18650s going dead just sitting for 2 days?

[Robby123]

I’m speaking of some efest 18650s I’ve had for about 3 months. Swapped back and forth with another pair every other day. Now I purchased a 3rd set of batteries (holm life) so they get used every third day. Charging on a nitecore Smart charger. Some times on the rotation on the second day they are dead when they should be charged just sitting in my vape bag in individual plastic battery tubes. Only thing would be me forgetting to charge them. But it’s happened twice. Is this normal? I’m thinking not but after they charge they work fine just won’t hold the charge. Trash or am I doing something wrong?

 

[PoppaVic]

Not sure which cells have which issue, given that paragraph.

 

[Robby123]

I’m sorry it’s a pair of 18650 efest.

 

[PoppaVic]

Efest, for all intents and vaping purposes, are trash.

Using an external charger, even at 0.5a, I can charge any set of cells in under 4 hours - and get a solid 4 to 8 vaping out of them.

Charged cells sit in their boxes on the counter, and any one of them I snag Just Works. I rotate my sets of 25R's and VTC5a's and they will sometimes sit unused for days. Even brand new cells come with at least a 3v charge and can be used within several hours. ...and I have no idea how long they've sat in their little cardboard boxes in a case or on a shelf.

I'd never buy efest - even for a flashlight. I went down that path years ago.

 

[inspects]

efect are rewrapped junk batteries from other manufacturers, they don't actually make them.

I too learned the efest lesson many moons ago.....their junk.

 

[Robby123]

Ok thanks guys time to swap out.

 

[jwill]

If it is the Nitecore without a display I have experienced sometimes it doesnt read the battery when inserted so it doesnt actually charge it. When I use that one, sometimes spinning the battery a little makes it realize something is there. May want to verify it is actually starting to charge when inserted. efest batteries are garbage so cant rule that out either.

 

[Fudgey Finger]

I'm no efest fan (I only own vtc5a's and Ijoy 26650's) but I was under the impression that efest has come a long way and is no longer the company they were a few years ago. They accurately rate their cells now.

Just because a battery is a rewrap doesn't automatically make it junk.

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[Robby123]

My nitecore has a screen. I always watch it to make sure it starts charging and to see what the base voltage of the battery is when it starts charging.

 

[jwill]

Sounds like memory effect.

 

[Fudgey Finger]

Lithium ion cells don't have memory. This would have been true of older cell technologies but not li-ion.

Sounds like memory effect.

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[jwill]

Lithium ion cells don't have memory. This would have been true of older cell technologies but not li-ion.

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Didn't say it was. Said it sounded like. Huge difference.

 

[Ralph_K]

Efest, for all intents and vaping purposes, are trash.

Using an external charger, even at 0.5a, I can charge any set of cells in under 4 hours - and get a solid 4 to 8 vaping out of them.

Charged cells sit in their boxes on the counter, and any one of them I snag Just Works. I rotate my sets of 25R's and VTC5a's and they will sometimes sit unused for days. Even brand new cells come with at least a 3v charge and can be used within several hours. ...and I have no idea how long they've sat in their little cardboard boxes in a case or on a shelf.

I'd never buy efest - even for a flashlight. I went down that path years ago.

The Nitecore D4 I have charges at 375ma with 4 batteries and 750ma with 2 batteries. Takes 4hrs to charge 2 3000mah batteries. If you can charge a battery in 4 hrs at .5A must be a 2000 mah battery.

 

[PoppaVic]

I'd say your math isn't bad, otoh don't forget the charge-time also relates to the amount you drained them.

 

[Fudgey Finger]

.

 

[Fudgey Finger]

Didn't say it was. Said it sounded like. Huge difference.

Yeah, ok buddy.

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[jwill]

Yeah, ok buddy.

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Not being rude or trying to start an argument. Just saying what it sounds like. Im also pretty sure Lexus or some other Hybrid car manufacture found that some chemistries of lithium batteries do experience memory effect.

 

[dr_rox]

Not being rude or trying to start an argument. Just saying what it sounds like. Im also pretty sure Lexus or some other Hybrid car manufacture found that some chemistries of lithium batteries do experience memory effect.

Nope. Not with the chemistries we use. LiFe - the 3 volt cell - may have issues.

Memory effect is not demonstrated by having a dead cell.
Only an undercapacity cell.
Why do you think it is called memory effect??

Simply.....
A cell is partly discharged then recharged.
It 'remembers' this and and when it is required to go full cycle, it responds 'no... don't remember how to to do this'.
Hence memory effect.

Battery types that suffer from memory effect should be drained fully before being recharged to prevent this.

 

[jwill]

Nope. Not with the chemistries we use. LiFe - the 3 volt cell - may have issues.

Memory effect is not demonstrated by having a dead cell.
Only an undercapacity cell.
Why do you think it is called memory effect??

Simply.....
A cell is partly discharged then recharged.
It 'remembers' this and and when it is required to go full cycle, it responds 'no... don't remember how to to do this'.
Hence memory effect.

Battery types that suffer from memory effect should be drained fully before being recharged to prevent this.

I went and dug up the articles. It wasn't Lexus, it was Toyota.

http://pocketnow.com/2013/05/03/li-ion-batteries-memory-effect

https://phys.org/news/2013-04-memory-effect-lithium-ion-batteries.html

http://adsabs.harvard.edu/abs/2013NatMa..12..569S


This was a big deal when it was discovered.

 

[dr_rox]

I went and dug up the articles. It wasn't Lexus, it was Toyota.
http://pocketnow.com/2013/05/03/li-ion-batteries-memory-effect
https://phys.org/news/2013-04-memory-effect-lithium-ion-batteries.html
http://adsabs.harvard.edu/abs/2013NatMa..12..569S
This was a big deal when it was discovered.

Like I said.... nope.
Those are LiFe batteries.... 3 volt cells.
We do not use those.
We use LiMn or LiNiMnCo .
Do you understand???


I have flashlights that use 3V CR123a Lithium cells, non-rechargeable.
There are equivalent LiFe rechargeables, LR123, but they suck. I have gone thru several sets.
They have memory issues. Flashlights sit in a drawer until they are needed, causing this.
I was unable to use the LiMn variety 17340 since it would blow the led drivers out.
There was no current limiting of the higher voltage.

I am still using LiMnxxxxx batteries that are 5+ years old, in flashlights, drills, saws, and vape gear, and do not EVER encounter memory effect. I have used 100's of NiCads and NiMH batteries as a photog, and they sucked. Even with constant use and using a battery rejuvenator that was supposed to fix the xtallizing effects of the electrolyte, they still did now work for very long.

All Li batteries are not created equal.
http://batteryuniversity.com/learn/article/types_of_lithium_ion