Battery Storage vs Keeping them in Flashlight advice.

Perhaps I'm overly conservative, but I consider 4.1v to be a full charge. I don't store lithium ion cells at this voltage for more than a couple of weeks. If I need something to be at the ready long term, then I use lithium primaries.

In practice, this means I only use a few 18650's at a time, while most of them are in long term storage @ ~3.7v. I don't fear my lithium ion cells, but I respect them. This is part of my safety strategy. An explosive, thermal runaway event has shaped my perspective.

The direct answer to your question is that there will be very little in the way of self discharge when starting at 4.1, as opposed to 4.2v.

Depends on ambient temperature.

Storage at 4.1V will be (a liitle) better than 4.2V ... but (substantially) worse than 3.7V

Modernflame said:

Perhaps I'm overly conservative, but I consider 4.1v to be a full charge. I don't store lithium ion cells at this voltage for more than a couple of weeks. If I need something to be at the ready long term, then I use lithium primaries.

In practice, this means I only use a few 18650's at a time, while most of them are in long term storage @ ~3.7v. I don't fear my lithium ion cells, but I respect them. This is part of my safety strategy. An explosive, thermal runaway event has shaped my perspective.

The direct answer to your question is that there will be very little in the way of self discharge when starting at 4.1, as opposed to 4.2v.

Click to expand...

Did you get thermal runaway because the batteries drained too much? I'm cautious too, that is why I started this thread as I'm not sure about leaving them in the flashlight or not for too long.

Something to note is that every flashlight is different. No electronic device is the same. They are all going to have varying amounts of parasitic drain. The Emisar D1/S have really high parasitic. While my new model Zebralights parasitic drain is very low.

I personally own 18650s to use them. I have two main lights and I have 4 18650 batteries i keep fully charged. I run them down to about 3.2-3.6, charge them and they are back in their holders.

For peace of mind keep a few in long term storage. Just don't turn your hobby into a boring worry fest

klrman said:

Did you get thermal runaway because the batteries drained too much? I'm cautious too, that is why I started this thread as I'm not sure about leaving them in the flashlight or not for too long.

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Most likely an internal short. I use 18650's despite this experience and I don't live in fear. Still, my safety strategy involves diligence. You could probably leave them @ 4.1v inside a device for a long time without incident. I just don't go there.

I use mine too much to even worry about it. Kill them, swap out, charge, rotate and use them all over again and again in a constant cycle.

The lights I've got, don't seem to drain them any faster stored in less used lights compared to ones stored waiting to be used. My most used lights use 18650 cells and both seem to be easy on them running long. One uses two and the other is a single. Just a continuous cycle.

I have one light that uses in light charging. My Olight S1R cell has been run dead just over 100 times and fully charged over 100 times. I can't notice any difference in performance at all, including run time. Ambient temps effect run time more than the 100+ killing and charging cycles.

When a battery dies, it's replaced. They make new ones everyday.

I don't use flashlights that require multiple cells so I don't have to worry about matching cells.

I keep all my cells topped off so that I don't have to worry about shorts developing in the electrolyte. This causes them to "age" faster, but I totally don't care since they don't age in a way that makes them dangerous by themselves the way sitting while discharged can. It just reduces their capacity. Once I notice decreased run time, then I simply purchase new cells.

Actually, that last sentence is a lie. I've been using the same 2 16340 cells since 2010 and haven't noticed any issue with reduced capacity yet. I'm sure that they have reduced capacity, but I mostly use low output levels and can still go a month before swapping cells. I used to keep a log of when I swapped cells and what the start/end voltages were, but I gave that up years ago. I have just recently purchased new cells, but that is because I have more lights in rotation now.

--flatline

I appreciate all the input everyone, thank you very much. So far I only have protected cells and want to use them as much as I can when needed. I don't want to have a collection of flashlights sitting on my shelf barely getting used. I guess the main thing is not to let them drain too low, so that is easy to keep an eye on with my dmm.

I've learned from experience what lights I've got don't equally pull batteries down in voltage.

Nitecore with the Tiny Monster lights pulls voltage off of two of the four cells causing an unbalanced voltage drop. Same goes for the P36 light.

The Tiny Monsters you can brake the ground circuit by unscrewing the tube a turn or two. The P36 uses a magazine and as such, as long as batteries are inside, the light draws current.

It's too bad on the P36 as the user interface is better than the Fenix TK35. The scroll wheel for changing brightness is a good idea. As it stands, the batteries sit in a case clipped to the light fully charged.

With the cost of quality 18650 batteries being as low as they are if I get four years out of a set of batteries, I'm happy.

JoeRodge said:

Something to note is that every flashlight is different. No electronic device is the same. They are all going to have varying amounts of parasitic drain. The Emisar D1/S have really high parasitic. While my new model Zebralights parasitic drain is very low.

I personally own 18650s to use them. I have two main lights and I have 4 18650 batteries i keep fully charged. I run them down to about 3.2-3.6, charge them and they are back in their holders.

For peace of mind keep a few in long term storage. Just don't turn your hobby into a boring worry fest

Click to expand...

You do realize that the parasitic drain on an Emisar D1S (and probably the D1 and D4) is listed at .02mA, so a 3000mAh 18650 cell will take about 17 years to drain down to 0.0v.

I'm no EE, but that seems pretty good to me, no?

http://budgetlightforum.com/node/57031

Just sayin'.

Chris

ChrisGarrett said:

You do realize that the parasitic drain on an Emisar D1S (and probably the D1 and D4) is listed at .02mA, so a 3000mAh 18650 cell will take about 17 years to drain down to 0.0v.

I'm no EE, but that seems pretty good to me, no?

http://budgetlightforum.com/node/57031

Just sayin'.

Chris

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Dang! I was basing that off experience and not data. Might just be time to get new cells.

Protection from accidentally turning the light on, and knowing that it will come on at the highest regulated level (350mA?) is enough reason for me to keep Emisars slightly unscrewed, so parasitic drain isn't even an issue that makes the list.

eh4 said:

Protection from accidentally turning the light on, and knowing that it will come on at the highest regulated level (350mA?) is enough reason for me to keep Emisars slightly unscrewed, so parasitic drain isn't even an issue that makes the list.

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You do know that there's a lock-out feature in the firmware, don't you?

I was working in Jeans last month and my D4 did come on in my pocket, but those two occasions are rare and I can always lock it out if I work in jeans again.

Parasitic drain and pocket turn-ons are two things that really shouldn't be a problem with the three Emisar lights.

Chris

eh4 said:

Protection from accidentally turning the light on, and knowing that it will come on at the highest regulated level (350mA?) is enough reason for me to keep Emisars slightly unscrewed, so parasitic drain isn't even an issue that makes the list.

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I have an occasional problem with my Imalent DX80 that with the slightest movement on the switch in lock out mode it will all of a sudden burst into the 32,000 lumens high mode. Happened quite a few times that when I carry it in a pack or holster I mechanically lock it out for peace of mind.