Review: UNI-T UT61E digital multimeter

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HKJ
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lagman wrote:
I was just thinking: Maybe that the meter wants to see AC current (going one way then the other). In my application I have no current or 2A, but never a negative current. Could that be the reason why it's not working?

It is not supposed to be that, because the DMM shows DC range.

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lagman
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If you have enough time could you please try to measure the strobe frequency with your UT-61E? Just to check if it’s working on yours.
That would be very kind. Smile

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lagman
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I’ve also posted the same question on EEVBlog as I’m sure there are many people who could know the answer there.

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HKJ
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Now I got time to test it. You where correct, the problem is that it requires AC. Pulsing current is not enough, it must go negative, before the frequency and duty cycle will work.

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Thank you HKJ for testing this as I don’t have the equipment to do this (easily).
That’s quite annoying that it requires to go negative.
And it’s strange that it allows to display frequency in DC mode as it can’t do it!

Thanks HKJ, you are the best! Smile

My English isn’t perfect but I’m trying to improve it. If you see something that doesn’t sound right or is just plain wrong, please feel free to point it out! Smile

deathless
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Thanks for the review, it was great! I do like the computer connect feature, but I myself forked out enough $$ for a Fluke 87 and I couldn’t be happier.

pipifax
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Quote:
Discharge Capacity

= 0.5s * 1h/(3600s) * 1000mA/(1A) * I(t)

where I(t) must be measured in the ampere "A"-setting, e.g. 0.201A

Thank you HKJ for the nice review!

 

I am experimenting myself now with logging the current of BT-C3100 charger, quite some fun Smile

To me a more logical approach of estimating the discharged capacity from UT61E log file is by first calculating the mean pseudo-constant current draw for a subset of the logged data and then multiplying this number with the runtime of this data subset.

For example the DMM recorded 3000 data points including preceding and succeeding zeros {0,0,-199,-204,…,-213,-195,-197,0,0,0}miliamps, then the average current draw would have been {0+0-199-204-…-213-195-197+0+0+0}miliamps divided by 3000. The DMM needs 1500 seconds to record the 3000 points, so the runtime is (1500/3600) hours. Putting everything together we get

discharged capacity =

= ( {0+0-199-204-…-213-195-197+0+0+0}mA / 3000 ) × (1500/3600)hr =

= {0+0-199-204-…-213-195-197+0+0+0}mA × (0.5/3600)hr =

= {0+0-199-204-…-213-195-197+0+0+0}mA × 0.00013888889hr =

= {0+0-199-204-…-213-195-197+0+0+0}*0.00013888889 mAh

 

We could also drop the zeros to get a more meaningful mean current:

= ( {0+0-199-204-…-213-195-197+0+0+0}mA / 2995 ) × (1497.5/3600)hr = same result.

 

BT-C3100 is a fun charger and its mAh readings are not too far off that i could care less Cool

The latest version of the UT61E PC software can be downloaded from here:

http://www.uni-trend.com.cn/product/2014_0504_231.html

The last tab leads to this link:

http://www.uni-trend.com.cn/uploads/soft/140619/UT61B.C.D.E-rj.rar (15.1MB BA3E4CDA, 2014-04-15)

HKJ
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pipifax wrote:
To me a more logical approach of estimating the discharged capacity from UT61E log file is by first calculating the mean pseudo-constant current draw for a subset of the logged data and then multiplying this number with the runtime of this data subset.

This can work for NiMH, but with LiIon you do only have a constant charge current during the CC phase. The CV phase has a constant declining current, there summing all mAh (or mAs) charged into the battery works better.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

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