These cells are 3.2V. 1% accuracy is 0.032V. Most meters report 0.00V accuracy. .01V accuracy is 0.3% of the measured value.
0.3% accuracy is more than enough. Many meters report .001V, which is 0.03% accuracy on these cells. 5 digits is pretty absurd unless you're engaged in scientific efforts where 5 digits matters. In the case of this forum, it's rare that more than 0.00 digits would be meaningful.
A voltage reference is a name given to a device that supposedly has a very accurate voltage to which meters can be checked and calibrated. Expensive ones are probably pretty accurate. Cheap ones are less so. I bought a cheap one one. When my Fluke read exactly the correct voltage to .000, I was confident the reference was accurate enough to calibrate my other meters to it.
Accuracy | 0.5% + 2 |
Factory, Nice, I will peek at craigslist for used Flukes too,I have a Fluke 87 from the mid-90's that does most of my solar work. It is durable. It is trustworthy. It has literally traveled the planet and worked in all sorts of exotic locations. It was chose for it's reliability and it has delivered. Accuracy - is probably about 10x what is needed for almost all solar related things.
In general, however, you want your measurement instrument to be about 10x higher precision than what you need as a final result so that works out perfectly.
I also have a 6.5 digit Keithley DMM for my lab bench. It is brutally accurate and amazing, but it is also big, heavy, expensive, and requires AC power to work.
The Fluke is great.
RC,For low cost the Uni-T 61E gives 22,000 count (more decimal points) and 0.05% accuracy. They are about $60.
Only negative is they are not super resistant to ESD static discharge damage.
You will typically use DC volts, ohms/continuity, likely AC volts. Having freq is good to check generator's rpm settings. Capacitance is good for AC motors run and start capacitor testing.RC,
I bought this unit, it in the snail mail.
I need 2 hand held units and 4 panel display that just display volts. I want to have a boat bag with the cheapo units, in Michigan stuff tends to walk off truck beds or even open garages unfortunately.
Fluke units - the features and the variations of model is mind numbing.
What features should I look for in picking a model?
Calibration check | |||||
Meter | 2.0480v Ref. | deviation | 5.0000v Ref. | deviation | |
UNIT61E #1 (22,000 count) | 2.0482 | 0.010% | 4.999 | -0.020% | |
UNIT61E #2 (22,000 count) | 2.0487 | 0.034% | 4.999 | -0.020% | |
ANENG AN870 (20,000 count) | 2.048 | 0.000% | 5.001 | 0.020% |
Snoobler:
Yes Sir, 3.65v up to the 100th decimal is what I am looking for.
I bought a UNI-T that David P suggests,
This unit lists:
DC Voltage - 600V +/-(0.7%+3)
Boondox:
The Fluke 115 lists:
Accuracy 0.5% + 2
What is the +3 vs +2 above?
I am going to wait for a deal on the Fluke 115, I could not find a deal right now.
Also, I want to put a volt meter/gauge on the battery with a switch to display the volts. I could not find an accurate waterproof volt meter with a LCD display, bright is good too as it is going to outside on the boat.
The Fluke 1xx units aren't officially sold in the US. They're great units, but be aware that they're graymarket here. (I've verbally abused Fluke over this, I think it's the dumbest decision in business.)
I can recommend the Aneng AN8008 or any of its derivatives. But never trust a meter -- hit up VoltageStandard.com or DMMCheckPlus.com and get yourself a calibrated reference, they're super cheap. Store it somewhere, and check ALL your meters against it once in a while.
I bought one off ebay, voltagestandard is the cat's ...man, if you were close by we could swing byI'm in the process of buying the cheapie reference unit from voltagestandard.com. Better to know your meter is off, than to assume it's right.
This meter is upgraded to E+.For low cost the Uni-T 61E gives 22,000 count (more decimal points) and 0.05% accuracy. They are about $60.
For LFP cells, if you want to estimate state of charge from open circuit cell voltage you need better then 5 mV accuracy. That requires meter in 0.1% accuracy range. Many of the cheap DVM's do not meet their claimed accuracy spec. I have checked six of Uni-T 61E bought over several years span and all were better then their spec.
Only negative is they are not super resistant to ESD static discharge damage.