin on top.

So if you had that 100 ampHr battery and after 10 hrs at 5 amps, and then waiting a couple hours the voltage is 11.96 volts means 40% remaining. This means what used to be 100 AmpHr battery is now a 80 ampHr battery. You have lost 20% of its capacity.


Does that make sense?
OTOH, if you measured both the amp-hours out, and battery voltage as a function of time, you could make a meaningful statement about the state of the batteries. In the good battery case you would have an indication of % out and know when you should run the generator to preserve the batt's. In a bad battery case you would get advance warning of the declining performance and so be better able to decide when to replace them.

I've been thinking about building such a system (being an electronics tinkerer). If so, would anyone buy it?
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Old 28-07-2009, 12:38   #53
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So I should ask Canadian Tire what exactly does a "Clap Meter" do? Does it meter the clap of thunder, clap of a hand, or perhaps the kind of clap that hits the unprotected sailors of the navy when they hit port?
YES - all 3!
What a breakthrough - on a par with the combination screw-driver & hammer multi-tool.

It’s about time we had a cheap meter to monitor this (gonorrhea, or 'the clap') SDS, and measure DC Amps, Sound Levels (with appropriate adapter) and etc.

Our poor unfortunate non-Canadiian members might wonder why we Canucks seem to refer to Canadian Tire (CTC) so much. It's a combination Pep Boys, Home Depot, Wallmart retail store.
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Old 28-07-2009, 14:11   #54
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Zener diodes work great as a reference voltage.
A zener diode by it self will not let you calibrate a voltmeter it require to be part of a circuit.

Now that we are really into multimeter and that we have tenors and pundits into it, I think everything regarding multimeter in this thread could be shifted to a new thread ďMultimeter, shunt and accuracy.Ē And investigate also shunts and battery management accuracy.
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Old 28-07-2009, 16:03   #55
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DC clamp-on meters: they are never really accurate (good ones 1A accuracy) plus on a boat we don't really need more accurate measurements because we use it on big wires/cables like at the battery banks, shunt (yes I check them often ;-) or alternators. But the whole thing must be sturdy enough because a 4/0 cable might not be very willing to be clamped resulting in abuse of the clamp. The Sperry meter holds up very well and isn't too expensive. I even think it's other functions (using test leads) are decent enough for boat work and I often just grab the first one I see.

cheers,
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Old 02-08-2009, 07:54   #56
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DC clamp-on meters: they are never really accurate (good ones 1A accuracy)
With an AC or DC tong testers (see what people come up with) you can amplify the reading. 0.8A for example, can be amplified by 5 to become a reading of 4 and give you a greater accuracy.

Fluke
Nick I was expecting you to said Fluke, Philips, thatís Dutch.
I used to own a DMM whoís advertising was ďour accuracy is no flukeĒ
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Old 02-08-2009, 10:59   #57
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Canadian Tire has a AC/DC Digital Clamp Multi-Meter, Product #52-0163-8, on sale for $20.99.

Iíve never used this meter, so cannot comment on quality (wonít be high), but Iíve never seen a DC Clamp-On Ammeter this cheap.
I'd certainly buy one, if I had any use for it, and didn't already have several.

Digital Clap Meter | Canadian Tire
Gord, it is $59.99 today, not $20.99. Although there's still no picture and damned little information. But since THEY list it as a "Clap" meter, I'd have to wonder if the 400A AC/DC is also another typo.
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Old 02-08-2009, 12:01   #58
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Gord, it is $59.99 today, not $20.99. Although there's still no picture and damned little information. But since THEY list it as a "Clap" meter, I'd have to wonder if the 400A AC/DC is also another typo.
Yep, sale ended July 31.
The meter itself & it's packaging described it correctly.
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