Very interesting albeit not much variation in IR values.
Thanks again for this work @dmenezes
I’m not sure if the ‘help’ thread is the best place for this info, but it might be of help to someone, so…
EDIT: Keep in mind that both the discharge cutoff voltage value and discharge current / rate used in the referenced cell manufacturer’s capacity ratings is unknown, so direct comparisons of this data with those ratings is not practical.
In the course of doing some cell testing in the past couple of weeks, plus the initial checkout of a new ‘charger/analyzer’, some data I noticed in my notes may be of interest to some, so I’ll share it:
The 2 devices in use were / are:
- Opus BT-C3100 V2.2
- SkyRC MC3000 FW Rev: 1.15
I ran discharge tests on 4 new examples of NItecore NL-166 , protected 16340 cells which have a rated capacity of 650 mAh. Discharge current used was 1.0A, and discharge cutoff voltage was set to 2.8V on the MC3000, and the non-configurable default value of the Opus is the same (~2.8V).
The resulting capacity (in mAh) indicated by the MC3000 was:
Cell #6 - 671
Cell #7 - 677
Cell #8 - 677
Cell #9 - 666
The next day I ran the same test on the Opus, with the following results:
Cell #6 - 718
Cell #7 - 709
Cell #8 - 741
Cell #9 - 725
The next day I re-ran the test using the MC3000, with the following results:
Cell #6 - 673
Cell #7 - 679
Cell #8 - 682
Cell #9 - 669
Those results would seem to indicate that the capacity results of the Opus are, in this particular case, ~7.5% higher than those of the MC3000.
It also indicates that the change in average measured capacity (per the MC3000) between the first and third tests was minimal / negligible (~ +3mAh, or +0.446%).
About a week later, I tested 4 samples of NL-169, a newer version Nitecore protected 16340 cell with a rated capacity of 950 mAH using the MC3000, with same parameters as previous tests. Those results were (in mAH):
Cell #1 - 905
Cell #2 - 913
Cell #3 - 911
Cell #4 - 897
Following that, I re-ran the test on the same 4 cells, but this time I used a discharge current of 0.5 A (rather than 1.0A used on all the previous tests) with these results:
Cell #1 - 925
Cell #2 - 938
Cell #3 - 940
Cell #4 - 924
Although the effect of different discharge rates on measured capacity is easy to determine from looking at any proper manufacturer-provided discharge graph, this just provides a real world data point I happen to have in front of me. This 50% reduction in discharge current appears to have increased measured capacity by ~2.8%.
Just FYI. As you were…
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That’s good data right here! Thanks for posting it!
Going over to SkyRC MC3000 webpage, I notice there is a firmware update v1.18, dated 2023-05-25.
I updated my MC3000 to this firmware (it was previously v1.15, from around 2 or 3 years ago).
There doesn’t seem to be any changelog of notes of what changed. Maybe someone has any information about the firmware update? (my guess is that these may just be some compatibility issue update with respect to the smartphone (Android or IOS) apps)
If you read back thought this thread you will pretty soon have as much info on firmware updates as anyone else has. Namely, that there is no info as SkyRC does not issue changelogs.
Just something I noticed after updating my MC3000 from v1.15 to v1.18:
the DC IR resistance reading becomes too low.
for instance, I had a high-drain 18650 battery that registers around 28-31mOhms back in firmware v1.15
but after updating the v1.18 firmware, the DC IR reading is just 6-7mOhms.
another button-top 14500 battery (button-top will usually have much added resistance),
in firmware v1.15, it was reading around 100-110mOhms
but in firmware v1.18, it was just reading around 20mOhms
since I had previously been jotting down the DC IR values of many of my batteries (using the v1.15 values), I decided to just flash back to the v1.15 firmware, which appeared to restore to the old DC IR values (which I deem is the “more correct” one, compared to the too low DC IR reading with firmware v1.18)
Maybe if someone else can test their MC3000 if the v1.18 firmware also (significantly and probably incorrectly) reduces the DC IR measurement reading (when compared to v1.13-v1.15 firmware)?
My MC3000 came with 1.17 and both 1.17 and 1.18 show unrealistically low IR values.
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I think that people commented on this IR measurement change in 1.17 in the big CPF thread on the MC3000. I think @dmenezes was going to do some comparisons by flashing back and forth between the versions. Maybe that is still in the works. But it appears that @d_t_a has answered this question.
I am on 1.15 on both of my Mc3000s. It would be nice to understand what other changes were made from 1.15 to 1.17 or 1.18.
For now, if nothing else than consistency in my measurements, I think I will stay with 1.15.
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My general professional experience would suggest that sticking w/ Rev. 1.15 is likely the best decision, for the time being, and unless / until there is known, concrete information which indicates the need to do otherwise. If ‘updated’, The chances of incurring a ‘new’ bug are likely just as high as correcting a currently unknown / undefined (to me) defect. If updated, the ‘risk’ is high, and the ‘reward’ is currently not established to exist (to the best of my knowledge), so that wouldn’t appear to be a good decision. My MC3000 shipped with Ver. 1.15, and that’s where it will remain for the foreseeable future.
That aside, here’s an interesting comparison of internal resistance measurements on 4 brand new samples of a 16340 cell using:
- Opus BT-C3100 V2.2
- SkyRC MC3000 FW Rev: 1.15
Most of this info (capacity measurements) was included in my post on the testing on 09/20, however here I have added internal resistance measurements which were / are not included in that original post:
The resulting capacity / internal resistance indicated by the MC3000 was:
Cell #6 - 671 mAh - 0.153 Ω
Cell #7 - 677 mAh - 0.163 Ω
Cell #8 - 677 mAh - 0.137 Ω
Cell #9 - 666 mAh - 0.153 Ω
I then ran the same test on the Opus, with the following results:
Cell #6 - 718 mAh - 0.257 Ω
Cell #7 - 709 mAh - 0.249 Ω
Cell #8 - 741 mAh - 0.226 Ω
Cell #9 - 725 mAh - 0.248 Ω
One thing which may be of interest anecdotally to you is the difference in measurements between those 2 testers.
Equally significant, if not more so to me, is that I have compared the internal resistance measurements for a number of different cells, and compared those results with those published in HKJ’s test results on the ‘lygte’ site. I am satisfied that the internal resistance measurements I’m currently getting w/ my MC3000 are very consistent with those published by HKJ for comparable, and in a few cases, the same types of cells. Therefore, I currently have absolutely no reason to suspect that the internal resistance measurements I’m currently getting using Ver. 1.15 are anything less than ‘accurate’ (within the limits of the tester’s design). I consider his level of expertise to be pretty good based on what I know, and further, he has access to far better test equipment than I currently do. This is the primary specific reason why I have no current intent to update from Ver. 1.15.
I will of course reevaluate this as new data / info may come to light, but for today, you couldn’t pay me to update the firmware on my MC3000.
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Interestingly though…IIRC, SKYRC made the IR resistance change in response to what they thought was a problem with the measurement in earlier versions. I agree though, having compared the IR measurements with 4 wire testers, it is close enough in 1.15.
Let me just put a finer point on what I posted earlier for clarification. If the measurements in a later version than Ver. 1.15 are indeed in the neighborhood of 400% different than those obtained w/ Ver. 1.15 (which from the above posts appears to be the case), based on what I posted earlier about my own observations and comparisons with HKJ’s numbers, it is the newer numbers I would consider suspect, not the numbers I’m seeing w/ Ver. 1.15. Like I said though, if any new concrete, empirical, verified data comes to light which conflicts with that view, I hope it gets posted here, because that would indeed interest me and potentially change my view of the matter. In this case, I value numbers over words.
Speaking of ‘numbers’, just for grins I re-checked HKJ’s test of what were ostensibly the same cells I listed my test results for in my above post; albeit the former is from a number of years ago (unfortunately HKJ doesn’t date his test reports). If you look at his results linked here, while the capacity numbers in his results are much closer to those of my MC3000 than those reported by my Opus, the opposite is true of his internal resistance measurements, which correspond more closely with those of my Opus.
I can say that although HKJ’s internal resistance numbers are generally (just from casual observation) very close to those I see for similar types of cells with my MC3000, that was not really the case in this particular instance.
Suffice it to say this leaves some questions unanswered with full certainty, so I should add a pinch of salt to what I stated earlier, and current empirical data like that posted by @d_t_a and others may be the most definitive. Unfortunately I don’t have the setup to do same-time same-sample testing w/ a proper standalone 4-wire setup, and that’s really what we’d need to nail this down (reference to a known independent standard).
But, isn’t the real question whether the 1.15 firmware shows IR that is closer to actual values than the later 1.17 and 1.18 firmware values?.
I tend to think that none of the chargers with the slider type of contacts give highly accurate and more importantly, repeatable IR results. I can just remove and replace a cell, or hold pressure on the contacts while measuring, and get significantly different measurements. I tend to use the IR measurements from this kind of device as a rough guide, not definitive measurements.
I’ll get back to you when time allows.
I think we’re more ‘talking around each other’ than in fundamental disagreement (with one possible exception).
The objective is singular, and simple: relatively accurate measurement of cell internal resistance.
There are several factors involved in achieving that objective. My comments have not attempted to address all of those several factors. I will expand my comments to address all of the several factors involved in achieving the desired objective. That is beyond the scope of what I intended to address in my comments. I will expand the scope of my comments to include all of those factors, including those which you have raised, but which I did not (attempt to) address. I’ll need to complete one ‘experiment’ to do that, so stand by and I’ll gladly do that. We can then discuss the full scope of all of the several factors involved in achieving the objective.
I noticed in the section “Firmware” here:
https://www.skyrc.com/MC3000_Charger
It seems 1.18 is the latest version (2023-05-25) but is only available for Windows…
How can I update to 1.18 on MacOS Sonoma 14.0 ? There is one MacOS download but its only 1.15 (2020-03-30)
You can’t. You can run Win10 in a VM and install from there, though.
OK thanks, does the mobile app (Android / iOS) have the ability to update firmware?
No
Not sure of the accuracy, but I found the following over on CPF in the MC3000 thread regarding firmware V1.18:
“In a video review they told there is an improvement in bluetooth (I didn’t understand how they can assert this), moreover the bluetooth MAC is now shown in the menu. Instead, no changes about the unrealistic IR low value found in release 1.17.
Then I will stay with 1.15, although I would like to get more information about the changes about bluetooth. Unfortunately at the moment it is quite unreliable.
I find incredible this kind of slovenliness of SkyRC that does not publish any firmware release notes.”
FWIW
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So far I’m still on 1.18, and anecdotally I’ve been seeing values very much in line with what I got from 1.17 (the version the charger came with).
RSN I plan on downgrading to 1.15 and accumulate more data, and then put all the data in a spreadsheet to make some comparisons. But @Desertcat already published very good data right here a couple of posts back, and I don’t think I will find anything very different from that.
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