Samsung 18650 35E problems (doesnt charge)

Dr.Phillip · 2019-10-28T22:25:39.000Z

Hello guys, I have a problem with one of my Samsung batteries. I have been using my BLF Q8 quite a lot lately during my night walks with dog (with 4Pcs Samsung INR18650-30Q 3000mAh). I charge it every few days and it works for me but I decided to order some SAMSUNG INR18650-35E from banggood and try it with them. I knew that it will turbo to slightly smaller current but I didnt care that much and was mainly interrested in battery life. I tried charging them today (after first full discharge in my Q8) and noticed that one of the batteries doesnt register by my charger and doesnt charge (XTAR VC4 also from banggood). I thought that there might be problem with contacts so I tried different slots, still nothing. I was sure that the cell is dead, but when I measured voltage with multimeter it showed 3,18V. I tried putting it into Q8 alone, it blinked once and the voltage cut off and acted dead. My guess is something in the protection circuitry failed. The other 3 cells work and charge OK. Did any one of you ever encounter this defect/behaviour in 18650 cells?

Henk4U2 · 2019-10-28T22:30:50.000Z

One very obvious remark about protection. Did you remove the (very) thin plastic disk at the bottom?

Yokiamy · 2019-10-28T22:33:33.000Z

The 35E isn’t protected isn’t it?

Dr.Phillip · 2019-10-28T22:38:47.000Z

Henk4U2:

One very obvious remark about protection. Did you remove the (very) thin plastic disk at the bottom?

What plastic disk? You mean on the negative side? There was no plastic disc.

Dr.Phillip · 2019-10-28T23:19:33.000Z

Banggood calls them protected button top. I thought that it meant they have protection circuitry.

Bearbreeder · 2019-10-29T00:09:48.000Z

Look carefully at the negative terminal there may be an ultrathin circular plastic tape on it

If there isnt contact banggood for a partial refund

You may need to video tape the issue for em

deleted-200707 · 2019-10-29T00:15:08.000Z

iffn “My guess is something in the protection circuitry failed.” then it probably wouldn’t show any voltage?
Maybe the shrink-wrap is protruding and keeping the negative bottom from contacting the charger contact?

WTF · 2019-10-29T01:09:46.000Z

One of the four I got from 18650Canada did that. I eventually found a charger that wouldn’t 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.

Dr.Phillip · 2019-10-29T01:19:08.000Z

chinooker:

iffn “My guess is something in the protection circuitry failed.” then it probably wouldn’t show any voltage?
Maybe the shrink-wrap is protruding and keeping the negative bottom from contacting the charger contact?

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.

Dr.Phillip · 2019-10-29T11:56:27.000Z

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.

Yokiamy · 2019-10-29T12:07:56.000Z

I like living on the edge, i don’t use protected cells

Dr.Phillip · 2019-10-29T12:12:12.000Z

Yokiamy:

I like living on the edge, i don’t use protected cells

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.

Yokiamy · 2019-10-29T12:24:56.000Z

No problem, just be careful that you don’t damage the cells.

Some lights need button tops, for my SP36 i just added a blob of solder on the top of a new set of 30Q’s

Dr.Phillip · 2019-10-29T12:38:28.000Z

These are button top, the tops are I think also spot welded by banggood/supplier. The protection circuit was on the negative pole of the battery.

kennybobby · 2019-10-29T13:21:09.000Z

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,

Dr.Phillip · 2019-10-29T13:31:09.000Z

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.

https://banggood.app.link/NttOnz5jb1

There is a clear shrink wrap on the entire battery.

kennybobby · 2019-10-30T00:24:23.000Z

Sometimes the DW01 doesn’t start up and needs to be reset. This is the “shipping condition” so that the cells are not hot during transport. See the note in red on page 8 of this datasheet.

DW01 datasheet

8205A FET 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.

“shipping mode”, to minimize discharge until the product is plugged in for the first time

Dr.Phillip · 2019-10-29T13:50:20.000Z

kennybobby:

Sometimes the DW01 doesn’t start up and needs to be reset. This is the “shipping condition” so that the cells are not hot during transport. See the note in red on page 8 of this datasheet.

DW01 datasheet

The battery did fully charge and discharge once. But it sounds plausible that it “bricked” and needed reset. Well, its too late to try it now, I tore off the circuit board.

Lightbringer · 2019-10-29T15:16:38.000Z

Got nothing to lose at this point. Carefully cut off the wrapper, remove the protection board and sense-wire, rewrap.

Being that it’s apparently still holding voltage, the cell’s probably still good (but discharged), so just use it in a light that has LVP.

Lightbringer · 2019-10-29T15:21:19.000Z

Dr.Phillip:

Yokiamy:

I like living on the edge, i don’t use protected cells

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.

I used to think “Hey, it can’t hurt, so why not get protected cells?” but quickly rid myself of that idea. Now all I get are unprotected cells, and flattops unless something needs a buttontop.

Even devices that don’t have LVP, you still don’t “need” 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 ’em out to prevent that. At least I do.