Has Anyone Else Noticed...
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Yup. I have some VTC5s that were made in January of 2014, which I got later that year. They're still in service in my nightstand / breakfast vape. I've occasionally though about retiring them, and but as long as they perform adequately, I'll keep using them.If it ain't broke...
I still have 14 genuine AW 18490 batteries that I use in a Provari. I'm not sure how old they are.
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+1 for the Miboxer C4-12 version 2. I love mine. I purchased after researching for a couple of weeks.Did you try IMR? They usually carry a decent selection of chargers. My current favorite charger is the Miboxer C4-12 version 2 charger. It charges all the batteries I use (18650, 26650, 20700 and 21700). Bought mine on 2019-08-06 from Aliexpress.
IIRC Amazon carries MiBoxer chargers but you need to be very mindful of which one (model/version) because some of their chargers look very similar. I have also had very good luck with my Nitecore chargers. I seem to collect chargers.
I know some folks prefer the automatic trickle charge of most of the other perfectly good chargers but I like the way this one measures the internal resistance of the battery and bases the charge on that when I just leave it on auto mode. It also reduces the charge rate automatically to a very low trickle when topping off the last bit of the charge. You can see what its doing while its doing it.
Most of the batteries we vapers like are capable of much higher charging rates and at the molecular level I think its good to tickle the charge with higher rates, it keeps the batteries fresher longer. Of course there are varied philosophies on that subject. I've done deep dives but I can't remember half of it anymore.
I also agree with the if it ain't broke don't fix it philosophy. But sometimes I just like the latest cool kid toys.
I still have 14 genuine AW 18490 batteries that I use in a Provari. I'm not sure how old they are.
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AW's never die, they just fade away.
Good luck.
p.s. I slow charge everything, mostly.
AW's never die, they just fade away.
Good luck.
p.s. I slow charge everything, mostly.
I have a Nitecore. I always use the "low" charge setting, unless I forget.
Primarily rely on a pair of OPUS chargers which bring to full charge and discharge to 4.15v. I'll use various Xtars to top charge on occasion for a mech or to check if a batt's full at seriously under a 4.2v (these go to lights). Usually rest voltage (assuming over 4.15v) is adequate for most of my mods. Keep a batch of relatively pristine 30A for high pwr builds which usually rotate out to dual VV-VW's as they fail to top at 4.2, a strategy that's kept me safe so far. Don't use anything under 20A.
It's really difficult to keep track of how effective using rest volt vs. top charging is anymore. Increasingly batt's fail to reach 4.2v after rather a few cycles comp to just a few years back. Also cutoffs have become inconsistent. AW's were always great that way. Now you have to exercise caution as premium cells become scarce. Thank goodness for @Mooch.
Good luck.
It's really difficult to keep track of how effective using rest volt vs. top charging is anymore. Increasingly batt's fail to reach 4.2v after rather a few cycles comp to just a few years back. Also cutoffs have become inconsistent. AW's were always great that way. Now you have to exercise caution as premium cells become scarce. Thank goodness for @Mooch.
Good luck.
Stick a voltmeter on them during toward the end of charging. I bet the do reach 4.2V and are held there for some time by the charger during the constant voltage phase until the current they're willing to accept at 4.2V drops below the threshold set in the charger and it cuts off. Then they start dropping back some, but this doesn't happen instantly.
I've noticed this too with newer batteries. In fact, my ancient VTC5s seem to be the champs at holding closest to 4.2V, generally not dropping below 4.18 or even 4.19 when charging is done.
Interestingly enough, the opposite happens if you discharge them down to a low voltage. I've run quite a few 0.2C discharge tests down to 2.8V, and I find the worse shape the cell is in, the more it rebounds from there when I stop pulling current.
For me on the top side, I found both the 5's and 5A's to be very consistent. About the best of the many alt's I've tried. So early on I went bulk on the latter (but down to my last few). With that and other buys the discharge tests became less critical.
While hoping for the best, I started staging for the ban early on to be sure. And all your work (and of others) is greatly appreciated. Sadly I don't have the time or endurance these days to do the testing I used to. Struggling now months to sort out a photo renumbering problem on the old iPhone, and attendant temp files. So no posting. At least I'm keeping my small posse in builds and juice as the party rolls up round here. That's priority right now with all that's goin on.
Good luck Ross.
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I have no one except myself to keep in builds and juice, and my builds last a very long time, so vaping has become a very low effort thing for me.
Now I did mean to do another round of testing on all the cells that are part of my cell storage experiment this summer. Eight of them are VTC5As that have now been in storage at different temperatures for 2 years, and eight more are P26As that have been in storage for one year. Unfortunately, I'm stuck up here in PA, and all that stuff is down in FL.
Spoiler: The results from the tests one year ago (only the VTC5As) indicate that cells in storage really do age less at lower temperatures (i.e. fridge vs. room temperature) but there's not much to be gained by going all the way to freezer temps.
“Fake” is a word that is much more commonly known though and, IMO, makes the post easier to understand. Some might not know what “counterfeit” really means. Also, those whose first language is not English (a huge part of our community) may have never even heard of “counterfeit”. “Fake” they know though.
This is only due to the battery and how everything flows inside. Chargers don’t adjust the current level at the end. You can see this same behavior using a basic constant-current power supply instead of a charger.
As the battery charges up there is less of a difference in voltage between the battery and the charger’s 4.2V setting. This makes it harder for the charger to force current to flow.
Also, as the battery fills up it becomes tougher and tougher for ions to find a nook or cranny to settle into and that causes a false voltage rise as the ions pile up in certain locations inside.
This voltage rise makes the battery reach 4.2V early and makes it hard for the charger to push anything in to the battery since they appear to (almost) be the same voltage.
(Edited to correct an error I made)
This is expected and is the opposite of what happens during charging (where there is <100mA flowing). They’re both caused by the internal resistance of the cell. Ohm’s Law says that Current x Resistance = Voltage. So if we have higher current at the end of a discharge then there was more voltage sag and there will be more bounce back.
The worse shape the cell is in the higher the internal resistance is and the bigger the voltage jump will be when the discharge current flow stops.
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I always wondered about that. My XTAR takes a longish time to get from 4.0 to 4.2, and then it sits at 4.2 for a while before it goes to green. Makes a bit of sense now. These days I take them out around 4.1 if I'm there and paying attention.
When I got my Asmodus tester and ran the capacity test I noticed that the battery ran down from 4.2 to 4.0 really fast. I figured that meant there wasn't much there above 4.2, to put it in non-scientific language.
OK, but the voltage drop after charging is generally no more than 50 mV (e.g. from 4.20 down to 4.15) while the "bounce back" I've observed after discharging down to 2.8V at 0.2C is has always been hundreds of mV. With cells that are "new" (have not been cycled except in testing), I'm generally seeing ~200-300 mV, and cells that have seen a lot of use can be double that.
It does indeed take some time for them to bounce back, and to be fair, I've recorded my bounce-back data without keeping track of how much time passed since the discharge stopped. Next time I test the cells in my long-term storage experiment, I will try to get some plots vs. time.
That said, I have a hard time with attributing something that takes many minutes to an hour or longer to "Internal resistance".
Another test I might do at some point just for laughs is to see how much more energy they will produce without recharging after they've been given a few hours to bounce-back. I don't think it will be a whole lot, but it will clearly be some...
The larger bounce back after a discharge is because of the large difference in the amount of current that is flowing. At the end of charging only 50mA to perhaps 100mA is going into the cell. At the end of the discharge you have a lot more current flowing so the internal resistance causes more voltage sag (Ohm’s Law) and that results in a bigger immediate bounce back. Then you have the much slower settling of the ion distribution to get the cell to its true resting voltage.
You’re right, I made an error. My apologies for any the confusion that caused. In my rush I mixed things together I should not have.
The settling to the resting voltage has nothing to do with the regular DC resistance of the materials or the “polarization resistance” (ion flow needing to shift around and set up for a different current flow direction) that causes a voltage change when the current starts or changes directions.
The process for ions settling into the anode or cathode material is called “intercalation” and can take a long time to finish. The larger the current flow was before stopping the longer it takes to settle. It happens faster after charging since the current flow at the end of charging is pretty small.
A large part of the settling happens in a few minutes but for some applications you need to wait for a very long time before reading the cell’s voltage to be able accurately determine how much charge is left in the cell. This is typically for LiFePO4 and other cells with very flat discharge curves. Just a small difference in the voltage can equal a large difference in the amount of charge left in the cell. Millivolts make a difference.
For our “standard” Li-Ion cells it’s less of a concern but millivolts can still matter when around the mid-point of the charge, near 3.6V (resting voltage). It all depends on whether you need to know how full a cell is to one percent or whether just 1/4, 1/2, 3/4, FULL is enough.
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