How to calibrate a voltage meter - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 


Like Tree4Likes
Reply
 
LinkBack Thread Tools
  #1  
Old 06-01-2012
davidpm's Avatar
Senior Member
 
Join Date: Oct 2007
Location: Madison
Posts: 3,675
Thanks: 165
Thanked 37 Times in 30 Posts
Rep Power: 7
davidpm is on a distinguished road
How to calibrate a voltage meter

Some regulars have mentioned calibrating a voltage meter. This sounds like a good idea.
Are there any easily accessible calibrated voltage sources?
I could just stop some random pole worker and ask him it check a battery I carry with me with his fluke then check the same battery with my meter.
In fact I did this with the local auto-parts store. They had a several hundred dollar tester but still how do I know their equipment is in spec.
Reply With Quote Share with Facebook
  #2  
Old 06-01-2012
SchockT's Avatar
Senior Member
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,411
Thanks: 1
Thanked 26 Times in 24 Posts
Rep Power: 3
SchockT is on a distinguished road
Re: How to calibrate a voltage meter

The only way to really test it would be to have a known voltage source, or to check it with a quality voltmeter. (Most power supplies for electronic devices have accurately regulated output.) I have several Fluke meters, and I have them checked for calibration once in a while, but every time they are bang on.

One of my multimeters lives on my boat: it is a standard part of my onboard tool kit. I have found it very useful over the years, for my own problems as well as helping fellow boaters troubleshoot faults.

Do you have reason to believe your volt meter is reading incorrectly?

Last edited by SchockT; 06-01-2012 at 10:54 PM.
Reply With Quote Share with Facebook
  #3  
Old 06-01-2012
bgeddes's Avatar
Member
 
Join Date: Jul 2010
Posts: 58
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 5
bgeddes is on a distinguished road
Re: How to calibrate a voltage meter

A real calibration will require a comparison to a standard traceable to N.I.S.T., the National Institute of Standards and Testing, Typically done by a lab specializing in this service. Probably overkill for on board testing.

It's been my experience that better meters are more accurate. One example of this is that higher quality meters measure RMS AC voltage instead of average. Most of the time it makes little difference, as you are looking for the presence of absence of power.

I have not compared my $4 Harbor Freight meters to the $500 Flukes but it would make for an interesting comparison.
Reply With Quote Share with Facebook
  #4  
Old 06-01-2012
Senior Member
 
Join Date: Aug 2006
Location: Arlington, VA
Posts: 1,808
Thanks: 0
Thanked 4 Times in 4 Posts
Rep Power: 9
btrayfors will become famous soon enough btrayfors will become famous soon enough
Re: How to calibrate a voltage meter

One simple workaround for meter calibration when you don't have a better alternative is to use fresh alkaline batteries. Here are some voltages as measured with my Fluke 189:

Battery Type Chemistry Voltage

1 D Alkaline 1.5966
2 D Alkaline 1.5979

3 C Alkaline 1.5591
4 C Alkaline 1.6113
5 C Alkaline 1.6104
6 C Alkaline 1.6112
7 C Alkaline 1.6100

8 AA Alkaline 1.5852

9 AAA Alkaline 1.5946

10 9V Alkaline 9.5090
11 9V Alkaline 9.5010

Bill
Reply With Quote Share with Facebook
  #5  
Old 06-02-2012
Ritchard's Avatar
No more curry buffets
 
Join Date: Aug 2011
Location: Toronto
Posts: 379
Thanks: 2
Thanked 5 Times in 5 Posts
Rep Power: 4
Ritchard is on a distinguished road
Re: How to calibrate a voltage meter

I would go Bill's test above one further. Gather up an good sampling of multitesters from the boats around you, and test them all. You should then get a good set of averages from which to spot variance. This will give you some sense of whether your meter is close enough. And for pretty well everything on the boat, close enough is close enough.
__________________
Bashing about on Lake Ontario and Beyond
"Ariel" '79 Endeavour 32
Reply With Quote Share with Facebook
  #6  
Old 06-02-2012
tommays's Avatar
Senior Member
 
Join Date: Sep 2008
Posts: 4,234
Thanks: 1
Thanked 24 Times in 24 Posts
Rep Power: 6
tommays will become famous soon enough
Re: How to calibrate a voltage meter

I have a high end Fluke that gets yearly certs used in pharmaceutic for IO ,OQ , PQ validations and the FREE harbor freight meter gives the SAME results on 12 volt DC
davidpm likes this.
__________________
1970 Cal 29 Sea Fever

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

1981 J24 Tangent 2930
Tommays
Northport NY


If a dirty bottom slows you down what do you think it does to your boat
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #7  
Old 06-03-2012
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,533
Thanks: 2
Thanked 82 Times in 80 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: How to calibrate a voltage meter

Fresh batteries, ah, such mythological creatures.

In theory coin cells holde ven tighter tolerances but those can vary as well.

I cheated. I bought some precision voltage reference chips, which are designed to take roughly 8-20V input and put out 10.00v. They may float by a couple of digits in the THIRD decimal place, but with a 4-digit meter that means 10.00 is damn well 10.00, exact to the last digit.

Then I opted for "small" and wired them up to small 12V batteries, in holders, with a power switch and a couple of alligator leads instead of terminal posts. The hardest part of the assembly was obtaining the Altoids mini-tin, because yes, it lives in a small Altoids box. About three bucks cheaper than the smallest "professional" case I could find.

Of course that's just me, I decided to build a proper tool so I can calibrate anything I want for years to come. No, it isn't NTST calibration, but from what I've read when these chips say "10.00" that's a Real Damn Sure 10.00 and I can't ask more than that, especially for maybe $20 worth of parts. I'm sure if there was a market I could job 'em out to China for under $10 each, landed.

Once you have a calibration source of whatever kind you are going to use, you take the back off the meter and look around. You may need to check the manual or ask the maker, but typically there are one or two small screwdriver-adjusted trimpots inside. If there's only one, mark the position it is in, then while the meter is connected to the calibration souce, SLOWLY trim that screw until the voltage matches the source.

If there is more than one trimpot, congratulations, you've got a better meter. Try not to mess with the wrong one. (Which is why you mark it, and check with the maker.)

After calibrating, but the back on the meter again, check calibration again. Sometimes it slips a bit during the final handling and you need to do it again.

Harbor Freight? ROFL, my little HF's were worth what I didn't pay for them, but they are more light test lamps than real meters. Wooboy do they vary.
Reply With Quote Share with Facebook
  #8  
Old 06-03-2012
Junior Member
 
Join Date: Sep 2000
Location: Where the anchor is set.
Posts: 19
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
jentine is on a distinguished road
Re: How to calibrate a voltage meter

What is so critical that you require a calibrated volt meter. Most of the jobs on a boat merely require a test light. Either you have power or you don't.

Jim
dacap06 and travlineasy like this.
Reply With Quote Share with Facebook
  #9  
Old 06-03-2012
travlineasy's Avatar
Morgan 33 O.I. Perryville
 
Join Date: Dec 2010
Location: Maryland
Posts: 2,266
Thanks: 3
Thanked 55 Times in 45 Posts
Rep Power: 4
travlineasy will become famous soon enough
Re: How to calibrate a voltage meter

Checking voltages, continuity, trouble-shoot electrical problems, etc... on boats isn't rocket science. You REALLY don't need anything better than an El-cheapo from Harbor Freight--it will do much more than most boat owners and mechanics can fathom. And, it will do them very accurately for years and years, and years. Many, many years ago I had some really expensive electronic testing equipment--it's all outdated and pretty much worthless--especially in the world of recreational boating.

Good luck,

Gary

Last edited by travlineasy; 06-03-2012 at 11:51 PM.
Reply With Quote Share with Facebook
  #10  
Old 06-04-2012
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,533
Thanks: 2
Thanked 82 Times in 80 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: How to calibrate a voltage meter

I would argue that if you want to know what your electrical system is doing, a calibrated meter is necessary. Is your alternator putting out 14.2 when it should be putting out 14.4 (in a modern well regulated design) ? Or is it putting out 14.6 with regulator failure to come?

Is your battery charged to 12.4, and down 20% capacity? Or is it 12.6 and really full?

Is it being charged to the proper voltage points at all? Or, again, 20% off?

Are you deep cycling your batteries to the 30% point where they may get 1000 cycles? Or the 50% point where they may get only 300 cycles?

In all cases the difference is only 2/10ths of a volt, and an uncalibrated untested meter cannot be assumed to be any more accurate than that. But a calibrated meter can almost give you as much information as an expensive battery charge monitor. As well as confirming the charge monitor is working correctly.

The el-cheapo from Harbor Freight? I had one that was more than 1/2 volt off when new. I need more than something which tells me the whole electrical system has failed--when it hasn't. The reliability and consistancy of HF products is well known. Doesn't make them a total waste all the time, but they need to be used in context.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 2 (0 members and 2 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Re: Digital Voltage Meter NewsReader Mass Bay Sailors 0 03-19-2007 11:15 PM
Re: Digital Voltage Meter NewsReader Mass Bay Sailors 0 03-19-2007 11:15 PM
Re: Digital Voltage Meter - re: Blue Sea Model 8251 with alarm NewsReader Mass Bay Sailors 0 03-19-2007 07:15 PM
Some answers to my own Digital Voltage Meter questions NewsReader Mass Bay Sailors 0 03-19-2007 02:15 PM
Digital Voltage Meter NewsReader Mass Bay Sailors 0 03-19-2007 12:15 PM


All times are GMT -4. The time now is 07:54 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.