How to tell when to use unprotected or protected cells?

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iAmMyOwn
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How to tell when to use unprotected or protected cells?

I have bought the Astrolux C8 and the Astrolux S1. Neither of these flashlights suggest to use protected or unprotected 18650’s.

I would prefer to use unprotected batteries so I can learn how to properly look after them.

My questions are:

  • How can I tell if I am supposed to use protected or unprotected 18650’s if the flashlight does not explicitly specify?
  • Can I use an unprotected cell in a flashlight that says to use protected cells? or would an unprotected cell be too short?
  • Generally if a flashlight takes 18650 cells can I use either unprotected or protected? My main concernt would be that if I used unprotected then it maybe too short to make contact to complete a circut or a protected cell may be too long and not fit

Thankyou!

Edited by: iAmMyOwn on 03/10/2018 - 17:13
hIKARInoob
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Hey how are you and welcome to BLF! Party

Basically, the difference between protected and unprotected cells in terms of compatibility is length that could be a problem for a light. And sometimes slight increase in diameter of a protected cell can be an issue with a light as well.
General rule of thumb that I personally maintain is that a mainstream company like Fenix, Olight, Nitecore or Thrunite is designed for the masses, so these lights are made (more often) for slightly longer protected cells.
A more niche, smaller, or “flashaholic” company like Convoy, Emisar, or Noctigon have the tendency to design their lights for shorter unprotected cells.

So this is my basic rule of thumb. In reality I would check whether a specific light can take protected and or unprotected cells.
To further complicate things, it is also possible that one protected cell fits, but a different one doesn’t. I believe a protected Keeppower 3500 is just a bit thicker than an average protected cell, and I’ve read that the Keeppower specifically wouldn’t fit in a light.

Some examples: The Nitecore TM26GT does not accept unprotected cells, as these are too short. The Emisar D4 and Noctigon M43 don’t accept protected cells; these are too long. Skilhunt H03 and Zanflare F1 both accept protected and unprotected cells.

My guess is, and hopefully others will chime in, that the Astrolux C8 and S1 both take unprotected cells. I’m pretty sure, but I cannot guarantee you this.

Edit:

I think sometimes companies also mention to use protected cells only, but that’s done more for legal reasons.

iAmMyOwn
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thankyou, i am good and have just started gaining an interest in flashlights and batteries.

so the bottom line is that its kind of hit and miss? even if the flashlight just says to use 18650’s without specifying protected or unprotected?

hIKARInoob
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If it’s not specified, then my guess is that it’s most likely compatible for both types. I think the hit or miss situation is more or less an exception; you cannot assume it will always be fine.
The Emisar D4 for example is a very powerful light; it produces in the order of 4000 lumens from a single 18650 cell. This means you need a high drain cell. This means you’re in the realm of unprotected cells, and that’s what the light is made for geometry wise.

… But what we flashaholics do if the batteries don’t fit the light we just bought, is to buy a new light specifically for these batteries Wink

pennzy
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One way to find out is to google the light in question . Usually , a BLF or CPF review will come up . Read the threads to get an idea what will fit.

hIKARInoob
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I just realised both the C8 and S1 have a driver of the type “FET”; this means it performs best with an unprotected cell. So both lights require unprotected high drain cells.

Phlogiston
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I don’t know about the C8, but the S1 is the same design as the BLF A6, which I have, and the A6 works with my EagTac / EagleTac 3500mAh protected 18650 cells. Those cells can supply up to 10A before the protection trips, which is enough for the S1 / A6 (the current draw is about 6A in a stock light).

I understand that most people use unprotected cells for maximum performance, but high current protected cells are still an option for people like me who prefer them.

The only snag is that the battery tube is a bit narrow, so my cells barely fit. Length is fine, width could be an issue. I have six battery tubes in total of that design, and one of them is fractionally narrower than the others, so it doesn’t accept protected cells.

hIKARInoob wrote:
A more niche, smaller, or “flashaholic” company like Convoy, Emisar, or Noctigon have the tendency to design their lights for shorter unprotected cells.

Actually, many Convoy lights are compatible with both protected and unprotected cells, especially the newer designs. I can personally say that protected cells work nicely in my Convoy S2+, X3, BD04 and BD06 lights.

The one place I’ve run into trouble was trying to use Keeppower 6000mAh 26650 protected cells in my BD06, and they wouldn’t fit. That’s not the BD06’s fault though; Keeppower made those cells too wide.

EDIT: almost forgot – the BD04 only accepts shorter protected cells. In my case, EagTac 3500mAh protected 18650s barely go in; Fenix 3400mAh protected cells won’t go in at all.

Unprotected cells fit nicely, however, since they’re automatically shorter. The BD04 design has also been upgraded to Biscotti firmware, which has built-in low voltage protection, so protected cells are less important there.

hIKARInoob
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^^^ Yes you’re right. So it’s a bit complicated, and pennzy’s advise is good; just read the reviews, and surely you will get good battery advise. Also by reading a lot you will develop a “feel” for battery compatibility I think.

Phlogiston
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That is good advice.

TheIntruder
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I’m somewhat of a noob venturing into more “enthusiast” oriented lights, and have a C8 on the way as well.

The most often recommended cells for it seem to be the unprotected Samsung 30Q and Sony VTC6. While there are protected versions available, most are not, and substantially less expensive as well.

For the Astrolux C8, one thing to be aware of is that its direct driver (in the high modes) will have higher current demands on the battery, which calls for a high discharge battery and appropriate protection circuit (if present). The latter will place a constraint on the current available vs. an unprotected cell.

As one example, the Klarus 18GT-IMR31, which appears to be a protected cell based on one of the above cells, is rated to deliver a maximum continuous current of 12A, a cost of 3A over the naked cell. There may be other protected cells out there that can provide the equivalent, or something closer, but I’m not aware of one.

I’m not sure what the C8 typically draws in use, but if 12A is sufficient, then that battery is a suitable candidate, provided it will fit into the body tube. Protected cells tend to be longer, and marginally larger in diameter than unprotected cells. A post elsewhere here cited the Convoy C8’s maximum battery length as 70.5mm.

There’s also the question of margin. Let’s say the C8 will draw 10A in use. Does one opt for the protected Klarus operating at closer to its maximum rating, or something more comfortable with a bare cell?

Aside from the physical dimensions, on balance, the potential compromises in performance, and margin, as well as the extra cost of using a protected cell, firmly favor the use of an unprotected cell in these particular lights.