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Author Topic: Battery Impedance Meter SM8124 mini review  (Read 9708 times)

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Offline Kiriakos GR

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Battery Impedance Meter SM8124 mini review
« on: November 29, 2014, 06:07:53 PM »
Battery Impedance Meter SM8124 mini review

For some time I wanted to have a battery impedance meter, unfortunately most such instruments are coming out from companies which tend to offer them at a price extreme.

This SM8124 is a portable version which is circulating in the market also as overpriced for what it is, but it seems that an ebay seller made the difference and currently it does offer it at 34EUR (cleared payment at PayPal).

I thought to get one for my self as gift for Christmas, and also to share my thoughts about it a soon it arrives with my readers.
By having the DE-5000 LCR meter I think that I can compare both meters to its other, by using one method that a Japanese fellow suggests for converting the LCR in to battery impedance meter by using a DC block filter.

The low eBay price does not include the plastic hard case, but I will take care of this detail as soon it comes in about two weeks time. ;)

All available pictures for it are copyrighted and therefore for now I will share only it specifications.

3 1/2 digits 18mm LCD

Voltage Measurement Range: 0~1.999V, 2~19.99V, 20~199.9V
Voltage resolution:
(0~1.999V) 1mV,
(2~19.99V) 10mV,
(20~100V) 100mV

Internal Resistance Measurement Range: 0~199.9mΩ, 200~1,999mΩ, 2~19.99Ω
Internal Resistance Resolution:
(0~199.9mΩ)0.1mΩ,
(200~1,999mΩ)1mΩ
(2~19.99Ω)10mΩ

Datasheet https://www.ittsb.eu/forum/index.php?topic=961.0
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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #1 on: November 30, 2014, 11:36:47 PM »
Hey I just discovered the original manufacturer !   8)

Shenzhen Sanpo Instrument Co., Ltd.
Product page:  http://www.sanpometer.com/eng/product-detail-SM8124.htm

My own meter is now shipped, and with regular speed that is 7 to 15 Days to Greece.
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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #2 on: January 09, 2015, 12:11:47 PM »
I will start presenting my observations about using this specific tool, by saying that every tool despite it price and performance ability, it does work as a teacher which helping you discover a new world.

In my surprise a simple battery testing application about testing Nimh 1.2V cells from Ansmann and Sanyo Eneloop, was enough so to understand that Ansmann white papers about their cells, containing a serious mistake regarding the condition of the cell which the user should perform a battery resistance (Impedance) measurement.

Sanyo - Panasonic gives the information that battery impedance test should be performed when battery is discharged at 1V and that the End-user will evaluate the condition of the cell by comparing the impedance of the specific cell model according to specifications’ sheet.
For example at that condition the HR-4UTGA cell type is expected to measure 40mOhm or less.
And additionally the ANSMANN 2850 digital cell type it is expected to measure 30 or less according to datasheet.

The mistake which ANSMANN did in their papers is their note that the cell should be evaluated only at full charge.


My own measurements’ shown that impedance evaluation when a cell is fully charged is meaningless when performed with low cost tools, which most users will attempt to buy.

For example the use of SM8124 meter which is capable measuring from the first mOhm at it first 20 Ohm range which is suggested for cells up to 2V max, shown as insufficient to do that correctly, because the impedance measurement of eight Nimh cells shown to be in the range of 5 to 10mOhm when the meter it self it straggles to maintain an perfect zero measurement even when it test leads are well in contact to its other.

The SM8124 which I received at 12C indoor temperature is able to measure with it test leads shorted together a 3 mOhm value instead of the expected zero.
This could be due calibration setting in another temperature than my indoor, but even so when you need to evaluate so small impedance values it does seems as a problem.
Naturally you may take your measurements’ and perform manual compensation when you gather all your measurement data over a paper sheet.   


By combining all facts coming from my very first experiences, now I can safely conclude that a measurement when battery is discharged at suggested level makes more sense because the battery will have it max suggested impedance value and also because the meter will perform a safe measurement by measuring a higher value at it own measuring range, such a way of performing a measurement has much less influence regarding the parameter which called as measuring uncertainty.

The practical problem here is that in order to follow the correct advice regarding those conditions for a proper measurement, you do realize that you are missing the proper equipment which will properly discharge its one cell.
         
My very own original planning was to purchase one advanced charger-discharger with 14 channels and with impedance measurement, at a price range of 250EUR and I was ready to move in that direction but a sudden event influenced temporarily my cash flow and that plan and in now paused.

My alternative thought was to purchase this SM8124 instead, and now I am close to believe that this was a wrong decision especially regarding Nimh evaluation at it 2V lowest range.

The second range of SM8124 is up to 20V / 2 Ohm max, and is the suggested one for Li-Po and similar chemistry of battery cells, at that range my shorted leads measurement over it display is 003 mOhm ( 3mOhm) and definably this range seems as more trusted regarding the uncertainty of measurement factor.

The third and last range of SM8124 is up to 100V/ 200mOhm, by shorting the test leads I am getting over the display a measurement of 00.1 mOhm but the meter seems totally unstable about to retain this measurement at its and every time regarding shorted test leads connection, and therefore what I do see here is a extremely poor measuring stability.

In conclusion I will say that SM8124 is a meter which works as designed but definably it can hardly operate as expected due it budget build.
It would made more sense if the manufacturer was offering three separate models which its one should have a single range so to serve with higher stability it purpose.
SM8124 is not worthless but I can not recommend it either for serious work.

SM8124 build quality internally and externally is poor to average, my opinion is that I have here a product using parts worth 10$ max and it retail price is a game that eBay sellers are involved aiming the highest price due no competition at the current time.
Thankfully even my own experiment about getting this SM8124 it was limited to 39.9 USD range, and so it was not that costly either.


Below is a set of pictures of SM8124 and of my tests.
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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #3 on: January 09, 2015, 12:14:26 PM »
More pictures   :)
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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #4 on: January 27, 2015, 08:07:30 PM »
In order to help any one who has buy this meter, I will add few additional thoughts mostly as confirmation about what to expect about measuring specific battery types.

a)  For 9V alkaline battery is impossible to measure internal resistance because the meter has limited resistance range.

b)  9V Nimh yes it is measurable, my fresh (one year old) ANSMANN typ300 270mAh Max-e it did measure at full charge 9V 691mOhm .... datasheet:  less or equal to 800 mOhm

In my testing of fresh AA NiMH I got very confused.
I did discharge the cells under test at 1V by using 200mAh discharge current, the new ANSMANN Powerline 4Pro did the trick here.
But the numbers in my measurements’ from fully charge to complete discharge was remaining as confusing.
The difference in mOhm between the two conditions this looked as very small (four cells testing).

In order to understand more regarding Nimh cells evaluation according to internal resistance, I got two 10 years’ old AA NiMH cells and I did measurements’ to them too.
These cells measured as 38 (cell No1) & 39mOhm (cell No2) as fully discharged and at full charge their resistance become 22 & 33mOhm.

Before I get in to a conclusion I will say that the AA cell which measuring 33mOhm it does trigger those days my charger so this to display the alarm of bad battery = do not recharge ( Fast charge mode).

So my conclusion is that one cell that is totally healthy it has a very low built-in resistance that could be between 19 to 21mOhm the most as fully charged / discharged (AA NIMH).
Gradually the cell buildup a higher permanent internal resistance, this is the one that changes always according to charge level.

To better understand what I am saying just imagine the old fashion and analog battery tester with those three long labels as  Green – Yellow – Red  which are status indications of Good – Medium – Bad.
What datasheets describe by mentioning the mOhm limit is the highest number which above that the battery cell is characterized as bad or that is way out of it specifications.
The battery will need many years of use so to come up at this point when just aging is the only factor involved.
From the other hand there is no warranty that a single cell it can not rapidly degrade due misuse by a damaged charger or because the user will charge the batteries at the max specified limit of recharge cycles which is given by the manufacturer.

Therefore is acceptable to get meaningless measurements from new and undamaged AA NiMH cells, SM8124 meter it can be of some help only if there is evidence of a poor performing battery, and it assistance will be to help you to spot or identify the specific bad cell.
 

Now I am going to say few words (or better examples) regarding Li-ion cells.

In my motorcycle about a year time I did replace the battery by showing some trust to new Li-ion batteries which are sold as 100% compatible replacements of a usual Sealed Lead Acid (SLA) battery.
This is a 12V charging at 14,5V and my measurement was at 22mOhm.
 

Another example is my three Li-ion batteries which I use with my video camera (as one at the time) and is 3.7V 1900mAh (charged 4.2V)

No 1: Genuine Sanyo DB-L50A ( 2009)  4.15V  128mOhm
No 2: Non Genuine compatible ( 2009)   4.05V  260mOhm
No 3: Genuine Sanyo DB-L50A ( 2012)   4.19V 135mOhm
 
With No1 & No3 I can do today just 30 minutes of use, and the No 2 can work for 10 minutes which I have characterized as garbage.
One 100% well standing cell could work for an hour with my camera at taking footage.
Unfortunately today seems impossible to find any DB-L50A datasheet including impedance (internal resistor) data.
The one thought brings the next and therefore if you are not getting branded batteries which they do have complete datasheet you will be lost because you will not have the official comparison point about impedance measurements’. 
In my case I lost the old SANYO division after the takeover of Panasonic.

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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #5 on: September 19, 2015, 06:46:42 PM »
Today I will add and another example from the world of lead acid batteries, and more specifically for the type which this is used in the application of UPS battery-backup systems.

My APC SUA 1000XL this using two 12V 17Ah, when replaced them I did select New Panasonic SLA Battery LC-XD1217PG.
This according to datasheet should have less than 12 mOhm internal resistance, and a life cycle of 10 years.

Yesterday that is 6.5 years in use, my SUA 1000XL did not pass the battery self test, according to SM8124 tester, this measured 30 mOhm at the first battery and 50 mOhm at the second.
While individual battery voltage stays at 12.4 Volt,  them are unable to supply a constant 10A DC that is required by the self-test function.

Every serious SLA Battery vendor this will offer a datasheet for its and every product that he makes.
All that you need to do is search and find it, or simply email this vendor so you to receive a copy. ;)


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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #6 on: November 01, 2015, 04:39:27 PM »
Today I will add and another example from the world of Ni-MH  1.2V

This pair of batteries was originally purchased somewhere in 2003 and them at 2012 they lost their 50% of capacity and two of the four cells them become unusable.
But these specific two they did survived and was serving in less demanding applications as for example my mosquito zapper.  :)

Them today are totally unable to accept charging and their internal resistor this is 38 mOhm.
Even so I am thankful to Sanyo because back then they was making quality parts when today their NIMH cells no matter their model /specifications, them does not last over four years.   
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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #7 on: November 02, 2015, 07:21:22 PM »
I just steal a tip which I found at the user guide of a Japanese battery analyzer..   ;)

Generally, industrial battery is recommended to be replaced when the internal resistance comes up to double of the unused battery.

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Offline Kiriakos GR

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Re: Battery Impedance Meter SM8124 mini review
« Reply #8 on: December 04, 2015, 07:12:21 PM »
Here is another example from the world of motorcycle batteries, the dry ones which activation this is required.
This is a YTZ9L-BS  made in Taiwan, and possibly the best quality VS price choice among other YUASA batteries build all over the world.

I took my internal resistance measurement of this battery near to the end of it activation, this is now charging at 14.40V and charging current  this have drop to 120mA and dropping.
This measured 12 mOhm and I suspect that it will not go lower than that.
 
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Battery Impedance Meter SM8124 VS YR1030 (2017 model)
« Reply #9 on: August 12, 2018, 10:03:33 PM »
SM8124 today this is now EOL ,  measuring accuracy at milliohm range of  +/- 3% +1 Digit among with +/- 1% +1 Digit for voltage, these are now less attractive as marketing point.
SANPO SM8124 this is no more listed at it manufacturer product page and I have the impression that SANPO does not interested to compete in this market any more.

Somewhere in 2017 a new economy battery Impedance Meter YR1030 this circulates in the market.
Digital controls and screen looks appealing,  internal lithium battery this is a bad idea, but precision of 0.7% at milliohm range this is a good sign if this is true. :P

Either way beware of Asian pricing wars, YR1030 lowest price which I found this is at 12$ US

Personally I think that any one owns SM8124 he does not have to think YR1030 as better just because of the better accuracy specification.
When a battery gets bad and this now has double or triple internal resistance, this is now a brick which it must be replaced ( no matter which meter you own).  ;)


YR1030 electrical specifications

Range -  Minimum Resolution - Accuracy ( Accuracy format: ± percentage accuracy + least significant digits.)

20mΩ    0.01mΩ 0.7%+7 (when ZR function is enabled)
200mΩ  0.1mΩ  0.5%+5
2Ω        1mΩ      0.5%+5
20Ω      10mΩ    0.5%+5
200Ω      0.1Ω    0.6%+5

Specifications are valid within 5% - 95% of the measuring range.
Bellow 5% of measuring range the error may be greater than the above accuracy.
 

Voltage measurement accuracy:

2V 0.001V 0.8%+5
20V 0.01V 0.8%+5
28V 0.1V 0.8%+5

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