Confused: Need 'Protected' or is Panasonic NCR18650 OK?

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

The 2.8 volt cut-off of the light is too low. By the time your cell draws down to that output, cell damage is likely to occur. You shouldn't rely soley on the charger to terminate charging of LiCo cells at 4.2 volts if charging a LiCo cell. In the interests of safety you should use a protected cell for redundancy. An alternative to the black-label AW cell, which has a protection circuit would be an AW 18650 IMR cell. It uses the safer LiMn chemistry and thus has no protection circuit. Consequently it is slightly shorter in length than most if not all protected cells.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

rich297 said:

The 2.8 volt cut-off of the light is too low. By the time your cell draws down to that output, cell damage is likely to occur.

Click to expand...

A protection build into a cell is likely to be around 2.5 to 2.8 volt.


It is generally a good idea to get batteries with protection, this way you have a double safety and you will also have some safety if you later uses the battery in another light.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

HKJ, looking at your excellent review of popular 18650s, looks like I'm down to AW1600 (the IMRs, but that's pretty low mAh!), AW2200, and *maybe* AW2600. The AW2600 is 67.5mm (that's less than 68--barely) and it's 18.5 in diameter, which is about the same as the Panasonic that Zebralight uses (18.6 max). Also the Tenergy 2600.

Regarding cutoff, I noticed that Panasonic says that they stop the discharge of their non-protected at 2.5V for testing. So I figured that the Zebralight's 2.8V cutoff gave a little leeway.

But I'm seeing a strong recommendation to get protected cells anyway...even at the expense of mAh.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

The Panasonic is a slightly different make up than other cells. The data sheet states "NNP series 2.5V per cell (2.75V per cell in the case of 2 series or more)."
Also, by the time the cell reaches 3V under load it really won't be able to deliver the current and should be very noticable to you.

At WORST, you may experience reduced life cycle of the cell due to over discharge, though I doubt it. The dangers are greater when used with multi-cell lights. And, the shunts that build up inside an overly discharged battery happen at much lower voltages. And over time. So, if you do run the light to the point where it shuts off at 2.8V (under load) and it bounces back up to a resting voltage of probably ~3.0 - 3.2V simply charge it again as soon as reasonably convenient. I would not be concerned for your safety in the least.

At the other end of the spectrum, while charging, as long as reasonable care is taken I see no concerns either. You can charge that Panasonic cell as high as 4.35V and suffer reduced life cycles, or you can choose to charge it to only 4.1V and greatly increase it's life. Most of us are trained 4.2V is the perfect voltage. Is it really? No. There is no such thing.
The danger comes in when a mostly full battery receives a constant trickle charge over a period of time that can cause internal plating and dangerous failure inside the cell.
Use a quality charger, check your voltages coming off the charger to get a feel for it, put the back of your hand on the cells while charging. If you feel any heat, unplug it immediately.

The final thing a protection circuit does is protect the cell from short circuits and high current draws and reverse polarity hookups. Since you won't have the circuit, try and be especially careful of these things. We are all taught not to trust these circuits anyhow, or at least, not to tempt fate.

Sorry if I am going against the norm here.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

I don't use protected cells for single cell lights. All protected have a potential hazard that un-protected cells don't.....a positive strip on the outside of the cell with just a thin strip of insulation between both the negative cell wall and negative body of the light.
I've ran lots of cells to cut off in Zebralights with no apparent cell damage.
G27

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Any unprotected cell will be short enough, they are 65 mm long and maybe 1 mm extra for a button top.

Generally it is no problem to discharge to 2.8 volt, when running at high brightness, only if you are running at low.

I believe that Panasonic are very safe cells, even without protection circuit, but one deep discharge and you have lost the cell!

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Bolster said:

Do I really need protected batteries?

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no, you don't.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

OK, now I'm headed back to unprotected...maybe unprotected Panasonics are the way to go. Use what the manufacturer uses.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

any cell will be ok, even cheap no name cell, they will all work, just some longer, hey Panasonics are very good cells, so are the sanyo, lg. smasung.
i use unprotected cells for years, in lights that have low v cut off, not once i had any problem.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Since it's a headlamp, and will be next to my brain and eyes, I'm trying to approach this issue carefully. I've read the Li-Ion horror stories.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

so did i, funny some of those exploded cells are protected, and 1 was not even rechargable, lol, and other time signs of battery problem were noticed before explosion, yet it was still used.
you got more chance of cheap protected cell blow up, than good quality unprotected.

cells blow up from shorts, and reverse charging, being it 1 cell light it wont reverse charge, shorts are possible, could be light malfunctioning (never seen it happen, or read of it happen), or could be protection circuit itself, it could happen on any protected cell, but cell with no pcb, and metall strips runing on the side, has less chance of it fail.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Found this interesting thread...which makes the point in places that a quality unprotected is safer than a cheap protected.

http://www.candlepowerforums.com/vb/showthread.php?212415-Panasonic-18650

Unfortunately it appears the conversation was terminated, due to nationality being peripherally involved in the discussion.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

This is interesting - someone in another thread says: "If you charge a non protected cell in a Pila charger, expect 6 cycles or less. There also is the possibility of fire."

So if I get Panasonic unprotecteds, I can't charge with a Pila charger?

Can that be true?

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Bolster said:

Can that be true?

Click to expand...

No.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

I have a couple of Pila chargers. I have charged unprotected cells hundreds and hundreds of times and the cells are still going strong. I haven't logged how many cycles, but I'd guess some of my cells have 300+. I harvested them from a Dell 51510 battery pack. They come off the Pila @ 4.19. Stay above 4.16 for weeks. Run an SC60 for 1 hour 40 minutes on high before cut off.

G27

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

I purchased two Panasonic NCR18650 unprotected cells today (65mm length, 2900 mAh), deciding to pin my hopes on the manufacturer's recommendation. I have the nagging feeling I purchased something dangerous. I don't have a charger yet.

It's very confusing to read that Pila chargers will start fires with unprotected cells, when the author is a moderator and a level 4 supporter with over 10K posts. I'm a novice, so I'm in no position to judge the veracity. See post 7 here, where the author states the Pila shuts off at 4.6V, relying on the battery's built in protection to shut off at 4.2V. That seems illogical to me, but what do I know.

The following post by another big-count poster confirms: "If you are talking about charging an unprotected cell in the Pila charger, don't bother. It *will* overcharge the cell." No following post contradicts these two statements.

But then contradictory evidence found here, where the Pila is said to terminate at 4.20V.

So I'm left scratching my head, wondering what charger to buy. The Pila is universally recommended here on CPF.

I don't want to build a forehead bomb. I just want to use an H60w in peace and harmony with the electrons that fuel it. Who would have thought it would be so complicated and fraught with peril...or at least, REPORTED peril, whether real or not.

I'll admit I'm still pretty darned confused.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Bolster said:

It's very confusing to read that Pila chargers will start fires with unprotected cells, when the author is a moderator and a level 4 supporter with over 10K posts. I'm a novice, so I'm in no position to judge the veracity. See post 7 here, where the author states the Pila shuts off at 4.6V, relying on the battery's built in protection to shut off at 4.2V. That seems illogical to me, but what do I know.

Click to expand...

Look at the date of that post, Pila has long ago revised the charger.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Whew! OK, that makes things much better. Thank you.

Note to self: Buy new, not used.

Re: Confused: Need 'Protected' 18650 if Light Cuts at 2.8V?

Both of my Pilas cut off at 4.2. I've had them for 2 years.

I too was scared to death when I jumped on the LI-Ion bandwagon. I have yet to have any problems.

Make sure you have a good volt meter. Compare readings from a couple different ones as I had one that was consistently .2 volts low....which is a huge difference for Li-Ion.

G27