3 different volt readings? Time for a new meter?

[ericfx1984]

Okay.. here's the deal I have three different voltages

NOTE: I am considering purchasing a FLUKE 101

When testing a bank of lifepo4 batteries in parallel I get different readings

For instance my trustee old Amprobe ACD-15 TRMS Pro reads 3.557

My harbor freight special freebie reads 3.60v

And then my Amazon bench power supply reads 3.62v.. but with no load on it, and reading directly off of the outputs my Amprobe multimeter reads 3.65v

If I read a brand new AAA alkaline battery the amprobe meter reads 1.606v while the harbor freight special reads 1.62v

Well these are not huge differences they are differences nonetheless. And honestly the difference is pretty incredible when you consider the fact that the voltages are so low, in short it's a very high percentage of difference

Normally my thought would be to trust the amprobe.. it has higher quality leads and is a better built unit overall ... But it's had the crap beat out of it over the years

 

[HRTKD]

If you want to know if your meters are out of spec, there are devices that you can test the meters against.

voltagestandard.com

low cost, battery operated, precision DC voltage references from 2.048V to 10V

voltagestandard.com

I bought one of these a couple years ago and found that my meters were close enough for my uses. But it does sound like you have a meter that deviates enough from the other two that I would suspect it is out of spec.

As far as buying a new meter goes, consider spending the extra money on one with a clamp on DC ammeter. Knowing the amps flowing through a cable can be quite helpful for troubleshooting. I have a Fluke 325. It has been very helpful. I didn't think I would ever use the temperature feature but it sure came in handy when I was setting up the warming system on my batteries. Without it, I wouldn't have known that the thermostat provided by the vendor was flawed. My only complaint about the 325 is that there isn't enough precision. Another decimal place would be helpful.

 

[jberger]

Tons of tests, reviews, feedback etc. over at EEVBlog.
If you are shopping, I'd start by looking at the forums over there.

Test Equipment - Page 1

Test Equipment - Page 1

www.eevblog.com

 

[Diysolar123]

if you are not worried about microvolt errors just snag an AD584 voltage ref from ebay and that way you can have some degree of confidence in your meter. as mentioned above eevblog is a great source of info on the technical side of electronics when it comes to meters; here is an old multimeter video that is still applicable today hehe

 

[WYtreasure]

I ran in circles for an hour "one time" with a similar problem, multiple volts at the same wire, with a Meterman 33XR. Turned out the batteries/battery was low. ? Ever since that day, when my meter starts goin whacky I check the battery.

 

[pollenface]

I trust my fluke with my life

 

[efficientPV]

You should only own one clock and one meter if you want to sleep at night.

 

[alfsauve]

Confucius say man who own one thermometer (meter) know exact temperature. Man who own six never sure.

 

[Substrate]

The 101 would be an improvement for sure, but if you are going to go Fluke, then I recommend considering the 11x series at a minimum, not the 100 series.

I have a 101, and while cute for a Fluke, it is a pocket meter. The leads come out of the bottom. The small size and leads out the bottom make it a pita to stand or put anywhere.

The other consideration is that the 11x series at least has the min/max function with audible beeps when the voltage changes.

You know the deal - with LFP, you are in the flat part of the knee most of the time while charging. The fluke's min/max beeps being audible, means that if you get distracted, and your pack hits the upper knee and skyrockets, the 11x series will grab your attention pretty quick, whereas the 101 won't.

Just saying - there are many good quality meters other than Fluke - but if you are going to go this route, don't be tempted to go to the bottom end. As cute as it is, the 101 is still a pocket-meter with limitations. The 11x or higher is the way to go.

 

[Al D]

Okay.. here's the deal I have three different voltages

NOTE: I am considering purchasing a FLUKE 101

When testing a bank of lifepo4 batteries in parallel I get different readings

For instance my trustee old Amprobe ACD-15 TRMS Pro reads 3.557

My harbor freight special freebie reads 3.60v

And then my Amazon bench power supply reads 3.62v.. but with no load on it, and reading directly off of the outputs my Amprobe multimeter reads 3.65v

If I read a brand new AAA alkaline battery the amprobe meter reads 1.606v while the harbor freight special reads 1.62v

Well these are not huge differences they are differences nonetheless. And honestly the difference is pretty incredible when you consider the fact that the voltages are so low, in short it's a very high percentage of difference

Normally my thought would be to trust the amprobe.. it has higher quality leads and is a better built unit overall ... But it's had the crap beat out of it over the years

The meter measuring millivolts would be my choice as it has a higher degree of certainty. However, calibration is critical if you are concerned about such small deltas. Also, I'm not sure what the manufacturers tolerances are on each meter, but I'd go with the one that has the tightest tolerance.

Of course, if you're not in a lab and can't be bothered to stay current with the calibration, you really have no reason to choose one over another as none are warranted to work as accurately as you desire.

Power source and temperature are two big factors that can affect your readings. It looks like your set for a DIY project, otherwise.