Concerning 18650 cells, at what point do you say "OK, time to retire it"?

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xevious
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Concerning 18650 cells, at what point do you say "OK, time to retire it"?

I understand that some of the best 18650 cells can last up to around 500 charge cycles, with average ones coming in around 300~400. Of course, an 18650 cell isn’t going to tell you how many charge cycles it has in its history, unlike a laptop battery pack that manages an array of 18650 and can store meta data communicated to a laptop diagnostic program.

In general, at what point do you retire your 18650 cells? I’m guessing that a good sign of a battery underperforming is when the resting voltage notably drops within a specific time period (e.g. 0.5 volts in less than 2 weeks). I don’t really have a need to invest in a specialized battery tester that can show estimated mAh capacity (my consumption of batteries isn’t high enough to justify spending $75~150 on a quality tester that can accurately show this info). So I’m guessing that if an 18650 cell is charged to 4.19v and it can’t stay above 4.16v within 2 weeks, then it’s probably time to retire it. Does that sound about right?

Edited by: xevious on 10/20/2021 - 17:06
Bort
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High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

The Journal of Alternative Facts TM

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zoulas
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3 years, regardless of charge cycles.

CollectEverything
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Bort wrote:
High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

At what point is internal resistance too high? Does that depend on the current rating of the cell?

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Bort
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CollectEverything wrote:
Bort wrote:
High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

At what point is internal resistance too high? Does that depend on the current rating of the cell?

It gets overheated during charging is a pretty good indicator.
I had some used laptop pulls that worked great for years but then all started overheating badly.

zoulas wrote:
3 years, regardless of charge cycles.

All of my batteries are older than this, heck i have some that are almost 10 years old (and still testing at near 100% capacity).
I’d love to have your old cells for some testing and use if they are still good.

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

zoulas
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Bort wrote:
CollectEverything wrote:
Bort wrote:
High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

At what point is internal resistance too high? Does that depend on the current rating of the cell?

It gets overheated during charging is a pretty good indicator.
I had some used laptop pulls that worked great for years but then all started overheating badly.
zoulas wrote:
3 years, regardless of charge cycles.
All of my batteries are older than this, heck i have some that are almost 10 years old (and still testing at near 100% capacity). I’d love to have your old cells for some testing and use if they are still good.

I have batteries older than 10 years. Does not mean I would recommend it. 3 years and 80% life is gone. There are external factors that a DMM cannot account for.

If they were $1000 each, I would stretch every minute out of them. But not for $5. I have better things to do than try to bring dead batteries from the dead.

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zoulas wrote:
Bort wrote:
CollectEverything wrote:
Bort wrote:
High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

At what point is internal resistance too high? Does that depend on the current rating of the cell?

It gets overheated during charging is a pretty good indicator.
I had some used laptop pulls that worked great for years but then all started overheating badly.
zoulas wrote:
3 years, regardless of charge cycles.
All of my batteries are older than this, heck i have some that are almost 10 years old (and still testing at near 100% capacity). I’d love to have your old cells for some testing and use if they are still good.

I have batteries older than 10 years. Does not mean I would recommend it. 3 years and 80% life is gone. There are external factors that a DMM cannot account for.

If they were $1000 each, I would stretch every minute out of them. But not for $5. I have better things to do than try to bring dead batteries from the dead.


80% life gone?
How is that happening?

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

zoulas
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Bort wrote:
zoulas wrote:
Bort wrote:
CollectEverything wrote:
Bort wrote:
High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

At what point is internal resistance too high? Does that depend on the current rating of the cell?

It gets overheated during charging is a pretty good indicator.
I had some used laptop pulls that worked great for years but then all started overheating badly.
zoulas wrote:
3 years, regardless of charge cycles.
All of my batteries are older than this, heck i have some that are almost 10 years old (and still testing at near 100% capacity). I’d love to have your old cells for some testing and use if they are still good.

I have batteries older than 10 years. Does not mean I would recommend it. 3 years and 80% life is gone. There are external factors that a DMM cannot account for.

If they were $1000 each, I would stretch every minute out of them. But not for $5. I have better things to do than try to bring dead batteries from the dead.


80% life gone?
How is that happening?

It’s all zeros and ones. If you get too many zeros, it reduces the life.

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When :
A) They self discharge
B) Refuse to take a charge – ( See C )
C) Voltage sag too much after re charging
D) DO a thermal run away … ( Try to explode ) I think I have had two of those over the last 15 or so years . Usually my fault cos I caused a short .

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

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zoulas wrote:
Bort wrote:
zoulas wrote:
Bort wrote:
CollectEverything wrote:
Bort wrote:
High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

At what point is internal resistance too high? Does that depend on the current rating of the cell?

It gets overheated during charging is a pretty good indicator.
I had some used laptop pulls that worked great for years but then all started overheating badly.
zoulas wrote:
3 years, regardless of charge cycles.
All of my batteries are older than this, heck i have some that are almost 10 years old (and still testing at near 100% capacity). I’d love to have your old cells for some testing and use if they are still good.

I have batteries older than 10 years. Does not mean I would recommend it. 3 years and 80% life is gone. There are external factors that a DMM cannot account for.

If they were $1000 each, I would stretch every minute out of them. But not for $5. I have better things to do than try to bring dead batteries from the dead.


80% life gone?
How is that happening?

It’s all zeros and ones. If you get too many zeros, it reduces the life.


In English?

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

Sidney Stratton
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My MiBoxer and Vapcell chargers measure the IR and charge accordingly. So no way I can see them overheating if the chargers are just pushing a few Watts. But I do have noted the IR when new and periodically check. If I see a 50% increase there, I re-test and confirm. Then they are tossed in the low bin (just in case I do need a low valued cell for testing a circuit or light). But that scenario hasn’t come up yet with my better OEMs, only those “economical” pulls from miscellaneous power packs.

xevious
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Yes, most definitely if a cell became very warm or even hot to the touch, that would be an immediate indicator of a dangerous cell ready for recycling. But do all cells do that once they’re worn out?

As an aside, I found this interesting page where the author claims that when cells go into deep discharge and most battery chargers will reject them, there’s a way to possibly recover them. Bring them back up slowly to the voltage threshold (might be like 3.5v) and a charger will then be able to charge back up to maximum capacity. LINK.

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Sidney Stratton wrote:
My MiBoxer and Vapcell chargers measure the IR and charge accordingly. So no way I can see them overheating if the chargers are just pushing a few Watts. But I do have noted the IR when new and periodically check. If I see a 50% increase there, I re-test and confirm. Then they are tossed in the low bin (just in case I do need a low valued cell for testing a circuit or light). But that scenario hasn’t come up yet with my better OEMs, only those “economical” pulls from miscellaneous power packs.

Interesting charger but it would just hide this problem.
I would personally use a regular charger at least occasionally so you can spot this problem on old cells. Aim for 0.33-0.5C charging on this charger so a very low charge rate doesn’t hide the problem.

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

Bort
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xevious wrote:
Yes, most definitely if a cell became very warm or even hot to the touch, that would be an immediate indicator of a dangerous cell ready for recycling. But do all cells do that once they’re worn out?

As an aside, I found this interesting page where the author claims that when cells go into deep discharge and most battery chargers will reject them, there’s a way to possibly recover them. Bring them back up slowly to the voltage threshold (might be like 3.5v) and a charger will then be able to charge back up to maximum capacity. LINK.


Below 2.5V cells can start forming internal dendrites, the may be fine once recovered for months or years then burst into flames of these dendrites grow and puncture the cell internally.
So once it goes below 2.5V the cell is done, no matter how old or new.

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

zoulas
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I use an age based replacement system, not a symptom or status based system. Works for me. A battery can one day save your life so I like to leave as little as possible to chance.

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zoulas wrote:
I use an age based replacement system, not a symptom or status based system. Works for me. A battery can one day save your life so I like to leave as little as possible to chance.

As i said i would be interested in testing your used batteries to see the 80% drop, even my heaters were at about 50% capacity.

The Journal of Alternative Facts TM

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MoreHiCRILumens
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I got something like maybe 8 years old NCR18650B’s which has internal resistance under 0,1 Ohm, or that’s what charger says, but they still have capacity of 3000-3300 mAh. Still good to go. Thumbs Up

xevious
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Bort wrote:
Below 2.5V cells can start forming internal dendrites, the may be fine once recovered for months or years then burst into flames of these dendrites grow and puncture the cell internally.
So once it goes below 2.5V the cell is done, no matter how old or new.
Would a protected cell make any difference?
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zoulas wrote:
I have batteries older than 10 years. Does not mean I would recommend it. 3 years and 80% life is gone.

?!?

I’ve got ancient laptop-pulls (mostly panny-As), from laptops that were used Every Single Day and probably charged accordingly, and while capacity might be down, they still don’t roast when charging, and have at least half their capacity left.

In low-stress lights, they’re perfectly fine.

I’ll usually charge at 1A, and if the cell doesn’t get too warm, it’s fine in my book.

I have had cells (usually those recycled/rewrapped “free” cells from craplights) that did get quite warm, so nope, they’re gone.

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Bort wrote:
zoulas wrote:
Bort wrote:
zoulas wrote:
Bort wrote:
CollectEverything wrote:
Bort wrote:
High internal resistance.
If it overheats upon charge or discharge it goes bye bye.

I have had cells that got too hot to hold during charging.
Capacity loss matters but its more of an indication that more capacity loss is coming., If it does what you need at the lower capacity thats great but expect it to lose even more capacity fairly quickly.

At what point is internal resistance too high? Does that depend on the current rating of the cell?

It gets overheated during charging is a pretty good indicator.
I had some used laptop pulls that worked great for years but then all started overheating badly.
zoulas wrote:
3 years, regardless of charge cycles.
All of my batteries are older than this, heck i have some that are almost 10 years old (and still testing at near 100% capacity). I’d love to have your old cells for some testing and use if they are still good.

I have batteries older than 10 years. Does not mean I would recommend it. 3 years and 80% life is gone. There are external factors that a DMM cannot account for.

If they were $1000 each, I would stretch every minute out of them. But not for $5. I have better things to do than try to bring dead batteries from the dead.


80% life gone?
How is that happening?

It’s all zeros and ones. If you get too many zeros, it reduces the life.


In English?

Yeah, I’m kind of at a loss as to how a cell might need to be tortured’n‘abused to get that worn down.

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Lightbringer wrote:

Yeah, I’m kind of at a loss as to how a cell might need to be tortured’n‘abused to get that worn down.

Too many zeros.  ;)

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Bort wrote:
Interesting charger but it would just hide this problem. I would personally use a regular charger at least occasionally so you can spot this problem on old cells. Aim for 0.33-0.5C charging on this charger so a very low charge rate doesn’t hide the problem.

Why would I use a cheap charger? And the whole purpose of having a charger measure IR and charge consequently is for hassle-free operation. Those economical chargers seldom do more than 1 amp which is too low for my cells and my patience. I mean charging 4 × 30Qs or VTC6s individually at 1 amp was taking me some 12 to 24 hours. And the trouble of monitoring and changing the cells. That is the whole purpose of having a 4 bay unit to quickly bring these up.
And as my collection grew, I didn’t want to spend time charging the various cells I used in the day so I got a second charger. Again, for simplicity and speed.

Are you implying a ⅓C charge rate (1 amp w/3000mAh) can heat a worn-out cell? Or the fact the charger changes the rate of charge if the cell heats up. But the latter I didn’t mention. Geez, I’ve been charging at 2 to 3 amps (auto selection) and if I was to see less than 1 amp, I’d check the IR.

I’m not trying to extend battery life. A cell is to be to my expectations and when they show fatigue, they’re replaced.

BTW this is in the context of the 18650s, the 21700s, and the 26650s. My smaller cells auto-charge rate. I expected them to not last as long in cycles being less capacity. But my Sanyos (14500s) are doing fine after 2 years at about 2 recharges per week. In 2 more years will see if capacity is lost.

I get it you may. have the time and inclination to pamper your cells. My working lights have to be dependable and I don’t skim on the batteries. There is an underlying psychology of turning the light on/off from one peak to another, mentally conditioned to extend battery life. The introduction of rechargeable batteries with high capacity and no memory effect should alter this behaviour. I turn the light on and when temporarily not in need, lay or cover the face. I don’t play with the switch. If the light becomes warm, tone down the intensity. I work with gloves and 50ºC is acceptable. If the light gives a low battery signal, I replace it or pull out another light. Always have a backup.

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xevious wrote:
Bort wrote:
Below 2.5V cells can start forming internal dendrites, the may be fine once recovered for months or years then burst into flames of these dendrites grow and puncture the cell internally.
So once it goes below 2.5V the cell is done, no matter how old or new.
Would a protected cell make any difference?

If the protection cuts the cell output before its dangerous then it should be fine.
Though i would toss it on the charger quickly becasue keeping it empty for long periods is not good for it (according to common wisdom).

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

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Sidney Stratton wrote:
Bort wrote:
Interesting charger but it would just hide this problem. I would personally use a regular charger at least occasionally so you can spot this problem on old cells. Aim for 0.33-0.5C charging on this charger so a very low charge rate doesn’t hide the problem.

Why would I use a cheap charger? And the whole purpose of having a charger measure IR and charge consequently is for hassle-free operation. Those economical chargers seldom do more than 1 amp which is too low for my cells and my patience. I mean charging 4 × 30Qs or VTC6s individually at 1 amp was taking me some 12 to 24 hours. And the trouble of monitoring and changing the cells. That is the whole purpose of having a 4 bay unit to quickly bring these up.
And as my collection grew, I didn’t want to spend time charging the various cells I used in the day so I got a second charger. Again, for simplicity and speed.


A 4 or 8 bay charger is not pricey these days.

Quote:
Are you implying a ⅓C charge rate (1 amp w/3000mAh) can heat a worn-out cell?

Oh yeah.

Quote:
Or the fact the charger changes the rate of charge if the cell heats up. But the latter I didn’t mention. Geez, I’ve been charging at 2 to 3 amps (auto selection) and if I was to see less than 1 amp, I’d check the IR.

If your cells are not overheating at 2-3 amp then it should not overheat either at 1A.

Quote:
I’m not trying to extend battery life. A cell is to be to my expectations and when they show fatigue, they’re replaced.

To each their own.

Quote:
BTW this is in the context of the 18650s, the 21700s, and the 26650s. My smaller cells auto-charge rate. I expected them to not last as long in cycles being less capacity. But my Sanyos (14500s) are doing fine after 2 years at about 2 recharges per week. In 2 more years will see if capacity is lost.

I get it you may. have the time and inclination to pamper your cells. My working lights have to be dependable and I don’t skim on the batteries. There is an underlying psychology of turning the light on/off from one peak to another, mentally conditioned to extend battery life. The introduction of rechargeable batteries with high capacity and no memory effect should alter this behaviour. I turn the light on and when temporarily not in need, lay or cover the face. I don’t play with the switch. If the light becomes warm, tone down the intensity. I work with gloves and 50ºC is acceptable. If the light gives a low battery signal, I replace it or pull out another light. Always have a backup.


If you have money to spend then you can push your cells as hard as you wish and replace when the time comes.
Though please recycle your old batteries.

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

Bort
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raccoon city wrote:

Lightbringer wrote:

Yeah, I’m kind of at a loss as to how a cell might need to be tortured’n‘abused to get that worn down.


Too many zeros.  ;)


The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

zoulas
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You have to ask yourself what is your goal. Is your goal to keep the $5 battery as long as possible? I have batteries >10 years old. You know what, I would not use these batteries in a light used to light a bathroom
to take a crap.

Is your goal to be able to have the freshest batteries possible, do what I do and replace them often.

If your goal is to learn how to use a DMM, then keep them for 10 years and test them every day and report back the voltage drops on a daily basis.

Personally, life is too precious to be spending time trying to get every penny possible out of a $5 investment.

This is $5 that can save you life one day. Pick another place to save some money. Like a cell phone or cable bill.

I have expressed my goals, your goals may be different and I totally respect that.

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zoulas wrote:
You have to ask yourself what is your goal. Is your goal to keep the $5 battery as long as possible? I have batteries >10 years old. You know what, I would not use these batteries in a light used to light a bathroom
to take a crap.

Is your goal to be able to have the freshest batteries possible, do what I do and replace them often.

If your goal is to learn how to use a DMM, then keep them for 10 years and test them every day and report back the voltage drops on a daily basis.

Personally, life is too precious to be spending time trying to get every penny possible out of a $5 investment.

This is $5 that can save you life one day. Pick another place to save some money. Like a cell phone or cable bill.


I use my almost 10 year old batteries regularly, no problems. In fact my oldest lithium battery is in my newest light.

Life is too precious to take care of batteries? Its knowledge and habit since long ago. And like many BLFers i have more than one battery. Lets say one has two dozen batteries. And replaces them at $7 a pop every 3 years. In 9 years that is $672 (initial, 3 year, 6 year, 9 year). And tax depending on where purchased. I spend more than $5 each, most are $7-10 each.
Some BLFers have dozens or hundreds of batteries, replacing them every 3 years is several thousand dollars in 9 years. Thats ridiculous.

And my cell phones last much longer than 3 years as well, my last phone is over 3 years old and has 96% battery life.

I want to know how you eat 80% of your batteries lives in 3 years, what are you doing to them?

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CRC
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Cells may be listed as $5, but dont forget about shipping.

To buy a single 18650 will cost me 36.48 Canadian.

At that price it better last forever.

Bort
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CRC wrote:
Cells may be listed as $5, but dont forget about shipping.

To buy a single 18650 will cost me 36.48 Canadian.

At that price it better last forever.

!https://i.imgur.com/CWa8SJJ.jpg!


Agreed!

I typically go for the highest capacity because i like runtime so i typically buy higher priced batteries. Some 21700s i am looking at are about $13 each plus shipping. Also being Canadian the exchange rate is about 1.25CAD per USD.
But lets go with this battery and stick to USD, if you buy 12 batteries plus shipping it will be about $7 each. So $84.5/dozen. As i mentioned earlier imagine one has a modest two dozen batteries in their collection. And replaces them every 3 years. $169 times 4 changes is $676 USD. Or $845 CAD Sick
This is more than my whole flashlight collection cost me.

I would prefer to keep my money by adopting some simple battery practices so i’m not throwing away lots of cash.

The Journal of Alternative Facts TM

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chops728
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From reading on another thread — people are having more trouble with newer cells —— I have plenty of cells that are over 5yrs old — most of the Good Name Brands (Panasonic- Sony -Samsung ) are as new — But like the OP stated it’s what you’re into ( I test my cells Capacity /4 wire resistance ) —- even with so called good cells and lights, It’s always best to have a Backup

CollectEverything
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Bort wrote:
zoulas wrote:
You have to ask yourself what is your goal. Is your goal to keep the $5 battery as long as possible? I have batteries >10 years old. You know what, I would not use these batteries in a light used to light a bathroom
to take a crap.

Is your goal to be able to have the freshest batteries possible, do what I do and replace them often.

If your goal is to learn how to use a DMM, then keep them for 10 years and test them every day and report back the voltage drops on a daily basis.

Personally, life is too precious to be spending time trying to get every penny possible out of a $5 investment.

This is $5 that can save you life one day. Pick another place to save some money. Like a cell phone or cable bill.


I use my almost 10 year old batteries regularly, no problems. In fact my oldest lithium battery is in my newest light.

Life is too precious to take care of batteries? Its knowledge and habit since long ago. And like many BLFers i have more than one battery. Lets say one has two dozen batteries. And replaces them at $7 a pop every 3 years. In 9 years that is $672 (initial, 3 year, 6 year, 9 year). And tax depending on where purchased. I spend more than $5 each, most are $7-10 each.
Some BLFers have dozens or hundreds of batteries, replacing them every 3 years is several thousand dollars in 9 years. Thats ridiculous.

And my cell phones last much longer than 3 years as well, my last phone is over 3 years old and has 96% battery life.

I want to know how you eat 80% of your batteries lives in 3 years, what are you doing to them?

Well, heat kills so I’d guess that some user’s batteries last longer depending on how they are used and what kind of lights they get used in. Put an 18650 in a D4V2 and use Turbo every chance you get and I bet it dies sooner than if you put it in something more conservative and use medium modes except when necessary. Plus, if you are a busy or absent-minded person you might not charge the batteries exactly when you should every time. You might miss a low-battery indicator or forget to check the voltage and then the flashlight sits for a week at about 3 volts with parasitic drain on top of it.

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Collection: TN42, TN40S, Catapult V6, SP36 BLF, sc700d, sc64c LE, D4V2 CuZn, D4V2 CuTi, D4V2 Al x2, KR4 Al x2
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Wishlist: Acebeam K75, Zebralight sc600w mk IV plus, Convoy M3-C
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