Multimeter Calibration?

[BFL13]

What is the best way to check your voltmeter?

Some years ago I ran into the problem where the meter read voltages too high when its battery was low. That took a while to discover since it happened gradually.

Now I found my meter has been reading low for an unknown time. Kept seeing a difference of about 0.2 volts between Trimetric and other meters but thought it was those other meters that were reading high for some reason like voltage drop that confuses things. Anyway, I finally decided that there was something wrong with the multimeter.

Battery ok, fuse ok, leads ok confirmed by swapping them. No change.

Got a new meter and the manual says to first check its voltage to make sure it is working right. Ha! Check it against what?

It is reading about the same as the Trimetric and the other meters, so they seem to have voted on it, and sort of agree on the actual voltage within a 0.1 range.

ISTR on here there was a way to confirm your meter's voltage using flashlight batteries or whatever it was. However, I also remember those eBay meters that are only accurate at higher voltages and are wonky at low voltages.

So what can an RVer do "trying this at home" without having a calibration lab?

[dieseltruckdriv]

Thermoguy wrote:
I knew that when I posted it. Just a good meter for around $100. But, there are others, I have a $400 meter so I'm not going to spend the time to find a link to a cost effective good brand meter that measures DC current. By all means, if you have one, please post for others.

I was just letting people know as well.

This meter doesn't look too bad, but I have no experience with it.

[Thermoguy]

I knew that when I posted it. Just a good meter for around $100. But, there are others, I have a $400 meter so I'm not going to spend the time to find a link to a cost effective good brand meter that measures DC current. By all means, if you have one, please post for others.

[dieseltruckdriv]

Thermoguy wrote:
All meters, thermometers, etc have an accuracy rating. A good meter is +/- 1% or +/-2% of the reading. If you take 2 meters and read the same thing and both are accurate to +/- 2% you can now be off by as much as 4%, so best to not compare 2 meters. The best reading is one that is consistent, meaning if I am reading something and come back tomorrow to read the same measurement, it is within that accuracy rating.

Another point is that all of these meters, Fluke, anyone, are made in China. Better companies use the better manufacturers over there and have better QC. So, it makes sense to buy a better meter if you want better accuracy. A $25 meter is going to give you what you paid for, a cheap meter reading. You should buy a better meter. You can get a descent quality meter for less money than you think. Just search around for it. Stick with a company that makes meters and measuring devices and not some brand that has there label put on a Chinese POS.

This is a great Fluke meter used by lots of electricians at only $100...

https://www.amazon.com/Fluke-Electrical-Voltage-Continuity-Current/dp/B0006Z3GZU/ref=sr_1_5?keywords=fluke+multimeter&qid=1581182098&sr=8-5

There are other good manufacturers of meters that are comparable and probably a little less expensive.

The meter you linked to would be ok to test a pedestal, but not good for dc. We got them at work and I told them I don't even want one. I put it on 12 power supply, and it only gave the reading in volts. As in 11. I like to see hundredths of a volt at work. I do controls stuff, and when I am measuring 4-20 milliamps, it matters. That meter only does AC when measuring amps. I am not saying it is a bad choice, just be aware it is just very limited on DC stuff.

[Tom_M1]

Thermoguy wrote:
This is a great Fluke meter used by lots of electricians at only $100...

https://www.amazon.com/Fluke-Electrical-Voltage-Continuity-Current/dp/B0006Z3GZU/ref=sr_1_5?keywords=fluke+multimeter&qid=1581182098&sr=8-5

This meter does not measure DC current. A better choice for RV use would be one that also measures DC current.

[BrianinMichigan]

.2 volts and .01 volts. unless your adjusting a bias circuit, you should be happy with that. Back in the day the RCA Senior Volt ohmist was the standard. now my Fluke and my old B&K are the ones to go to. But testing the home A/C voltage they are off from each other by 2 volts. Good enought!

[Thermoguy]

All meters, thermometers, etc have an accuracy rating. A good meter is +/- 1% or +/-2% of the reading. If you take 2 meters and read the same thing and both are accurate to +/- 2% you can now be off by as much as 4%, so best to not compare 2 meters. The best reading is one that is consistent, meaning if I am reading something and come back tomorrow to read the same measurement, it is within that accuracy rating.

Another point is that all of these meters, Fluke, anyone, are made in China. Better companies use the better manufacturers over there and have better QC. So, it makes sense to buy a better meter if you want better accuracy. A $25 meter is going to give you what you paid for, a cheap meter reading. You should buy a better meter. You can get a descent quality meter for less money than you think. Just search around for it. Stick with a company that makes meters and measuring devices and not some brand that has there label put on a Chinese POS.

This is a great Fluke meter used by lots of electricians at only $100...

https://www.amazon.com/Fluke-Electrical-Voltage-Continuity-Current/dp/B0006Z3GZU/ref=sr_1_5?keywords=fluke+multimeter&qid=1581182098&sr=8-5

There are other good manufacturers of meters that are comparable and probably a little less expensive.

[wa8yxm]

theoldwizard1 wrote:

wa8yxm wrote:
In days of old when folks were bold I had a VTVM ...

You must be close to MY age !

Simpson 260, Tek 555 (half hour warm up time and a great and warmer), ...

Though I'm not on the Internet I'm 70.. (I never give my true age for security reasons but.. Well. close)

[Gjac]

theoldwizard1 wrote:

Gjac wrote:
If you have a HF mulimeter there is a pot inside that will adjust the voltage readings. I use my B&D charger and adjust the voltage reading on my HF meter to match it. I have about 4 meters that I use in the RV,house and car now that all read the same now.

Good start, but there is no guarantee that they will stay in sync across the whole range.

If you work in an electronics lab, there are two classifications of equipment; "estimate only" and "calibrated", typically once a year.

Your right, I tested mine at a lower voltage and it was off .01 volts, so I calibrate mine for my battery voltage 12 + volts. To send my meters out for calibration would cost more than my meters are worth, so to monitor battery voltage it is good enough. If I worked as an electronic technician and needed an accurate meter everyday for my job I would buy a Fluke.

[theoldwizard1]

Gjac wrote:
If you have a HF mulimeter there is a pot inside that will adjust the voltage readings. I use my B&D charger and adjust the voltage reading on my HF meter to match it. I have about 4 meters that I use in the RV,house and car now that all read the same now.

Good start, but there is no guarantee that they will stay in sync across the whole range.

If you work in an electronics lab, there are two classifications of equipment; "estimate only" and "calibrated", typically once a year.

[theoldwizard1]

wa8yxm wrote:
In days of old when folks were bold I had a VTVM ...

You must be close to MY age !

Simpson 260, Tek 555 (half hour warm up time and a great and warmer), ...

[dieseltruckdriv]

I know this won't really help you, but at work we used to send our meters in to Fluke for recalibration. Then I would check my meters (Flukes) against the newly calibrated meter.
This year they decided the cost was too high, so they just bought us new meters.
My old Fluke 77 and my favorite, a 73 still match the new meter, so I am still good. I typically test with 12V, 24V, 120VAC and 240VAC. That covers my useage.

Actually, if you know of someone with a decent adjustable power supply, you could test your meter against that. I know mine is within 1/100th of a volt. That is good enough for my camper. 😉

[BFL13]

Gjac wrote:
If you have a HF mulimeter there is a pot inside that will adjust the voltage readings. I use my B&D charger and adjust the voltage reading on my HF meter to match it. I have about 4 meters that I use in the RV,house and car now that all read the same now. I used to use my friends Fluke meter to adjust my HF meter but he moved away.

Never thought of that! VEC1093DBD on a battery the meter said is 13.14, the VEC said 13.2v. That was with it clamped to that battery and plugged in saying 000 but not set to charging.

This was in the unheated garage. The VEC has temp comp voltage.

[Gjac]

If you have a HF mulimeter there is a pot inside that will adjust the voltage readings. I use my B&D charger and adjust the voltage reading on my HF meter to match it. I have about 4 meters that I use in the RV,house and car now that all read the same now. I used to use my friends Fluke meter to adjust my HF meter but he moved away.

[wa8yxm]

In days of old when folks were bold I had a VTVM As I recall a RCA Voltomist or something like that A fresh carbon zinc dry cell is 1.06 V according to the instruction manual I just downloaded (NOTE My Memory is .... Different)

Full calibration you really need an electronics lab but I normally go with multiple meters if they all agree.. GOOD. if all but one agrees. That one needs attention.