Are 30Q 18650s genuine at ~42/43g? - UPDATE: all customers being refunded

Mine 46.6

I have 2 Samsung 30Q from Vapcell (not rewrap)
45.5 g each

My two year 30Q @45.9g.

@zoulas, as in, the internal impedance listed as 26mOhm (#7.5 in that PDF)?

Can I just use my multimeter to get that?

Here are the weights of all of the cells:

42.8
42.7
42.7
42.9
42.9
42.8
42.6
42.8
42.9
43.1

My Fluke 115 says it can’t get an ohm reading from the cell.

I also have a Tenergy TB6-B charger that I could use to perform some test—but I’m not sure what to try.

I wrote the seller and I’m waiting to hear back.

An update from the seller:

Weigh/test your cells, folks.

On that note, what equipment should I buy to test my cells?

As they do in the legal system, you need to have a preponderance of evidence. So you will have to check several things including weight, IR, dimensions, etc. Its not enough to simply weight it.

How do I check the IR? I tried measuring the resistance with my Fluke 115 and got nothing. What’s the difference between IR and internal impedance?

Thanks. Is internal impedance the same as internal resistance?

For what it is worth, IR changes with temperature, state of charge, number of cycles and discharge rate for the test.

As with a lot of things, getting a number is just half of it. Understanding the parameters of the test and how those parameters affect the result is the other half.

Does internal impedance also change with those same parameters (temp, cycles, etc.)?

They don’t seem like a bad seller …
why won’t you tell us who they are ?

As I understand it…

Resistance is the “resistance” to a steady state amount of current flow

Impedance is “resistance” when current is pulsed or at some frequency or possibly including the “imaginary part” of current flow. (imaginary part in the mathematical sense, ie SQRT[–1] or i )

So, resistance and impedance can be thought of as the same thing but are technically not the same thing.

@pirate joe 22: I didn’t want to give them a bad name before giving them a chance to make good. They are Battery Junction dot com. I’m quite pleased and I wrote them a thank you note.

@prototype3a: thanks. I ordered a tester that says it can measure it.

Well, I did a drain test on one of the light “30Q” batteries that I got.

I drained one of them at 1A until it hit 3V. Here is the result. 1621 mAh (I assume the counter is in mAh). (I’m going to do a second one overnight at 0.5A)

Is my expectation of seeing nearly 3000 mAh off?

Not off, you should get near 3000mah, probably around 2800

I bought two 30Q cells from techaroundyou in Australia recently and they came with these markings:

INR18650-30Q
SAMSUNG SDI
6 KMT

On the can of cell 1:
R30Q
KAUA1
GAHC
CC
B14
W16

On the can of cell 2:
R30Q
KAUA1
GAHC
CC
B06
W23

Vapcell S4 Plus capacity tests:

Samsung 30Q6 18650 Cap Test #1 (2021-04-22)
Weight: 46g
Discharge 500mA
Max cell temp: 38C
Room temp: 16C
Capacity (mAh):
3046, 3083
Internal Resistance (mOhm):
26, 21

Samsung 30Q6 18650 Cap Test #2 (2021-04-23)
Weight: 46g
Discharge 1A
Max cell temp: 52C
Room temp: 17C
Capacity (mAh):
3094, 3124
Internal Resistance (mOhm):
23, 29

Personally, if you buy from a reliable source, you will likely not have to ever do all this leg work to check for authenticity. Generally speaking, if a particular battery is out of stock everywhere and one place seems to have big quantities in stock, this should be a huge red flag. Right now, Lithium Wholesale is very low on virtually every battery, so this should be an indication of the high demand.

I’ve only bought from liionwholesale.com and batteryjunction.com (this was the first time from batteryjunction). Now I’m going back and checking my liionwholesale.com batteries too.

I’m going to get that Vapcell S4 Plus charger you mentioned. You’re saying it can measure IR?

I’ve been using my Tenergy charger to test capacity by draining from “full”/4.20V to 3.00V at 1A.

Is that a pretty standard capacity test?

What’s an appropriate cutoff voltage to use when draining batteries?

My highest 30Q cell (from another order—used but not heavily) was 2400 mAh.

Most of the cells from this order seem to be around the 1600 mAh range.