The balance board does not balance the cells, but that is no problem because charging and balancing the battery pack after taking it off the wall took only 4 minutes and 2 seconds
(The cells were charged and balanced before capacity test.)
If there would have been a large difference between the two cells, the charge/balancing time would have taken much longer than 4 minutes.
These cells are much better than the Original lead-acid battery that became useless after about one year.
A new 6V/4A lead acid battery is also more expensive than these cells + the protection board.
The LiFePo4 cells are still like new, it looks like they will last many years in that solar powered light.
I like the tests of new cells, but i am also interested in re-tests after they have been used in “real life conditions”.
I know it is very difficult to do that, but in this case i will continue testing these cells once a year
In my experience balance boards are designed to start resistor draining the cells at some overvoltage (overcharge) point. This, in my opinion, is a simple but effectively useless approach as overvoltage hastens cell damage (you want your cells to live long, not to die soon).
To keep cells in balance manually I would install voltmeters and pushbutton enabled bleeding resistors at each battery stage.
I've seen such top before (BAK 18650-34T), take a look right here. Not a bad cell, but I prefer not feeding bad business models. You can buy BAK 34T cells with a lot less misleading wrapper. For example:
Hello HKJ, I suggest you the test of a new cell in format 18500 that I discovered recently and which offers better capacities than those proposed by Sanyo, Panasonic or even more recently the rewrapper “Vapcell”. It is a cell manufactured by YLE (YikLikEnergy) in the format 18500 with a nominal capacity of 2250mAh (and it is not exaggerated!) For a continuous maximum discharge announced at 4 Amps, to see if in reality we can not push to 5A see more … They are sold in pairs what will arrange you I think for a test, here is the link to buy a pair (box provided):
Personally, i have tested the YLE 18500 2250mAh, their announced capacities are reals but according to the returns I had on “YCDC 18500 2500mAh” they would be 18500 2000mAh with the exaggerated capacity, incidentally there is no official datasheet for “YCDC” while the ” YLE 18500 2250mAh “have an official datasheet as you can see in my post. And yet I’m not a big fan of Chinese manufacturing cells, but this one from YLE are really excellent I must admit, even Panasonic does not do as well.
Mmmkay but, who is YCDC? These plain orange wraps are far from what any serious OEM would use, and what I was trying to imply is that the “YCDC” cells are probably being manufactured by the same OEM, Changde YikLik Energy, but later rewrapped by a 3rd party who buys cells in bulk from them; maybe lesser grade cells. The cell top is the same, 5 lobes/legs and same shape I'd say.
It is great to have advancements in other cell formats, but given the above price… :facepalm:
I have such an electronic load. She is a very good assistant for various purposes. Unfortunately, its power is limited to the level of 150W, but it is advisable not to exceed the power of 140W, so if you check prefabricated batteries with a high voltage (for example, 14S = 58.8v), then the current must be selected no more than 2 amperes. I checked the battery for the electric bike and made a mistake by setting the current to 3A, after which it failed and I had to repair it (the output transistor, Schottky diode burned out and also on the circuit board there was a break in the current path).
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
… 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.
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.
