Malkoff M60 with unprotected 18650s?

[etc]

Most LED lights contain some form of regulation, but not all do. Those that are regulated, can and will severely over-discharge an unprotected cell long before you have any feedback in the form of noticeable dimming or shutdown to let you know.

Does that mean that an unprotected 18650 such as Samsung 2800 mAh or Panasonic 2900 mAh will not work well in a Malkoff M60 2x18650 lite?
That I won't see any dimming at all as the voltage drops?

I have a Pila charger that stops charing at 4.2V so I am not afraid of overcharge, but overdischarge?


http://18650.cn/index.php/Catalog/PANASONICNCR186502900mAh

 

[Kestrel]

A lot has been written on this, I'm surprised you haven't come across this info in your 4 years here. Try the search function instead of starting another thread.

 

[mdocod]

The input voltage is 3.8 - 9 volts. Below 3.8 volts it will drop out of regulation and run direct drive.

click this link: http://industrial.panasonic.com/www-data/pdf/ACA4000/ACA4000PE1.pdf

pay special attention to section "2-3"

Eric

 

[etc]

"Equip the unit with a mechanism to prevent overdischarge"

don't discharge beyond 2.75V if 2x18650 series.

Translation: Not going to work with M60 since it's regulated, my guess is you won't notice that they are overdischarged until it's too late.

Looks like protected is the way to go, either AW or Pila, or some DX brand. Not many choices and none above 2200 mAh (even if claimed otherwise)

 

[mdocod]

A+

To elaborate now: 2 cells, in series, discharged to the point where you would see dimming on an M60, would be well under 2V per cell.

CPF member FallingWater has had good luck with the "trustfire" brand 2500mAH protected 18650s. It's just one persons experience, but overall, there seem to be less trustfire complaints than other "fire" brands on the forums, and those 2500mAH cells have proven in testing to have more capacity than AW 2200 cells.

A few years ago, to get M60 performance for ~ 4 hours (currently possible in a 2x18650 body) would require a 4D mag with 4 D size NIMH cells and triple LuxIII custom setup. You're searching for the holy grail of li-ion cells, but for your application, you basically already have it. Yes it would be nice to have access to some 2900mAH cells with protection circuits, but unless we come up with a group buy that demands a million units, it's not likely going to happen really soon. Just accept the fact that li-ion cells with flashlights in mind are going to be a couple years behind the latest trend for that cell type.

 

[etc]

From Mr. Malkoff himself:

quote:

If you use unprotected cells it will probably drain them to the point of no return. I doubt that you would notice a drop in ouput before its too late.

 

[kyhunter1]

Do yourself a favor and get some protected cells. Unprotected cells work just fine, but sometime or another you will overdischarge and ruin them. They will not harm your M60.

 

[etc]

What about the 1x18650 + M60 configuration?

You get 1.5 hours of regulated lite, at which point it drains down to 3.8V.

Beyond that it starts dimming, unlike the 2x18650 version.

Is it safe to get one of these new Panasonic 2900 mAh cells and run it in the 1x18650 configuration? And just remove the cell when it's pretty dim, still keeping it above 2.5V?
Can you visually detect when it gets "too dim"?

At 2.5V, it has to be *very* dim, because I tried running M60 on 3V (via 2xAA) and it was very dim.

 

[mdocod]

Hi etc,

Yes- for a single cell, you could get away without a protection circuit and more than likely do just fine. Many people use unprotected cells in incan applications and kill the light at the first sine of sudden dimming and the cells do pretty well. -and YES, the M60 should get very dim when the power supply voltage starts approaching or dropping below 3V. Only major disadvantage here is that if the light is accidentally left on for a long period of time, the slow drain rate at ~3V and below would suck the thing pretty dry...

Make sure to use a charger that you trust with unprotected cells.

 

[etc]

This is what I thought -- thanks for confirming. I do have a number of AW's protected cells, both in 2200 mAh and the newer 2600 mAh configuration but reserve for the use in the 2x18650 configuration.

Malkoff M60 is very dim even at 3V. Not sure how to quantify "very dim" but it's dimmer than 1W lites from about 5 years ago. Surely you can tell that apart from the full blast of M60 at 235 lumens.

I use Pila ICB.. nice charger. It doesn't go beyond 4.2V.

LiCo02 cells should not be discharged below ~3.0V under a load, (varies by manufacture). A good rule of thumb is that when the cell reaches ~3.5V open circuit, it is dead and should be recharged. Over-discharging a cell will increase the rate of internal oxidation leading to reduced capacity, reduced cycle life, and increased likelihood of explosion/fire. Different cells are rated for different maximum discharge rates, usually specified between 1.5 and 2C. (C ratings are having to do with time, a 2C rating, means 30 minutes, 1C means 1 hour, 4C means 15 minutes, 0.5C means 2 hours, etc etc, bigger C). Check to see what your cells are rated at and use them in an application that is within the bounds of the maximum discharge rate.