18650 Storage of New and Used Cells

300WSM

Newly Enlightened
Joined
Mar 11, 2014
Messages
141
Location
Yellowstone Valley
I have six Convoys that I use at home and in my vehicles only from time to time. Most do not see a lot of use. My L4 is used a lot and I change out the battery frequently. The others (S2s, M1 and M2) are stored for long times without use ( I check and run them all frequently to make sure they can operate). They are all loaded with Panasonic protected 18650 batteries. I do not currently use a meter to check them. I bought all of these Convoys years ago an a kick that I was on but they are great flashlight and served me well. Should I change out the 18650s for the 123s for the infrequently used lights or is there a way to setup the 18650 batteries for infrequent use?

Also, what is the best way to store new, still in the box, 18650 batteries that I won't (obviously) need?

I have Eagletacs (AA) in my go bags (I store these with batteries outside the lights) and a Nitecore in my EDC bag (AA) for use on the road and at work. Any thoughts?
 
Last edited:

Lampas

Newly Enlightened
Joined
May 14, 2013
Messages
20
Regarding the storage of 18650s: I think this is a topic well written about, here (link) are some infos to start with. Bottom line: ideally around 70% charged, under 20° Celsius and dry.


How long is "are stored for long times without use"?
I think up to one year it should be no problem, the longer the battery isn't used, the more rapidly it will degrade. The more a battery degrades, the more unstable it gets wich could led to swelling or worst case catching fire/exploding. If your car gets hot often and you use your flashlight just rarely I would definitely consider switching to 123s.



ps: I bought an empty Convoy body once but never found the time to make my own built. should have known better =)
 

terjee

Enlightened
Joined
Jul 24, 2016
Messages
729
Location
Bergen, Norway
-- 18650 / CR123A

LiIon cells will self-discharge, although not as fast as normal NiMHs for example. If you're putting a light in a go-bag or car, for emergencies only, in a "throw in and forget"-way, I'd definitively consider CR123A to be a better option.

If you check it occasionally (4 times a year or more), and there's are no temperature extremes, then 18650 should be just fine as well. Note that it would be better to swap the 18650 4 times a year, to a freshly charged one. They'd still work after all, even if remaining energy isn't what you'd want.

There is a lot of room here for personal preference, and different weighting of pros and cons. My own rule of thumb is that if I'm somewhat confident that I'll check and swap batteries in a light in the next 3 months or so, I'll never consider anything but 18650. If I might forget, such as a go-bag, I'll put in CR123A, and have a fresh set of CR123As stored with the light as well. That way, even if the light has seen some use, I always have a fresh set there. The light would be good to go 3 years later, if I forget.

For passive storage of LiIons, it's best to store them with only a partial charge. Storing them fully charged causes some wear, but letting them self-discharge below empty is even worse. Lots of different numbers floating around, but storing them at a voltage of 3.92V seems to be about ideal. It's low enough to not have the bad effects of storing fully charged, there's useful charge in the cell if you need to use it without charging, and there's a long way of self-discharge before damage. Not critical to be exact, 3.8 is just fine for example. Be below 3.92V rather than above, just don't get too low. I would rather charge a cell than store it at 3.5V for example.

Most of this matters if you want long term storage with minimal loss in capacity. I'd do it for cells I don't plan to use in the next 6 months, for anything in rotation I just charge fully and put in the ready pile.

-- AA

There are thee main types of AA batteries in my book:

- Lithium primaries

Allows for log storage, non-rechargeable. Can be stored in light.

- Low self-discharge (LSD) NiMH (such as Eneloop)

These are great, and pretty reliable. Can be stored in light.

- Alkalines

Not to be stored in light, only used for emergencies.

What I'd do for go-bag type light, is similar to CR123A, of having Lithium in the light, and fresh Lithium ready outside the light. No harm having Eneloops (or similar) in the light, and as extras, but do keep some Lithium as well.

My preferred choice would probably be Eneloops in them, and then Lithium extras, that would be somewhat reserved for emergencies. Replaced with fresh if ever used.

If you're tempted to have a bunch if alkalines for extended power outage or similar, I'd much rather recommend a pile of CR123A. Lithium primary AA would be fine, but is almost always more expensive. Personally I buy 10-20 CR123A a year, and use none. Adds up. :)
 

300WSM

Newly Enlightened
Joined
Mar 11, 2014
Messages
141
Location
Yellowstone Valley
-- 18650 / CR123A

LiIon cells will self-discharge, although not as fast as normal NiMHs for example. If you're putting a light in a go-bag or car, for emergencies only, in a "throw in and forget"-way, I'd definitively consider CR123A to be a better option.

If you check it occasionally (4 times a year or more), and there's are no temperature extremes, then 18650 should be just fine as well. Note that it would be better to swap the 18650 4 times a year, to a freshly charged one. They'd still work after all, even if remaining energy isn't what you'd want.

There is a lot of room here for personal preference, and different weighting of pros and cons. My own rule of thumb is that if I'm somewhat confident that I'll check and swap batteries in a light in the next 3 months or so, I'll never consider anything but 18650. If I might forget, such as a go-bag, I'll put in CR123A, and have a fresh set of CR123As stored with the light as well. That way, even if the light has seen some use, I always have a fresh set there. The light would be good to go 3 years later, if I forget.

For passive storage of LiIons, it's best to store them with only a partial charge. Storing them fully charged causes some wear, but letting them self-discharge below empty is even worse. Lots of different numbers floating around, but storing them at a voltage of 3.92V seems to be about ideal. It's low enough to not have the bad effects of storing fully charged, there's useful charge in the cell if you need to use it without charging, and there's a long way of self-discharge before damage. Not critical to be exact, 3.8 is just fine for example. Be below 3.92V rather than above, just don't get too low. I would rather charge a cell than store it at 3.5V for example.

Most of this matters if you want long term storage with minimal loss in capacity. I'd do it for cells I don't plan to use in the next 6 months, for anything in rotation I just charge fully and put in the ready pile.

-- AA

There are thee main types of AA batteries in my book:

- Lithium primaries

Allows for log storage, non-rechargeable. Can be stored in light.

- Low self-discharge (LSD) NiMH (such as Eneloop)

These are great, and pretty reliable. Can be stored in light.

- Alkalines

Not to be stored in light, only used for emergencies.

What I'd do for go-bag type light, is similar to CR123A, of having Lithium in the light, and fresh Lithium ready outside the light. No harm having Eneloops (or similar) in the light, and as extras, but do keep some Lithium as well.

My preferred choice would probably be Eneloops in them, and then Lithium extras, that would be somewhat reserved for emergencies. Replaced with fresh if ever used.

If you're tempted to have a bunch if alkalines for extended power outage or similar, I'd much rather recommend a pile of CR123A. Lithium primary AA would be fine, but is almost always more expensive. Personally I buy 10-20 CR123A a year, and use none. Adds up. :)

In your answer, you quoted levels of battery voltage. Can you recommend a good volt meter? I already own a Volt meter that I use for car batteries, house current, etc. Would this work? :sssh:
 

SilverFox

Flashaholic
Joined
Jan 19, 2003
Messages
12,449
Location
Bellingham WA
Hello 300WSM,

Any voltmeter will work for general readings. If you need accuracy you would then look at more precise voltmeters.

Tom
 

terjee

Enlightened
Joined
Jul 24, 2016
Messages
729
Location
Bergen, Norway
What he said. :)

Even a $2 meter off of eBay would probably get the job done. If you'd want to get things 100% right, it would be best to test the cells while under load, and some battery testers will do that. It makes little or no practical difference though, so I wouldn't recommend spending money on it. What you can do instead is to just run the light that the batteries are in for 15 seconds or so, if you're checking a battery in a light, if they've been out of use for a while.
 
Top