What is your cutoff for 18650 health?

MyUsernameTX

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I have a bunch of 18650's, a bunch of new 3400mah ones, a few salvage Samsung cells that are 3000mah, but also a ton of older Sanyo cells that were 2600mah design capacity

Doing a capacity test on a few, and some are 2500+ which is pretty good, but some that are 2300mah, and maybe some that are below, one is just 2000mah which makes me want to toss it. However, it holds a charge for years, internal resistance is low, so its still a good cell.

What is your cutoff? A 3400mah cell is $5, so is it even worth keeping these low capacity cells around? Just wondering your guys thoughts
 

vicv

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I have a bunch of 18650's, a bunch of new 3400mah ones, a few salvage Samsung cells that are 3000mah, but also a ton of older Sanyo cells that were 2600mah design capacity

Doing a capacity test on a few, and some are 2500+ which is pretty good, but some that are 2300mah, and maybe some that are below, one is just 2000mah which makes me want to toss it. However, it holds a charge for years, internal resistance is low, so its still a good cell.

What is your cutoff? A 3400mah cell is $5, so is it even worth keeping these low capacity cells around? Just wondering your guys thoughts
First off I would automatically throw away every 3400mah cell. If it is the Panasonic NCR cell. Besides that, I usually toss them when they're below 70% of original capacity. But remember when testing that most of these cells are made to be discharged to 2.5v but most testers only go to 3v so I usually add ~150mah to my test result
 

vicv

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Why would you throw away a 3400mah cell?
Because they were bad when they came out. Haven't gotten better. They're ok in a series configuration with a 3v led and buck driver. They have such high resistance that there's a large voltage drop under load. And all their extra capacity is down below 3.2 volts. Which is usually before the vf of the led so it's out of regulation. I would honestly take the 2600mah cell any day over one of them.
Look at how they compare to a 30q. The 3400mah doesn't have more capacity until below 3v

IMG_0177.png
 

MyUsernameTX

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Because they were bad when they came out. Haven't gotten better. They're ok in a series configuration with a 3v led and buck driver. They have such high resistance that there's a large voltage drop under load. And all their extra capacity is down below 3.2 volts. Which is usually before the vf of the led so it's out of regulation. I would honestly take the 2600mah cell any day over one of them.

My experience with testing them has been completely opposite, maybe you got a bad batch?
 

vicv

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My experience with testing them has been completely opposite, maybe you got a bad batch?
I got an AW cell. It dropped to 3.75v under a 1A load when fully charged and kept dropping quite quickly. It's well know they are a low performer. But the test I showed definitely proves it. It's from HJKs site
 

vicv

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Oh. Ya the 3500mah is a good cell. I only meant the 3400. I know they were popular when they came out, but I think that's only because no one knew any better. And they had a big number. But I noticed a big drop in output used with incandescent and the first xmls as they had a pretty high vf.
I'm not against Panasonic. I like their ncrb 18500 and your 3500mah cells, even though I do prefer the Samsung 35E cell.
Sorry to derail though. I just really dislike the 3400mah cell and feel it's my duty to get people to toss them and get something better! Lol. As for throwing stuff out, I still have some 1300mah 18650s. They still work great but they do just sit in a drawer at storage charge. Capacity isn't a big deal to me.
 

bigburly912

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Oh. Ya the 3500mah is a good cell. I only meant the 3400. I know they were popular when they came out, but I think that's only because no one knew any better. And they had a big number. But I noticed a big drop in output used with incandescent and the first xmls as they had a pretty high vf.
I'm not against Panasonic. I like their ncrb 18500 and your 3500mah cells, even though I do prefer the Samsung 35E cell.
Sorry to derail though. I just really dislike the 3400mah cell and feel it's my duty to get people to toss them and get something better! Lol. As for throwing stuff out, I still have some 1300mah 18650s. They still work great but they do just sit in a drawer at storage charge. Capacity isn't a big deal to me.
You know there's tons of different 3400mah batteries right? Just one bad cell doesn't mean every single 3400 that came out is bad. I have Some from liionwholesale from when they first came out and they still run great and test out good.
 

vicv

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You know there's tons of different 3400mah batteries right? Just one bad cell doesn't mean every single 3400 that came out is bad. I have Some from liionwholesale from when they first came out and they still run great and test out good.
Maybe you didn't see the test I showed? Check his site. Compare every single 3400mah cell to any other good one and look at the results. Are they an ok cell and you've had good luck? Probably. Doesn't mean all the rest aren't better.

Edit. I went back to his site and compared the AW cell(Panasonic ncr18650b) against 15 other 3400 mA hour 18 650 cell. They all have the exact same discharge graph. Most of the others performed worse, probably due to a lower quality protection circuit. But they are all definitely the same cell. So yes. Every 3400mah cell is the ncr18650b. And they perform worse than every other 3000+ sell from any of the good manufacturers. Like Panasonic, Sony, LG, and Samsung. For the time they came out, they were great. If you put them in a circuit with a lot of voltage overhead and a buck driver. And only if that drivers LVP would bring them down all the way to 2.5 V each.
 
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MyUsernameTX

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Just found a few that were just 1000mah! Out they go for sure.

All the purple Samsung ones that are good are reporting around 3000mah with a 1a charge and discharge. A few of them won't hold a charge over a few weeks, toss those? These are from a failed M18 9AH battery pack
 

letschat7

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I run some very old Pila batteries that have very little capacity in them. Running a EO-4 bulb drains them fast but with LED I get enough runtime to not bother yet.
 

vicv

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Just found a few that were just 1000mah! Out they go for sure.

All the purple Samsung ones that are good are reporting around 3000mah with a 1a charge and discharge. A few of them won't hold a charge over a few weeks, toss those? These are from a failed M18 9AH battery pack
Definitely if they can't hold a charge toss them. Lithium ion should have no self discharge
 

orbital

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+

I'v had a couple cells over the years loose their mojo,
but just the other day I had an eye opener.

Was charging four Panasonic 18650 that only had maybe 10 recharges on them,,, one looked like it was done but didn't say 100% as it should (acted as if there was no battery in charger)
Figure I'd just take it out and it was almost too hot to touch!!
didn't know when the charger said 'nope' to that cell, but the fact it did really showed the importance of >>> Charger Cutoff*

Took the voltage of that cell and watched it drop & drop (that cell didn't stay in my house)
I retested that 'bay' and charged a 21700,, worked fine.



*and other safety parameters
 

MyUsernameTX

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Very frustrating, I have some protected 18650's I got a long time ago, most probably based on the 3400mah Panasonics

The protection circuits are so sensitive that they cut off right as you get to 4.2v, and right when you get to whatever the lower limit is. This makes capacity testing them on my Opus C3100 impossible! Gah! Even my Nitecore USM4 can't give me how much capacity it charged it to, as it turns off when it gets full
 

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