Found a Quality Battery Resistance Tester

I recently recharged some of my eneloops from 1.24V to their cutoff voltage (1.55V) in my MiBoxer C4-12. According to the charger only 100-150mAh went into those cells. Recharging only took about 5-10min as voltage rose up instantaneously. Their iR was about 60mOhm. I assume these cells can be considered as worn out, right?

Sorry d_t_a,

I don’t know the device.
You should mail the manufacturer. He should know :slight_smile:

Joe

I got some Protected NCR18650B's from Banggood today and they are all reading 60IR on my SM8124A tester. My other Protected NCR18650B's are all reading 48IR on my tester. Would the difference be because they are probably two different protection circuits and therefore showing different resistance numbers?

I'm assuming Banggood is using some cheapo no name circuit whereas my other NCR's are using genuine Seiko circuits.

Yep.

They are probably higher resistance FET on the Banggood cells.

Thanks! Any negatives you know of from the BG cells other than more resistance?

Hmmm no.

I actually have no protected cell, except for the one from my Imalent HR20.

I'm waiting nearly two months for my 30Q's from BG. They will be my first set of unprotected batteries.

Oh.

The customs must have seized your package.

They seize 4x18650s worth 25$CA, but not a phone with a pouch cell, much more dangerous, worth 250$CA.

Mine arrived yesterday. I didn't get a chance to use it, but it looks like the good model. It came in a plain white box with a decent pouch (maybe a holster, didn't look on back for belt loop). I got it from here.

That’s exactly where I ordered, too. So, I‘m confident to get the new version, too. Unfortunately, the shipping address in my Aliexpress order is missing the country even though it was correctly assigned in my account. Maybe just an displaying error.

I finally got 4 x 30Q button tops from Bangood today after waiting for over two months. They all test at 12.0 IR with the SM8124A tester so they are real samsungs!

Mine finally arrived today.

It’s the newer 4 prong model.

Someone said the measurements you get with this meter are not the same you get with your Battery Charger / Testers.

Yeah, I found that to be very true.

How would you convert between the two in order to determine if your charger/tester gives readings consistent with the SM8124A?

They measure differently so there probably is not a reliable conversion method. The SM8124A should give results close to the battery data sheets which use the same method as this meter to determine resistance which is a good start to see if you got originals or fakes. What I have found so far is that if I add 60% to SM8124A readings of protected cells, they match up with the battery charger IR readings. So far, different types of protected cells from different companies still seem to be 60% more or close enough across the board but for unprotected cells like the Samsung 30Qs, the difference was 200% higher with the battery charger than this tester.

Good stuff there. Thanks!

Did you build a rig for this purpose?
Any pics?

I did build something like this before, but I used bypassed spring holders instead of brass buttons. That was very hard to do though, unlike the more refined method I presented to you guys.

However, now that I have made my Beryllium copper springs, I am going to do one that is much simpler to do for everybody, and is much easier to set up.

Awesome. I’d like to make one. But since you know what you’re doing I’ll wait to see how you did it.

When you decide to use your new springs to build your new tester, it won't test IR the same as the SM8124A will it, but instead the second method you mentioned above to give real IR readings?

I have doubts about this device.
I need to do some tests using the DC Calculation method to verify but I’m getting results that aren’t consistent.

That said, I removed the cable separator because the leads were too short to get to both sides of my batteries.
Does anyone know if there is some magic in that simple plastic separator that could affect the readings?

Today, I tested some new cells with my SM8124A. This is the impedance I measured:

Format Name Impedance (mΩ)
21700 Samsung 30T 6.0
21700 Samsung 40T 7.4
21700 Samsung 50E 22.0
21700 Sofirn 4.000mAh 13.6
20700 Acebeam 4.250mAh 21.6
18650 Sony VTC6 11.8
18650 Samsung 25R 12.2
18650 Samsung 30Q 12.5
18650 Imalent MRB186-P30 19.3
18650 Wuben 2.600mAh 23.4
18650 Sofirn 2.600mAh 41.9
18650 Sofirn 3.000mAh 45.2
18650 Xanes 2.600mAh 45.3