Protected vs unprotected 18650 battery

In another thread I read the reply to "where to find 18650s in Canada" the reply said you don't need protected batteries. Can someone explain more on this or post some links?

I just got my first 18650 light MH23 and Nitecore 3500 8 amp, Its protected. I thought all lithium cobalt batteries needed protection while Mn and iron phos lithium's did not? Also I thought the cobalt held a larger charge?

If your light does not have low voltage protection, and as long as one is not pulling more than an amp or two, protected cells are safer, since they will not let a cell be drained low enough to be damaged. In lights that do have low voltage protection, and/or ones that pull higher currents, un-protected cells work find. When one gets up into the INR and IMR cells due to the current draw, it is almost impossible to find a protected cell, since most available protection circuitry can't handle the higher currents.
And yes, due to the space taken up by the protection circuit, an unprotected cell will usually have a slightly larger capacity than a protected one.

In the bad old days we were powering incandescent lights with li-ion. Typically several li-ion in series. When cells are in series it is easy for an imbalance to destroy a cell. So protection was smart. And an incandescent bulb can easily run a battery down to zero volts. Protection was needed to that case too. And some of the chargers were horrible and would try to overcharge li-ion cells. Protection would save your butt there too. And all of the old cells were ICR (lots of cobalt) and these cells were the most temperamental and the easiest to make catch fire.

Now though things are a little different. ICR is barely a thing any more. Of the 18650s in my battery database less than 5% of them are ICR. Instead more resilient modern chemistries like IMR and INR make up most of the cells you can buy. These still don't like being overdischarged but they are much less likely to fail catastrophically.

LED flashlights are vastly different from incans in their power draw. An LED light is basically incapable of running a battery down to zero. Even getting a battery down to 2.5V with an LED takes a lot of patience. You have to run the lowest mode for days on end and none of the other modes will work.

Chargers are vastly better now. Even the cheapest ultrafire charger won't overvolt cells.

Protected batteries are still a good idea in a light that runs multiple cells in series. And if you are extremely worried about direct shorts the protection circuit is a layer of defense. But other than that most of the old reasons don't apply.

I cannot contribute anything after those two magnificent posts.
I shall only give you my favourite quote...
"The protection is there to protect the cell against you, not the other way round".

P

peter yetman said:

I cannot contribute anything after those two magnificent posts.
I shall only give you my favourite quote...
"The protection is there to protect the cell against you, not the other way round".

P

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I agree, thank you to all!

Timothybil said:

And yes, due to the space taken up by the protection circuit, an unprotected cell will usually have a slightly larger capacity than a protected one.

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Not quite true. Protection circuits DO take up extra space. But protected cells don't use special small capacity cells to make up for the size of the PCB. The heart of a protected cell is simply a bare, unprotected cell. In other words, protected cells are of the same capacity as unprotected cells (provided they use the same bare cell). But protected cells are just larger because the circuit is added on to the size of the cell. This, of course, can create fitment issues when using them.

If you are using those cheap Chinese flashlights, which I do because I always seem to drop them, I'd highly recommend using a protected battery. Other more expensive flashlights have their own protection circuit (or chip rather) and can use unprotected batteries just fine and dandy. The plus side for unprotected is that they can deliver much more power (a.k.a. amps) and they are much cheaper as well because they dont have any protection built in.

When I purchased my Nitecore EC4SW, I was disappointed that it discharged so quickly just sitting around. It came with two Eastshine 18650 protected cells that seemed to be good quality (green MJ1 LG 3500mAh underneath). The light seemed to draw 60uA while off. Every time I went to use it, it was nearly dead, so I started leaving the cells outside the light which is a big PITA. But last night I put them in the light and it didn't work. Cells measured 2.75v!!! So in just a couple months, the protected cells killed themselves?

I think I'll go back to unprotected cells and see what happens with this light. Maybe it will be useful afterall.

markr6 said:

When I purchased my Nitecore EC4SW, I was disappointed that it discharged so quickly just sitting around. It came with two Eastshine 18650 protected cells that seemed to be good quality (green MJ1 LG 3500mAh underneath). The light seemed to draw 60uA while off. Every time I went to use it, it was nearly dead, so I started leaving the cells outside the light which is a big PITA. But last night I put them in the light and it didn't work. Cells measured 2.75v!!! So in just a couple months, the protected cells killed themselves?

I think I'll go back to unprotected cells and see what happens with this light. Maybe it will be useful afterall.

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If it was just one of your cells, I'd say it was a bad cell. But both? That sounds like they're using some really crappy protection circuits. It shouldn't be drawing more than a few microamps, at most.

WalkIntoTheLight said:

If it was just one of your cells, I'd say it was a bad cell. But both? That sounds like they're using some really crappy protection circuits. It shouldn't be drawing more than a few microamps, at most.

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I guess that's why the math wasn't working out. 60uA draw on the light itself, while not great, wasn't terrible either. I'm going to try some of the Evva cells from Mountain Electronics. I'm sticking with protected since even my 18650GA's wern't long enough to work in the EC4SW. They rattled a lot anyway even with a thick wrapper and button top. It's a strange light.

markr6 said:

I guess that's why the math wasn't working out. 60uA draw on the light itself, while not great, wasn't terrible either. I'm going to try some of the Evva cells from Mountain Electronics. I'm sticking with protected since even my 18650GA's wern't long enough to work in the EC4SW. They rattled a lot anyway even with a thick wrapper and button top. It's a strange light.

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You could try putting a small magnet on the cell if it's not long enough. As long as there isn't a chance it will move around to where it might short something inside the light.