I have an xtar dragon vp4 with the probes I’ve been using to measure IR of cells. On a new 30q flat top I can get a consistent 13-15 mOhms. This cell will pull 3.3-3.4A from an xpl-hi light with an 8x7135 driver on high.
Recently got an M43 meteor so I bought 4 30q button tops. These are all over the place with IR measurements varying from 30-40 to over 100 mOhms. They aren’t measuring consistently per cell either. I thought it was just the way I was holding the probes but if I go back to the flat top cell I can still get a consistent 13-15 reading. These cells also pull 1-200ma less on the above mentioned light
I’m guessing this is normal, some resistance added is expected for the extra button welded on. The inconsistent measurements make me wonder about the weld quality though. Makes me think I’m loosing some capacity from them and a bit of performance from the light.
I just received 4 30Q button tops yesterday and one is 85ohm, 185, 447 I believe and 999. Took over 8 hours to charge 3 of them. I will be sending an email to Liion Wholesale here shortly as I got better results with some EBL batteries off ebay for 1/3 the price.
In my Miboxer C4-12, flat top 30Q cells read much lower and more consistently than my button top 30Q cells from MTN Electronics. With that said, the C4-12 isn’t super accurate when it comes to IR measurements.
I suppose I should verify IR with an old school method.
Make sure you measure IR on a fully charged cell for consistency of readings from one cell to another.
The super high readings are because of the battery holder terminals, not the batteries or the spot welds.
With your miboxer try this: leave the negative end of the battery flush and raise the positive end so it touches a little different part of those buttons on the holder. You can likely find a sweet spot that will show like 40-60. It will be slightly suspended but if you mess with it you will see the resistance change by a lot. If all else fails get a qtip and alcohol and clean both.
I found a thread about something similar. It was suggested to lightly sand the battery terminals. My batteries were visibly clean and had no issues charging. The voltage measured fine. The button top didn’t feel loose or anything. I used everything from very light to heavy pressure on the probes before. The vp4 probes even have a very rough pointy knurling at the tips to help with contact.
I had nothing to lose before trying to return them so I tried a light sanding with 200G paper. This totally surprised me but it worked, I got consistent 15ish mohm readings.
Taking 8+ hours to charge is something else though unless your using a charger with less then a 500mah rate.
it’s taking that long to charge because the charger adjusts the rate based on the IR. you can override it and often when the cell warms up a little it will go down
A charger which adjusts the charge current based on the 1KHz AC IR (?) reading it makes? Given the variability of rail contact resistances and other reasons that is pretty stupid, sorry to say.
Yes sanding down the contacts can do the trick because an unseen oxide layer or other debris buildup at the battery terminals may or can happen.
Not sure what your years long crusade is for crapping on battery chargers with IR. It’s simply used to make the charge rate idiot proof and automatic.
I also would like to see how you know it’s AC IR when HKJ’s reviews seem to imply a DC pulse. In any case it’s not meant to be spot on accurate so it’s a moot point.
There are $12 battery load testers on Ebay that can do up to 3.5A discharge tests and 4 wire DC IR if anyone wants to test batteries easily.
Noticed the resistance reading in my Miboxer C4-12 changes everytime I insert battery, even when the same battery is removed and reinserted back to back, so I no longer have faith in this charger. I also can’t seem to get the manual amp rating to stick as it reverts back to auto and takes a full day to charge batteries. Looks like I will be returning to Amazon this Tues when the Xtar arrives.
I can get decent and consistent results with flattops, but buttontops? Never the same reading twice.
Plop ’em in the charger, give ’em a coupla spins to “seat” well, take a reading. Don’t touch anything, just take another reading. And another. And another. And another. Take 10 readings, and you’ll get 10 different results alllllll over the place, not even close to each other.
I figured giving ’em a few spins in the cradle would work to do something similar, but it might just need something a bit more abrasing. I’ll have to give that a whirl…
Exactly. I have 4 of the Samsung 30Q flat tops on their way… just opened up one of my Makita power tool batteries to find 10 Sony VTC4 flat tops, all reading 25-30mohm’s on the same C4-12 charger.
