Go-bag light, 2xCR123A / unprotected flat 18650

terjee

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Hi all,

It's that time of year again, when I kick myself for not being as good as I'd like to at keeping a go-bag ready, and try to do something about it.

One of the things I'm looking to improve, is to have light(s) dedicated to living in that bag. Most of mine keeps moving around, and most of them have at least one thing I don't like for a go-bag light.

Several of the Zebralights would have been excellent choices, but I'd prefer if I could keep dual CR123A in it when it's just sitting idle in the bag. I do have an Eagtac D25LC2 that does take dual CR123A, but it won't take flat-top 18650s, which are my most common fuel source, by far.

Requirements list is something like (not in order):
- rugged and reliable, water resistant, must work when needed
- zero or low standby drain
- twist to disconnect battery is fine, as long as it's still somewhat water resistant
- able to use unprotected flat top 18650
- able to use dual CR123A, fine to need carrier for that
- >200 lumen, more is fine but not needed
- <5 lumen, for runtime
- neutral or warm

Everything else is of lesser importance, spot+spill or floody (but not full flood, or narrow throw) preferably.

Given the use of this light, interface isn't terribly important.

I could go $100 on this if it's justifiable, but would prefer $60-70 or below.

Both wise words in general and specific recommendations would be highly appreciated.
 

archimedes

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Hi all,

It's that time of year again, when I kick myself for not being as good as I'd like to at keeping a go-bag ready, and try to do something about it.

One of the things I'm looking to improve, is to have light(s) dedicated to living in that bag. Most of mine keeps moving around, and most of them have at least one thing I don't like for a go-bag light.
....

Both wise words in general and specific recommendations would be highly appreciated.

For me, I strongly prefer single-cell torches for this particular scenario ....

• Primaries are better for most storage conditions and many usage conditions (temperature, etc)

• Full primaries are better for infrequent / unexpected emergency use (don't have to be charged)

• No worries about cell matching, if 1x

• Two cell setups have more ways to fail (need not one but two good cells, both need to match reasonably well, if you have a partial and an empty you'd need two full cells to replace, etc)

• More powerful setups may be tempting to overuse (waste) output

I also try not to overly "save money" on emergency gear.

If you have a flaky torch and a reliable one, I'd put the good one in the bag, that only gets used when you are already having a "not great" day ... ;)
 
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Woods Walker

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I would get a Armytek C2 though a C1/A1 would run 1XCR123 and 1X18650 (protected and otherwise) with a C2 body. That's what I use in my INCH bag as prefer 1 battery solutions for BOBs.
 

scout24

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I fully agree single cell for all the reasons listed. I have 2 cell/ 18650 lights in each vehicle, but in the shtf bag, an HDS clicky 1x123 and a E1L Outdoorsman with diffuser. Frequent battery rotation may alleviate the mismatch concerns, especially after summer heat or winter cold.
 

terjee

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Many thanks guys!

I agree about all points with regards to single cell, and I actually typically recommend the same, much for the same reasons.

I realize I should probably have focused more on it being a single-18650 light, the CR123As just for standby storage more or less, and that single CR123A would be just as good as doubles.

It'll also live with a Zebralight flashlight and possibly headlamp, each with AA L91 in them, and spares.

The Armytek route does also look interesting.

Many thanks again!
 

scout24

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How about a Malkoff MD2? High/low, fits 18650's, your choice of tint and output level. Keep a dummy 123 cell with it, most M61's will run lower output out of regulation on a single 123 primary in a pinch...
 

Modernflame

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• Two cell setups have more ways to fail (need not one but two good cells, both need to match reasonably well, if you have a partial and an empty you'd need two full cells to replace, etc)

Apologies if this has been asked and answered elsewhere, but how closely does the voltage on two lithium primaries need to match in order to mate a safe pair? One thing I've noticed is that the cell closest to the emitter tends to drain faster and thus has a lower voltage later in the life cycle of the set.
 

terjee

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Apologies if this has been asked and answered elsewhere, but how closely does the voltage on two lithium primaries need to match in order to mate a safe pair? One thing I've noticed is that the cell closest to the emitter tends to drain faster and thus has a lower voltage later in the life cycle of the set.

The goal is to avoid the weaker cell being drained outside spec, so it really depends on more things than just the voltage. Take the cutoff voltage of the light for example. It'll trigger based on the total voltage of both cells under load, so the higher the cutoff is, the bigger the difference in voltage could be.

This also means a half-spent and a full cell wouldn't be a problem - yet. More like a problem waiting to happen.

This is all complicated by the voltage difference getting larger if the weaker cell is nearing depleted, so you can't just do the math directly, which sort of brings us back to the convenience of single cell lights.

I'm sure some rules of thought could be thought out. I could make a pass at it, but let's wait and see if anyone else comes along first.

For my own use, 123a are mostly for shelved standby lights. They get full cells from the same batch, which I'm mostly assuming not to be a problem. If they ever see significant use, the cells could be moved to single cell lights, to live out their last remaining joules there.
 

Modernflame

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Thank you. And I don't mean to derail your thread. Can we boil this down to a rule of thumb? Let's say that despite my meticulous oversight, two unused CR123's from the same batch with the same expiration date differ in initial voltage by zero point X volts. At what point to should I become nervous?

There's obviously some wiggle room, as evidenced by the fact that my 2 x 123 light does not explode when the forward battery drains faster than the rear.

As far as recommendations go, I second the Malkoff MD2. Very versatile. If you're going single cell, I'd have a look at the Elzetta Alpha. Nothing blingy, just reliable lumens within your criteria.
 

terjee

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No worries about derailing, I think it's within the scope of the thread. :)

I'm slightly tired, and I don't want to give bad advice on this, so I'm a bit hesitant to throw out a number, but what I'd do is something like this:

Start by taking into account the voltage under load. The actual difference can be larger than what it appears to be with floating voltage (I can't at the moment recall how big that difference is with CR123As). Then check discharge curves for common CR123As, and try to see about how much difference you'd want to see in charges cells, for the required difference later, when the weaker cell is nearing empty and low voltage protection should kick in, and add margins to that.

Another way to go about it would be to select away cells that are outside of expectations. If a fresh set is +/- 0.05V, and one is 0.2V away, I'd set it aside.

MD2 is starting to look mighty tempting, and thanks for reminding me about Elzetta. I've kept being tempted by Elzetta, but have stayed away since I've mostly focused on 18650s, but if I do get one, maybe combining with wanting one more single CR123A isn't a bad idea. :)
 

mk2rocco

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I went with a MD2, High/Low ring and a M61N. I have 2 18650 batteries, 4 CR123s, and a solar charging setup in my bag.
 

Woods Walker

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Here are my Bug Out Lights. Low voltage omnivores so can't run 2XCR123 however will run 1XAAA in a pinch.

OLMptUo.jpg


Notice the Solar option.

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jgWAKwH.jpg


DmT9NBZ.jpg


Dhkm37e.jpg
 

Woods Walker

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MD2 wouldn't be bad as it can run on 2XCR123 or 18650. The Hi/Lo ring on low runs a loooooooooooooooooooooooong time. MD1.5 on top and MD2 on bottom.

yVCuYCz.jpg


Potted electronics with very little to go wrong.

1ndB6is.jpg
 

Woods Walker

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ECEEN 10W solar panel charger. Hands down the best little panel charger I have tested. Wonderful low light potential and totally immune to charging errors. The chargers are Olight UC magnetic and Xtar MC1 plus. The MC1 plus (not ant version which is almost as good) is overall the fastest 1A charger I tested for solar applications as it constantly charges at 1A if possible (doesn't default to .5A). The Olight UC (and guessing 4/7's version) is just an overall good .75A charger and will do NiMH at .25A pulse charger. Sorry OP for the potential off topic.
 
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Modernflame

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ECEEN 10W solar panel charger. Hands down the best little panel charger I have tested. Wonderful low light potential and totally immune to charging errors. The chargers are Olight UC magnetic and Xtar MC1 plus. The MC1 plus (not ant version which is almost as good) is overall the fastest 1A charger I tested for solar applications as it constantly charges at 1A if possible (doesn't default to .5A). The Olight UC (and guessing 4/7's version) is just an overall good .75A charger and will do NiMH at .25A pulse charger. Sorry OP for the potential off topic.

Thanks! Surprisingly inexpensive.
 
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