Hello. Which charger currently has most reliable battery internal resistance measurement, for both Lithium and Nickel cells? (Except hobby chargers and MC3000 please).
Since the author doesn't want mc3k discussion in his thread.. :mecry:
I saw a similar question on the geman forum. The OP couldn't produce
consistent Batt IR measurements with the mc3k and questioned the acquisition. I commented that, unfortunately as so much in serious life, if one wants to produce serious or ambitious measurements (like HKJ) which are suitable for publication or future reference, the mc3k device takes a minimum of personal efforts to produce such measurement results. The key reason for this being the various contributions of
contact resistances per slot (
dtsch. Kontaktwiderstände, Übergangswiderstände, Kontaktübergangswiderstände). Let's count, (+)TERMINAL-(+)BATTERY, (-)TERMINAL-(-)BATTERY, SLIDER-RAIL; that's 3 contributions. If you modded (it is possible but don't ask me how lol) the mc3k to having FourTerminalSensing (actually, it is ThreeTerminalSensing in practice) slots, you would eliminate the SLIDER-RAIL contribution only, and the total contact resistance would still depend on the contact pressure. Contact pressure is highest and optimal in a fixed bay charger like the MH-C9000; the AAA and AA batteries are really firmly seated between the contacts.
What kind of personal efforts? Well, amongst others, a fully serviced, maintained, re-calibrated unit, plus the manual minimization of the total contact resistance. Clearly, the ambitious tester tries to find the minimum of the total contact resistance (in a particular slot), before he proceeds with the test (Batt IR test, capacity test, whateva test) and publishes the test results.
Getting consistent and reliable Batt IR measurements with the mc3k is, due to the personal efforts, a bit challenging at first. Same with sharpening knives, tuning an old violin, or frying perfect eggs sunny side up! We are talking here +1 milliohms(!!) resolution, so any disturbing factors must be taken into account, eliminated or minimized!! Unless the battery is soldered to the PCB, you cannot eliminate contact resistance. So you can only minimize it by maximizing the contact pressure, e.g. as seen in the MH-C9000 or NC2500 fixed battery slots.
Nuff with the blablah. My unit was serviced and re-calibrated over a year ago. So, for my test videos, i only had to look out for the minimal total contact resistance and then try to reproduce the minimum before turning on the camera! The "trying to reproduce" took me an average of ~5min. So the time difference between each of the 4 video clips is ~5min. I didn't feel like video recording the 20mins of efforts (= 4*5min), i am showing the end result only. As any reviewer/tester does. As any pianist does. No pianist video records how he progresses studying a new piano piece until he finally gets to public-worthy performance quality!
The point of the footage is NOT to teach you how (
what i did in the 5mins) to get to each of the four video results. The point of the footage is to prove that
consistent Batt IR measurement
is possible on the mc3k. Note: The test results are also
reliable, as long as you repeat them under the same battery conditions: the battery should be well-conditioned (i.e. not a sleeping battery), fully charged, cooled off, and clean. lol.
Through rotation of the 4-bay configuration each battery was tested in every slot.
WHITE: 94, 94, 94
BLUE: 86, 86, 86
VIOLET: 86, 86, 86
YELLOW: 81, 81, 81
YELLOW: 81, 81, 81
WHITE: 95, 95, 95
BLUE: 86, 86, 86
VIOLET: 88, 88, 88
VIOLET: 86, 86, 87
YELLOW: 81, 81, 81
WHITE: 93, 93, 94
BLUE: 84, 84, 85
BLUE: 87, 87, 87
VIOLET: 87, 87, 87
YELLOW: 81, 81, 82
WHITE: 95, 95, 95
The batteries are from my set of
Eneloop Panasonic Tropical (manuf. 2014), have been re-conditioned just now (BREAK_IN, followed by 6 cycles at -0.5/1.0A with MH-C9000, avg. mh-c9000 capacity reading ~1890mAh) and have been discharged to 0.9V without D.REDUCE prior to the above Batt IR measurement tests. Afaik Batt IR measurements should not be taken with discharged batteries, because this would produce unreliable or unstable results, but .. the heck i thought and did it anyway haha, with no detrimental effect in this clip series, as we could see.
To cut the whole post short:
If i gave my mc3k, this very unit!, and my Eneloops, this very set of 4 well-conditioned samples!, to my RC hobby savvy neighbor and asked him to shoot a
series of videos showing 4-bay configuration rotation and measurement of Batt IR (3 readings per battery per slot) — basically doing exactly the same what i did in
~22mins of efforts! — he would have shot everything in
1 single video of
1min length and gotten completely different measurements showing in his video footage:
whose fault for the discrepancy between mine and his footage would it be then? Is it the device's fault? Or is the mc3k user to blame? I will let the buyer/shopper decide upon this question.
The gist is, it really
does take some efforts (time, energy, efforts, experience, practice, patience, frustration, knowledge, understanding, etc) to get things as beautifully right as seen in HKJ's review or the above set of 4 video clips ... regarding the ambitious measurement of battery internal resistance with the mc3k charger. ( Btw before i start very serious capacity tests, i use the Batt IR function too to learn the total contact resistance minimum per slot. Extra contact resistance, for example caused by my flaking dandruff, would ruin the beauty of the capacity test results. )
.
cycles with this setup for the sake of testing, but i will. Summer is long. So.
in a dream future and asked me about ideas for it. With DEX, you can control which data columns and in which format (how many decimals, which time format, etc) and which sessions and slots are to be included in the exported *.CSV-file. One wouldn't have any such controls if a "mc5k" logged directly to card (unless a raspi were integrated in the mc5k casing - crazy idea). 
