| Electronics > Beginners |
| How do i calibrate my multimeters! |
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| tggzzz:
--- Quote from: XMA on August 15, 2018, 08:44:19 am ---hello, sry for not reply back to all of you but, can I use the voltage out a 5v regulator as a voltage reference and adjust from there? --- End quote --- Of course you can - but you would be wise to know what voltage that regulator is putting out! And to know that you will either have to know the specified limits (including over temperature and load and time) or measure it. Some regulators are intended to supply an accurate (within limits) voltage with very little current, others are intended to supply current while keeping the voltage within a broad limit. --- Quote ---i am not going for a %9999999999999999999.99999 accuracy? and I need to have these meters accurate because I measure li-ion cells with them and such. --- End quote --- You need to understand and define what is important in your measurements, and then you can specify the accuracy you require. We can't guess that for you[1] Sometimes absolute accuracy is less important than stability and repeatability. A company I once worked for made a very expensive test set with an accuracy of 0.1dB and a stability of 0.001dB. The customer didn't care about the 0.1dB, since they were interested in changes over 1 week. [1] From https://entertaininghacks.wordpress.com/library-2/good-questions-pique-our-interest-and-dont-waste-our-time-2/ Tell us your problem/goal, as well your solution. In most walks of life, technical or non-technical, if we know the reason for the question you will probably get a better answer. Either the answer will be more pertinent to your needs, or perhaps it can suggest a better alternative that you haven’t even considered. Don’t ask “Can you give me a lift into town?” Do ask “Can you give me a lift into town, so I can replace my broken frobnitz?”. The answer might be “There’s a spare frobnitz in the attic”, thus saving time, money, the environment – as well as making some space in the attic. |
| CatalinaWOW:
For measuring Li ion battery's you need 4 1/2 digit precision, and want 4 1/2 digit accuracy. But you can get by without the accuracy. By observing readings on fresh new batteries you can learn the correct behavior as measured by your meters. The other thing you need is stability so the knowledge you gain is useful over time. Having two meters is helpful because they are unlikely to drift the same way. Differences between them that change over time are a warning to re-examine things. |
| Old Printer:
For hobby purposes measuring LiPos is not all that critical. 1/10th of a volt plus or minus is close enough to prevent over charging or over depletion. That is a lot for even a $5 Harbor Freight meter to be off. Rather than using a voltage source that is not designed for calibration, you would be better off finding someone with a little better meter than you have to compare readings. Pretty much any $20 multimeter that is new will be far more than accurate enough for monitoring LiPo use. My local Craigslist is loaded with people selling brand new DMM's for cheap that they were given and don't know how to use. |
| CatalinaWOW:
A tenth of a volt is marginally good enough to prevent overcharging/depletion. Not good enough to evaluate balance. |
| Old Printer:
--- Quote from: CatalinaWOW on August 15, 2018, 02:42:28 pm ---A tenth of a volt is marginally good enough to prevent overcharging/depletion. Not good enough to evaluate balance. --- End quote --- OP has not said anything about balancing, actually he hasn't said much about why he need to do any of this, but yes you are right. Balance can be done with a fairly inexpensive automatic charger/dis-charger. I have a couple for my quads. They are cheap and very accurate and leave you free for the simple things like manning a fire extinguisher :) |
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