Protected vs unprotected 18650s - observations

After using these for over a decade, these are my thoughts:
I love unprotected 18650s for 2 reasons: 1. They decline gradually, slowly get to zero or the point where the light isn't getting enough voltage to even run. If you know your curve, you can kind of visually estimate when it's about 3.5V and time to recharge. I've done so for many years. 2. They are more reliable, theoretically, with no PCB circuit to fail.

The thing about protected cells, you need them for multi-cell lights as the above tactic no longer works. Voltage compounds and a 3-cell light on depleted cells down to 2.5V still compounds to 7.5V and may light up the module, causing damage, or so the theory goes.

*The* problem with protected cells is they cut off suddenly, leaving you in the dark, maybe in a critical situation. Imagine yourself caving, or being in a critical situation with an intruder or such. The lights goes poof and goes from 100MPH to zero in a nanosecond. You may have a reload but.

For critical situations, I would use a single 18650 or an MD4 with 4x123 cells as they just don't die like so and gradually cruise to a stop. I think that's what many overlook. dual protected 18650s are fine around the house but maybe not the best for a trip where you totally need the light with zero downtime. That's why there is still a place for 123s, sometimes. Of course there is nothing wrong with 1x18650 either. When I travel, I take an MD3 loaded with 18500s but in a mission critical situation, load it with 123s.

Does anyone run MD4 Hound Dog or anything else 2x18650 on unprotected cells?

Kind of. But if you use a regulated flashlight (such as a zebralight), the brightness doesn't decline as the voltage drops. Eventually, the light will just suddenly drop down to low output (when the voltage gets down to 2.9v). It will still run for a long-time, though, so yeah, it's definitely better than the protection circuit shutting off the battery. IIRC, when the resting voltage gets down to 2.7v, the zebralight will shut off completely.

I use matched pairs of unprotected IMR cells in my MD4 HD, ever since I was left in the dark on protected.
I tend to buy the cells in batches of four and run a charge / discharge / charge test and pair up the ones that closest match. when I recharge them after use, the charge amounts on each cell are within about 1% - that's good enough for me.

Say goodbye to left in the dark by protected cell misery.
P

peter yetman said:

I use matched pairs of unprotected IMR cells in my MD4 HD, ever since I was left in the dark on protected.
P

Click to expand...

LOL yeah! or you get that Disco effect if it`s in an Incan, the voltage drops the bulb goes out, the voltage sag stops and the bulb comes back on again for a sec and starts over again, not great when you`re under a desk tangled in a bunch of audio/midi cables thicker than your arm.

that much is understood, if the protection circuit does not kick in, it runs until the LED module itself can no longer power itself with what's is remaining. It's the outer boundary of power. Panasonic 3500 mAh "GA" can run until 2.5V so its cut off voltage is pretty low.

This is why I've moved to a single cell paradigm. I currently do not own a multiple li-on set up.

I've got my eye on a Malkoff Wildcat 18650. Looks like he finally built my dream light.

Perhaps Santa will drop one under the tree this year.