Found a Quality Battery Resistance Tester

BlueSwordM, thanks for the info - just ordered one of these. It is frustrating getting a wide range of IR reading on my LiitoKala and MiBoxer chargers when evaluating Li-ion batteries!

For those who want free shipping from China, you may check this out:

https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20180627235349&SearchText=SM8124A

Thank you for this find, I will order one as well.

I am also frustrated with IR reading battery chargers (but at least, when I insert a battery, I have a rough measurement of whether I inserted the battery with proper contact, or not - which is good for making charging termination faster for a given current limit).

Btw, you might want to include BlueSwordM’s and tatasal’s links into the original post as an update. I’m usually not the TLDR man, but that would add convenience :wink:

Mine arrived yesterday and I immediately did a series of measurements to compare suspected fake 30Q batteries to baseline 30Qs. Results are posted HERE (comment #283) in the Massive sale on 18650s in the Littokala Aliexpress store! thread.

I have to admit that this Battery-Resistance-Voltmeter-Internal-Impedance-Meter-LCD-Rechargeable-SM8124A exceeded my expectations. The performance I saw exceeded that demonstrated in the YouTube video: Internal resistance test of SM8124A - Is it worth it. The improvement may be due to a difference in probes. My meter also came sans case. Thank you BlueSwordM for providing this tip on a realistic IR meter!

Just ordered one. Should have it in a few weeks from now. Thanks for all the feedback.
After mine arrives I intend to take IR readings of batteries from the SM8124A but unlike other reviews which showed only battery IR readings, I intend to post tables comparing the IR results I get from My MC3000 and IQ338XL vs the SM8124A on the same batteries to show how far off (or how close) the chargers were to the readings from the SM8124A

The MC3000 I have gives IR readings on the same battery that are often way off from the IR readings I get on the AccuPower IQ338XL although both seem to stick to their guns and present fairly consistent readings for those same batteries on subsequent test cycles. An EE could perhaps use the SM8124A to calibrate the chargers by adding or changing resistors as needed.

I realize that every charger could be slightly different in the IR readings it gives but this should provide a baseline or at least the results from one for general purposes.

I tend to believe the readings on the MC3000 more so than the IQ338XL. But this new device should help resolve the mystery.

In any event….new toys are always fun :slight_smile:

A word of note: The SM8124A shown in the video review on YouTube in the link above is obviously different than the one received when ordered on ebay.
The ebay seller does not provide a case and the lead tips are different. What this indicates I do not know. A knock-off maybe?
Or maybe this is the difference between the SM8124 and the SM8124A ??
Some show dual tips on the probes while others show a single, more stout tip.

I'm pretty sure the newer version is the probes with two ends that we got. Also, by looking looking at many sellers, looks like the blue case and box come with the older version and they tried to keep costs down by just sending the unit itself on the newer version.

That helps. Thanks.
Was just wondering why the difference.

@klrman and ActiveAI, thanks for the compliments.

I should get myself a resistance tester, but I already have a 4 wire tester that does the job quite well.

Thanks BlueSwordM for suggesting a SM8124A battery resistance tester. Today mine arrived from AliExpress.

It came with a pouch by the way, although another than displayed in the sellers picture. My 30Q test 7 mOhm and my VTC6 test 6 mOhm. I guess these cells (both from nkon.nl) are real :wink:

Did it come with the new two-prong probes? This seller is displaying pictures of both the old and new SM8124A models together. Thanks!

Can anyone please post a link to the SM8124A we can 100% trust? I mean there are how many sellers on AliExpress….six, seven?…who offer this nice device, sometimes with different brand names, sometimes without the “A”, sometimes with two cables on both probes, sometimes just one cable. I find it hard to decide whom to trust.

I was unfortunately unlucky with some of these Dolidada batteries…claimed to be IMR-55A cells (like Shockli/Keeppower) but they turned out to be of rather poor quality with much less capacity and even less power drain capabilities.

^

Good question. I ordered one from the same ad as slowtechstef.

Thank your klrman, BlueSwordM, tatasal, and others for your contributions to this thread. Been wanting a decent budget IR meter for a good number of years now.

I think it’s worth mentioning that the resistance values from this $50 AC tester should not be compared to other chargers and things that give resistance.

AC resistance measurements are pretty far apart from DC load resistance measurements.

Article:

So while this device is still useful it is not giving you the same measurement you might find in other sources. Also, I don’t think it is as good of an indication of the max discharge a battery can sustain. (like what HKJ or Mooch are giving you)

+1

I forgot to mention. The resistance measurements are at AC 1kHz sine wave. So while accurate, the resistance numbers are often measured to low.

A 4-wire constant current tester is the only way to measure the real DC load resistance measurement.

I read through the article you linked and it was helpful. Thanks. Fortunately, there is a lot you can do with AC resistance measurements, such as:

  1. Measure new cell when you first get them, and then take periodic reading afterward to monitor their health.
  2. Compare measurements against the battery's datasheet to determine if it is in specification. For example, the Samsung 30Q datasheet identifies a typical 1 kHz AC resistance specification of 13.13 ± 2 mΩ. The SM8124A I recently purchased measured my six Orbtronics 30Qs with an average resistance of about 11.5 mΩ (See Table 2.), which is within the datasheet specification. I was shocked that my $50 AC tester was able to provide measurements with this seeming accuracy. Perhaps this is a one-off fluke.
  3. Compare a known battery with one that is suspected of being a fake. For example, if a battery measures considerably more AC resistance than a real 30Q, then it is probably not a 30Q.

Update: I saved this post too quickly and had to make edits. Thanks!

ActiveAl, those numbers are really close to the spec sheet. I would say more than good enough for a $50 tester, especially considering the consistency of the readings which is what I really like about it. My numbers are higher on my cells as they are all protected, but soon my 30Q's will arrive and I can see what numbers they read.

I have the latest model with the two prong cables that BlueSwordM linked in post #3 https://www.ebay.ca/itm/Battery-Resistance-Voltmeter-Internal-Impedance-Meter-LCD-Rechargeable-SM8124A/273104104104?hash=item3f9645eaa8:g:BEIAAOSwWmNapAyf

I also purchased mine from the same ebay seller (i.e., tangzhimin1008) as Kirman (link above). We got the new model with the double-pronged probes and, so far, it is exceeding my expectations in performance. I used it to determine that six 30Qs from the LiitoKala Factory Store were probably fakes. In this endeavor, my SM8124A readings were very consistent and reasonable. See Table 1 and Table 2 in this post for my data. Note that the average reading for the six real 30Qs (Table 2) was within the typical 1 Hz AC specification of 13.13 ± 2 mΩ given in the 30Q data sheet. This blows me away.

The cheapest purchase alternative for a SM6124A appears to be from this Ali Express Store. But there is no confirmation that they are selling the new model. Suspiciously, this store is displaying pictures of both the old and new models.

Did you get the SM8124A with the two prong-probes or the predecessor without the „A“ and single-prong probes?

Has HKJ already put an eye on this fine device?