iffn âMy guess is something in the protection circuitry failed.â then it probably wouldnât show any voltage?
Maybe the shrink-wrap is protruding and keeping the negative bottom from contacting the charger contact?
One of the four I got from 18650Canada did that. I eventually found a charger that wouldnât reject it. It was very slow charging at first and then got better. It took a full charge and never got hot. After the first charge its been good. My Miboxer C4-12 charges it properly now and of the four batteries it has the most capacity and lowest internal resistance.
Now it didnt register as charging in any of the slots, but the voltage did rise to 3,8V. I did decide to experiment with the cell. I stuck a 50ohm resistor across it and the voltagr immediately dropped to around 2,9V. As soon as i removed the resistor it went back up to 3,8V. I decided to put a 15ohm resistor across it and the voltage dropped to 0,0012V. After I removed the resistor it went back up. I think this has something to do with the overcurrent protection circuitry. The remaining 3 cells from the same order do not display this behaviour. Its preventing it from both charging and discharging.
Here is a detailed look at the protection circuit board on those SAMSUNG INR18650-35E sold by banggood. After I removed it the cell started charging again. I will keep a close eye on it and do some discharge tests on it later. I do not see any obvious signs of failure or damage on the board.
From now on, I will not buy protected cells unless the device specifically needs them. I did not now these are sold unprotected and banggood/their supplier just adds these onto the cells. I am think of removing the protection circuit board from all of them.
Was there a wire along the side from the positive terminal to the board? How did it get voltage to supply the DW01? For example this is how they typically are used,
Yes, there was a wire (more like a metal foil) running from the positive to the circuit board. You can see it very well on the third photo of the battery on banggood site.
Sometimes the DW01 doesnât start up and needs to be reset. This is the âshipping conditionâ so that the cells are not hot during transport. See the note in red on page 8 of this datasheet.
i have seen this circuit lock up before also but never figured out the cause. It seems as if there is a latching circuit of some sort and it requires current to flow thru the bypass diode to reset it.
âshipping modeâ, to minimize discharge until the product is plugged in for the first time
The battery did fully charge and discharge once. But it sounds plausible that it âbrickedâ and needed reset. Well, its too late to try it now, I tore off the circuit board.
I used to think âHey, it canât hurt, so why not get protected cells?â but quickly rid myself of that idea. Now all I get are unprotected cells, and flattops unless something needs a buttontop.
Even devices that donât have LVP, you still donât âneedâ protected cells. You can tell when the beasties start getting dim, and then you charge them. Only in case where it gets accidentally turned on when otherwise unattended (in a bag, etc.), well, you should still lock âem out to prevent that. At least I do.
Oh, I did it, the cell works fine, I didnt need to rewrap cause the original pink wrap was underbthe clear one they added eith protection circuit, so I deupgraded it to original 35E
Got my 35E and itâs one big mama! My C8+ tailcap stops just before the O-ring but it fits Manker my BLF A6 lol. Iâm thinking about doing the unwrap too but I might just leave it alone.
Well, for low current applications its ok with the protection board. They dont tend to fail very often. But if you need higher current I would circumcise the battery. You know, snip the tip off. But you might loose the buttontop in the process, so be careful.