Review: UNI-T UT61E digital multimeter

69 posts / 0 new
Last post
kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

to whom it may concern, recalibration of the UT61E isnt necessary imho but it is possible. FOI, some users buy a little product called DMMCheck and do the adjustments on their own.

*FMI* i got 4 i/o sh
Dimitrioptimus
Offline
Last seen: 8 years 7 months ago
Joined: 10/05/2011 - 11:06
Posts: 74

@HKJ or anyone to whom it may concern for the RS232 converters issue

Nowdays serial is obsolete,so connecting to Pc is not possible for those who does not has a serial port,but I found some RS232 convetor to USB in Deal Extreme,many consumer reported that some converters are not working,based upon my observation I found that the better converters are those which has FTDI chips and not prolific chips,since I am not that technically sound plz suggest which will work for Unit 61E,I have chosen these in Deal Extreme based on the customer reviews which are as follows.

1>http://dx.com/p/usb-2-0-to-rs232-adapter-0-8-meter-9656
(highly praised by a user)
2>http://dx.com/p/rs232-to-usb-convertor-cable-2537?rt=1&p=2&m=3&r=2&k=1&t...
(Prolific PL2303)

3>http://dx.com/p/usb-2-0-to-rs232-ii-serial-cable-adapter-converter-black...
(FTDI based converters)

4>http://dx.com/p/usb-to-rs232-dongle-with-extension-cable-5859?rt=1&p=2&m...
(Highest Numbers of reviews)

5>http://dx.com/p/bafo-usb-to-rs232-converter-5947?rt=1&p=2&m=3&r=2&k=1&t=...
(Best built Quality)

6>http://dx.com/p/usb-to-rs232-serial-port-adapter-transparent-green-24512
(Cheapest Price)

HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

Where I have had the most problems with the serial converters is the driver (When I last checked all the supplied drivers was for Win XP), especially with Prolific PL2303.

I solved the problem by buying locally from a company that did supply working Win 7 drivers (Sandberg).

I cannot say which one of the adapter is best or works, that would require that I tested them.

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

Rick NJ
Offline
Last seen: 5 years 7 months ago
Joined: 01/16/2013 - 12:46
Posts: 43
Location: NJ, USA
HKJ wrote:

Review of UNI-T UT61E digital multimeter.

The meter can measure from 0.001 mA to 220 mA in two ranges, this range and has a burden voltage of up to 1.1 volt. The actual resistance is a bit funny, most of the time it is 10 ohm, but when the burden voltage reach about 0.8 volt the resistance will drop. Note: The resistance does not change between 22mA range and 220mA range. To get a more useable current meter, I would suggest getting an 0.1 ohm 1% (or 0.1%) resistor and use the 220mV range to measure voltage over that resistor (See Current consumption, using resistor for a example on how to do it). This meter is missing a 2.2A range. The accuracy stays within the specified 0.5% on DC

I have ordered but not yet received my UT61E. I am reading the manual and doing other research prior to having my hands on the real meter.

The current measurement would indeed have a “funny” resistance. Looking at the UT61E’s schematic floating around on the web, it looks like they use shunts with dual diode in parallel depending on the range.

  • With the max (10A) range: 0.01ohms, two zener diodes back-to-back (++) then in parallel.
  • With other ranges, shunts are: 9, 90, and 900 ohms, in series and 9/900 are in parallel with two diodes (one in reverse). The 900-90-9 are in series then series with a 2ohm where. Drops appears to be measured at left of 900 (900+90+9+2) or left of 9 (9+2) depending on setting

Since diodes are not linear devices, the resistance would depend on the voltage and current. So the resistance will not be a fixed value as in a regular resistor alone but a resistance that changes with I and V. I am no electronic expert. I am not sure exactly why the diodes are there. My best guess is the diodes are to limit the voltage drop across the shunt so it can switch to the higher range without having the lower ranges reading a voltage way too high for it. (Any expert out there? Enlighten me if my guess is wrong.)

If the schematic is right (found it on the web somewhere, doesn’t mean it is accurate): For the 10A range with 0.01ohm shunt, the burden voltage should not have much affect. A 10A current would drop a mere 0.1 volt drop. The 1.2% error at 10A would give a +-120mA error, plus 50-count giving total error of +- 170mA. Since the 50-count alone would represent 50mA, measuring anything below 1A would not be very good with a 50mA uncertainty minimum.

Next best is the mA range with 9ohm in parallel with 2 diodes then series with a 2ohms shunt. The diodes+shunt would manifest itself as somewhere below 11ohms – the diode makes the actual resistance current/volt dependent so how much below 11ohms is hard to say. Inserting that into a say direct drive LED with a 50ohm current limiter, the 11 ohms would introduce a 20% increase in current limit resistance – the 50ohms limiting resistor is now a 61ohms limiter. That current measurement will be rather useless.

Using a 0.1ohm shunt and the lowest voltage range for low current (220mv) would in theory give better measurement. The shunt will be able to measure up to 220mV which equates to 2.2amps. The accuracy at that range would be (according to the manual) 0.1% accuracy giving error at +-0.22mV. The five count error makes total error +-0.27mV or 2.7mA.

So, it looks like I need to find some 0.1ohm shunts.

HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

I have also seen the schematic (now).

The diodes protect the unused range, i.e. is 90 and 900 ohms are in series, when using the 90 ohm resister the diodes are used to lead the current around the 900 ohm resistor. That is the reason for the "funny" resistance in ampere and it does not affect precision "only" burden voltage.

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

Rick NJ
Offline
Last seen: 5 years 7 months ago
Joined: 01/16/2013 - 12:46
Posts: 43
Location: NJ, USA

I hate flipping through the manual to look for the %accuracy/specs each time I change the dial on my meter. So, I cut and pasted the UT61E’s spec for all the selections into a single-page layout. Small prints, but I can see all the %accuracy for all the ranges on this little poster on my wall.

Thought other UT61E may find this useful. If you like it, feel free to use it.

- – - – -
I was going to upload the PDF file here, but I see there is no upload option. So here is a link to EEvBlog under UT61-E teardown photos where you can find the PDF file.

Link to all specs on a single page

kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

Rick NJ wrote:
So, I cut and pasted the UT61E's spec for all the selections into a single-page layout.

Great job, thanks for it!!

 

Smile

i can't believe that i paid only 24.50€ for this baby (incl. discount codes, dinopoints, gift cards, afaicr). best flashaholic related purchase ever!!

*FMI* i got 4 i/o sh
kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

HKJ wrote:
This switch will freeze the reading when pressed, generally I do not find this very useful. Some meters has a better implementation where the meter automatic will hold the last reading, without touching a switch, this is a much better hold function.

HKJ, if you keep the HOLD-button pressed, the DMM will go into AUTO HOLD-mode Wink

*FMI* i got 4 i/o sh
HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

kreisler wrote:

HKJ, if you keep the HOLD-button pressed, the DMM will go into AUTO HOLD-mode ;)

 

No, it is a timed hold: It will lock the reading after some time.

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

kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

oh i see, thanks!

but it's almost as good as AUTO HOLD Smile

*FMI* i got 4 i/o sh
HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

kreisler wrote:
but it's almost as good as AUTO HOLD :)

It is not, auto hold only has to be activated once and they you can take any number of measurements.

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

kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

i never saw real AUTO HOLD in extended action.

will watch more youtube vids!!

Smile

*FMI* i got 4 i/o sh
kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

*FMI*

i've been doing extensive charger tests xp4 and whatnot. anyway my ut61e ran down the 9V battery. i use the ut61e that much, it's now the 5th or so new battery in it since i bought it 2.0yrs da ago. the DMM is able to operate with a cell at 5.455V offline resting voltage. after a few seconds of usage, the online voltage of the cell would drop below 4.855V and that's where the ut61e scrambles the LCD display and shuts down. the youtube reviewer tested the low voltage dmm operation in more detail with a constant voltage source. in reality, cell voltage isn't constant, so in practical terms a cell with ~5.5V offline resting voltage is pretty much the lowest you can go, since as soon as you set it online the cell does a huge voltage drop within seconds and the ut61e shuts off.

and fresh brand-new 9V alkaline has 9.6V offline resting voltage.

and true, my battery tester shows RED, dead cell. at 5.455V, the cell *is* dead. no wonder that the ut61e shuts down operation.

so i don't get it why the youtube reviewer examined how low the ut61e can go.

 

silly stuff.

lol

*FMI* i got 4 i/o sh
Chloe
Chloe's picture
Offline
Last seen: 5 years 1 month ago
Joined: 01/30/2013 - 14:14
Posts: 4595
Location: 联合王国

Modify it to run from regulated power supply?

HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

Five batteries in two years is not bad.

I guess that I replaces batteries once a month or more, but then my most used DMM (A Fluke 189) is between 50 and 100 hours runtime each week.

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

kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

today i am trying to manually measure the Eneloop AAA discharge capacity on a new Wink (hehe.. ) nimh charger which does display discharge capacities. the displayed capacities are a bit on the low side —compared to specs and C9000 results (Refresh&Analyze, Break-In)—, that's why i am doing this exercise. the UT61E comes in handy particularly for its stable unfailing logging capability. the serial cable was included in the package but i also bought the original USB cable from DX.

another beautiful point about this particular model is, because of its popularity the device gets continuously improved through invisible internal hardware revisions and users all over the world write their own PC LINK software (for Windows, Python, Linux, ..). I am satisfied with the original old Win software v4.01 on the CD-ROM but for our information, these are alternative programs compatible with UT61E:

The wiki site does not list the best tho:

There is also an entertaining and impressive UNI-Trend 12min company video (English lang, 118MB, slow download, use D/L manager).

So how does the kreisl measure discharge capacity?

Simply by logging the current I(t) over the entire time t with HKJ's measurement method:

photo courtesy HKJ

One ends up with a data column for I(t) and one for t in Excel. Mathematically the discharge capacity is the integral of I(t) over time t, that simple. In a RL experiment this must be approximated by the sum of I(t)×∆t where ∆t=const.=1/f=1/(2.00Hz)=0.5s, because the updating frequency of UT61E is exactly 2Hz.

Quote:
Discharge Capacity

= ∫ I(t) dt

≈ ∑ I(t)×∆t = I(t)*∆t = ∆t * I(t)

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

where I(t) must be measured in the ampere "A"-setting, e.g. 0.201AIn other words, the amps just need to be added and this sum must be multiplied with that factor, e.g.

(0.201+0.200+0.200+0.197+0.199+0.202+…)*0.1388888…*1mAh

That doesn't sound too hard, does it? Wink

The discharge test is still going on, i'll post my result here when i am done with everything stay tuna.

EDIT:

test done. saved as *.XLS-file, opened with Excel, then simple Sum function:

So we get in 3h33min24s:

|Discharge capacity| = 5600.236 * 0.13888888… = 777.81055555… ≈ 777.8 ≈ 778mAh

The same cell (from brand-new 4-pack) discharged from the same starting condition (i.e. charged at 400mA in C9000 and after completion left in charger for 18hrs) gives the C9000 discharge result 795mAh (in 4h24min), which sounds realistic given the "Sanyo mAh-scale" and their "800mAh"-rating. That's a minor discrepancy of 17mAh.

Maybe HKJ's measurement method which certainly increases the resistance between plus and minus poles of the metal contact plates of the charger (contact resistance + battery + tin foil + multimeter with leads + tin foil + contact resistance = 479-880mΩ total, instead of ~48mΩ total) influenced the system and falsified the result. Therefore we're repeating the discharge test twice: without UT61E on the new charger, and with UT61E on the C9000. after these 2 tests we'll know which of the three devices are consistent with each other and which device is a poor product.

EDIT: tests done.

C9000 current measurement test failed, see below post.

the "without UT61E on the new charger"-test was very successful. I got the same low discharge capacity and time for completion was also the same: 3h33min30s, amazing! It means that my discharge capacity measurements on the new charger are valid in the sense that they do NOT influence or falsify the charger's behavior (although it does so on the C9000!). Furthermore, my UT61E measurements are also fairly accurate, after the Sanyo scale.

What's our take home message?

  • C9000 is very accurate with mAh-readings but also very/too sensitive to non-Eneloop or 1yr+ old cells because the "HI6H" resistance threshold is very low whereas all other chargers on the market do not have any such threshold. Trying to read (charge/discharge) current of a C9000 channel on your DMM in series is a practically an insurmountable challenge! Just give it up already Silly
  • On other chargers, discharge capacity (amateur) measurements with an accurate logging meter such as the UT61E is possible, easy, and fairly accurate. If you own a battery analyzer, then it is a very instructive exercise to compare your own capacity measurements (from calculations with UT61E data) with the capacity readings of the battery analyzer.
*FMI* i got 4 i/o sh
kralyevski
kralyevski's picture
Offline
Last seen: 1 year 2 weeks ago
Joined: 02/05/2013 - 08:37
Posts: 342
Location: Macedonia

HKJ wrote:

This is my first DMM review.

If anything is missing please say so and I will see if I can include it.


i’ve been looking at this DMM for some time now but still haven’t bought it…just one question: can you try to press and hold the hold button for a few seconds and see if the hold on display will blink and then in the next 5 or 6 seconds it should function as on some expensive flukes i.e. not just freeze of the reading…EDIT: i still don’t quite understand difference between real hold function and this “semi-hold”

“the easiest way to become a MILLIONAIRE is: first you become a BILLIONAIRE than you start to be flashaholic”

HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

kralyevski wrote:
HKJ wrote:

This is my first DMM review.

If anything is missing please say so and I will see if I can include it.

i've been looking at this DMM for some time now but still haven't bought it...just one question: can you try to press and hold the hold button for a few seconds and see if the hold on display will blink and then in the next 5 or 6 seconds it should function as on some expensive flukes i.e. not just freeze of the reading

It does not include "Touch and hold" as the Fluke meters.

It has "Hold" that freezes the display immediately and it has "Delayed hold" where the display freezes after a few second.

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

kreisler
kreisler's picture
Offline
Last seen: 7 years 8 months ago
Joined: 11/12/2011 - 23:32
Posts: 3992
Location: Deutcheland

kreisler wrote:
Therefore we're repeating the discharge test twice: without UT61E on the new charger, and with UT61E on the C9000. after these 2 tests we'll know which of the three devices are consistent with each other and which device is a poor product.

well the C9000 test failed and that's probably the reason why nobody on the WWW ever did a thorough technical analysis of the Maha: the tin foil (or aluminum foil) method increases the total resistance between the C9000 metal contacts by such an amount that the C9000 returns the infamous "HI6H" error message and stops the program. with the UT61E connected in series to the C9000 neither an Eneloop CHARGE nor DISCHARGE program can be executed. premature ejac ejection yikes!

did anyone on the WWW ever measure the C9000 current as displayed on the LCD? well i tried to measure its current with my UT61E but the C9000 wouldn't let me. that's disappointing and frustrating. and it reveals a clear disadvantage of C9000: it has serious difficulties with handling slightly poor cells (e.g. VARTA ACCUCELL 1.5yrs old) and it can absolutely not handle poor cells (any old NiMH's other than Eneloop), especially not charge them. Discharge should be possible with poor cells but still remains a challenge: premature ejac is typical in such cases, meaning C9000 is not able to evaluate their discharge capacities (nor are other charger-analyzers btw).

I am still doing the "without UT61E on the new charger"-test to get an indication if the inclusion of a DMM in the system influences the (discharge test) results. Hopefully not.

So far i cannot claim that, if C9000 displays "399mA" current, the actual current really is 0.399A, and tbh the 4h24min discharge time for "795mAh" sounds a bit fishy, but the charger returns plausible, consistent, realistic, reproducible, accurate mAh-readings and that's more important than discrepancies between displayed and actual currents. The latter just makes it harder to verify the mAh-measurements.

nobody asked you kreisl to post all this so why you're writing, whom are you talking to?

erh .. haha. never mind Wink

Blushing

*FMI* i got 4 i/o sh
lagman
lagman's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 05/13/2014 - 12:24
Posts: 583
Location: France

Thanks for the review, I got the same DMM and I’m quite happy. Two things:
1) On mine, when I press for a long time the Hold button it enters a mode similar to the one on Flukes and other. Which means that I can apply the probes, then hear a beep and it will hold the voltage it was at when it beeped.
2) Did you succeed to find a USB to RS232 adapter that works with that DMM? I bought one but it never worked… I get a virtual COM port but no data comes out. I haven’t any RS232 device to find if the problem is the DMM or the adapter unfortunately.

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

HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

lagman wrote:
1) On mine, when I press for a long time the Hold button it enters a mode similar to the one on Flukes and other. Which means that I can apply the probes, then hear a beep and it will hold the voltage it was at when it beeped.

No, it is not like Fluke:

On the UT61E you start a time and it will capture one measurement

On Fluke it will capture a measurement each time the voltage is stable, i.e. after activating auto hold once you can do any number of measurements.

 

lagman wrote:
2) Did you succeed to find a USB to RS232 adapter that works with that DMM? I bought one but it never worked... I get a virtual COM port but no data comes out. I haven't any RS232 device to find if the problem is the DMM or the adapter unfortunately.

I do have a some USB RS232 to version COM port adapters, but I do not remember if I have tried them with the UT61E.

 

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

lagman
lagman's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 05/13/2014 - 12:24
Posts: 583
Location: France

Oh ok. I never had a Fluke. Smile

Can you tell me what RS232 to USB works well for you? If you have time could you please test it with UT61E?

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

HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

lagman wrote:
Can you tell me what RS232 to USB works well for you? If you have time could you please test it with UT61E?

I got a few of this model: http://www.sandberg.it/support/USB-to-Serial-Link-9-pin one or two years ago and they have worked fine.

Note: I have not used them for my 24/7 logging, only for shorter tests.

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

lagman
lagman's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 05/13/2014 - 12:24
Posts: 583
Location: France

Thank you very much. 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

pipifax
Offline
Last seen: 3 years 11 months ago
Joined: 01/05/2014 - 05:50
Posts: 310
Location: BLF

lagman wrote:
Can you tell me what RS232 to USB works well for you? If you have time could you please test it with UT61E?

www.dx.com/p/150054

lagman
lagman's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 05/13/2014 - 12:24
Posts: 583
Location: France

Yes but as said in HKJ’s review it’s better to have a Serial adapter as it’ll create a COM port that can be used in an other software.

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

lagman
lagman's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 05/13/2014 - 12:24
Posts: 583
Location: France

One more question:
I just realized that on the A range, pressing the yellow button enables Hz mode. Pressing it again gives the duty cycle.
So I tried to put the probes in serial on my flashlight. I get a current reading but when I switch to Hz or Duty Cycle it doesn’t work.
I’m doing that to get the frequency of the strobe mode and the frequency and Duty Cycle of PWM at low mode.

Am I doing something wrong? I checked the manual and it says max frequency 1khz so it should work.

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

HKJ
HKJ's picture
Offline
Last seen: 4 days 7 hours ago
Joined: 05/24/2011 - 12:23
Posts: 7425
Location: Copenhagen, Denmark

lagman wrote:
Am I doing something wrong? I checked the manual and it says max frequency 1khz so it should work.

It sounds correct enough, some possible problems can be:

  • Current draw to small for frequency measurement.
  • The current draw is not "clean", i.e. the driver uses a buck or boost converter that pulses all the time.

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

lagman
lagman's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 05/13/2014 - 12:24
Posts: 583
Location: France

My LED driver is direct drive. There is just a MOSFET to control PWM for low mode and strobe.

Current is about 2-3A. It should be enough I guess.

Here is a picture (in case I have something wrong…)

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

lagman
lagman's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 05/13/2014 - 12:24
Posts: 583
Location: France

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?

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

Pages