Review request for HKJ [Rechargeable Batteries]

The cell is too long for my standard test rig.

Your tests are more like not only a test, but the destruction of elements under currents of various levels. Why do elements on your tests need holders if the vast majority of elements after such checks are then not suitable for sale or normal use? Your tasks are of a completely different nature and purpose. You create invaluable experiments that open up opportunities for all of us to evaluate the behavior of various participants in your tests with their strength tests. Your visual graphic pictures help us a lot to understand and evaluate the behavior of batteries at a wide variety of loads, after which it becomes clear how they can be loaded and how best to not do it. Those batteries that you test, after your tests, can be thrown into the trash, because under your professional guidance they have already completed their main combat mission. With your help, we get evidence about all the possibilities of a particular battery model in order to select the most appropriate elements for certain consumers as competently as possible.
From all of the above, it is easy to guess why for batteries 26800-26950 you absolutely do not need large holders. Using a conventional soldering iron, you can simply solder the AWG wires to their contacts, which can then be connected to your loads for control measurements. It is only necessary to solder without any expensive (home-made or branded) and very rare type of holders. Why are these holders needed, if it is necessary to carry out testing up to the complete destruction of the elements, which can then be simply thrown away, before that only by removing the control AWG wires from them? In addition, holders can negatively add transient resistances that increase at high currents, especially after a load current level of 5-10 amperes, which is not desirable for any of us.

In short, we all look forward to checking out the new 26800 format

pietropetris answered a couple questions concerning an NCR18650B wrapped cell here and there, Henrik got a couple cells for review, and later I found another green wrapped cell with the same top. I have to ask because the review of these cells is nowhere to be seen.

Thanks.

the destruction of elements under currents of various levels. Not really, Henrik could go even further but his battery holder would either not finish due to temperature cut-off at ≈75 °C, or it would ;-) melt. I usually find reading your posts quite funny volchyonok, looks to be the translation engine. Did you try DeepL translator?

I am experienced in low temperature soldering of cells, did neat looking drill battery pack restorations with complete success adding some serious current paths. I use Bi50Pb32Sn18, with a claimed melting point of 93 - 96 °C, this means it can serve as cell protection fuse in case of serious overheating. I myself could prepare a few “review elements” with separate side by side current and voltage probing paths, we could see testing at least at twice (or :-D thrice) the current 30A limit this way, although sending them to Henrik wouldn't be very cheap.

P.S.: A 26800 cell was reviewed by ThunderheartReviews, see Queen Battery QB26800 6800mAh 20A - the big guy!

I do usually not destroy cells in my testing, most cells can easily survive that I go a little above rated current, but that is not really the reason for my holders. The reason I use these holders is to get 4-terminal connection to the batteries, this improve the result at higher currents.

The fact of the matter is that we do not need third-party tests, but familiar tables from the HKJ master, by which we can compare some elements with others. And what you show on the links (from a Russian guy with a terrible English accent ThunderheartReviews), I already saw a year and a half ago.
In addition, a test is carried out there with a current of up to 20 amperes, and we need to the maximum possible for HKJ 30A, as well as 40-50 amperes, even if the report on such loads will be outside the main table after the test. Elements at the end of the last test with the highest possible loads should be destroyed and suitable only for disposal in the scrap. This is the only way to truly explore the possibilities of these 26800 or any other powerful element. Therefore, the HKJ master absolutely does not need any holders with their contacts, which only interfere with tests with their transition resistance.

Wow, these look really good.

You can also solder four wires (two wires to each pole for plus and minus). It makes no difference to connect or solder the same number of wires. However, for 26800 it is still better to solder, because they will still be used only in large battery assemblies, for which there are only holders in which they are connected using electric welding or a powerful soldering iron with tin

The holders means I get as close to the battery voltage as possible, even welding strips on would not be better, but might be as good.

I can go up to 120A test current if I did the test manually, but it would require a couple of strips welded to each end of the battery.

Soldering is a bad idea, especially for my testing. I do not want any damage to the CID, the battery must be able to vent.

For the 26800 elements, 30 amperes is enough, and for an additional report in the details of the test, also mention the behavior of the graph of the characteristic of the element at load currents of 40-50A. Although, even 30A will be enough for a normal assessment of these 26800, because you still should not count on their long viability when working on currents even 10A (judging by the available graphs from another tester, for QB26800 the optimal discharge current is a maximum of up to 7 amperes). Everything above these 10A can be considered stress loads, completely unsuitable for their long life.

I did not quite understand what kind of ventilation you are talking about.

1) If we are talking about the possible overheating of the elements when soldering with a soldering iron due to the high temperature, then a high soldering speed and a minimum exposure time of the soldering iron to the poles of the element are required. To do this, at the very beginning it is really necessary to clean the diamond file, having diamond spraying, plus and minus contacts, apply soldering acid and with quick movements of a powerful soldering iron (100-200W) apply tin on the surface of the contacts. Only then should you attach two bare leads from the AWG wires and solder them also quickly. After that, you need to take air into the lungs and just blow into the place of adhesions. It will turn out without overheating. During the tests, the batteries also heat up with high currents, while their internal temperature is much higher.

2) If we are talking about additional air cooling during the test with an air blowing fan aimed at a highly loaded cell, this is not entirely true, because the 26800 cells are designed to assemble large batteries that will be carefully packed in protective films and shirts and at the same time in the real place of their subsequent work they will not see any fans for forced cooling. Then what is the point of such additional ventilation, if the test tests need to be brought closer to the real life of operation, and not only to theoretical?

volchyonok, try DeepL translator sometime, please.

I think HKJ does not want to mess with soldering batteries right now, i.e. he's not interested in soldering batteries. He also said “I do not want any damage to the CID, the battery must be able to vent” because heating the battery anode/plus pole may noticeably increase the chances of damaging the CID. CID is an abbreviature which means Current Interrupt Device:

Related article: Battery Safety 101: Anatomy - PTC vs PCB vs CID @ Battery Bro

P.S: I heartily recommend using a low temperature solder for batteries.

Wed, 12/04/2019 - 11:34

All right, then we’ll all stay in the same place in an endless wait.
It’s not clear how the positive terminal can be damaged if the soldered wires are to be soldered to the uppermost contact, which is located quite far from the dangerous area of the safety valve of the element, and you need to do it very quickly, having prepared in advance for normal soldering? In order for the process to take place in a matter of seconds, you still need to have a powerful 100-150W soldering iron with a copper stinger, a short touch of which will be enough not to heat the entire complex unit. I don’t know, but all over the world even ordinary people do it, i.e. not only masters of their craft.

Self-quoting me back from #748…

I think this was overlooked, so I am asking again. Did those cells arrive home and got tested?

Is it this cell: Test of GTF NCR18650B 3400mAh (Green)

Thanks. What a mess. I see one cell gave ≈3135 mAh at 0.5 A, while the other ≈3321 mAh at the same rate (3228 mAh average at 0.5 A). The shape of the curves matches closely. Do you think this is attributable to cells from different production batches, i.e. an old cell mixed with a new one, or more likely different cell model numbers?

I will not guess about that.

This is due to the fact that elements with a GTF sticker have nothing to do with genuine Panasonic NCR18650B elements. If you carefully look at the positive exit, you will receive evidence of this fact:

Panasonic NCR18650B

GTF18650B

We already know, volchyonok. Those “GTF” cells actually are manufactured by a chinese OEM (BAK, as far as I know), bought in bulk by someone, rewrapped with a fake wrap and then sold. Pretty common in china.

I recently ordered some cheap Colaier G35 cells, their top pole says it all:

An EBD-M05 battery tester is also on the way home, I will publish some discharge curves once I get them.

Apollo Max graphene power bank

https://www.indiegogo.com/projects/apollo-max-the-power-bank-recharges-in-19-mins