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So, how long should an 18650 last?

Long term obviously. Difference in capacity and wattage will greatly vary short term battery life.

However assuming daily use and no damage to the cells how long before capacity starts to drop off rapidly?

Obviously people vape at different rates so I'll give you an estimate of my usage.
I have 2 cells, one a vapcell and the other a molicell. [tangent] A note on the vapcells is to avoid the ones from amazon. I ordered two along with my mod, one came undervolted, the replacement came undervolted, the third came at the correct voltage. A 50% success rate isn't exactly good, unless I just got a bad batch. [/tangent] The molicell is because I got one while waiting for the replacement vapcell, I just kept it in my mod.

This adds up to 5.1Ah, I would go through about 3/4 to a full charge (sometimes more, sometimes less) in a day. I usually top the cells up at about 50% charge using a powerbank (there's less that can go wrong when using a powerbank as it's going to give pure DC, no noise and no voltage dips or spikes), I vape at 75W 0.18Ohms (roughly 3.7V).

Its been about 5 months. I think the cells are draining faster. They seemed to drain really rapidly today however the powerbank (10Ah) read 0% and wasn't at 100% when I picked it up. I don't remember exactly what it read but it's got a 7 segment display and I might have read it upside down (eg reading 18 as 81). However they seemed to drain more quickly over the past week.
I went ahead and ordered two new molicells from a more reputable company (Fogstar) anyway. After all, backup cells are good.

Anyway is 5-6 months an expected lifetime before they start losing capacity or was that quick?
 

nadalama

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Sounds quick to me, but you vape at a higher wattage and with fewer batteries than I do. My lower-wattage usage (35 to 55W depending on the device) is spread over many devices with many different batteries, so they each won't be charged a comparable number of times, in any defined span of time, as yours.

Perhaps I read you wrong, but it sounds like you are saying you vape at 75W on a single-18650 mod. If that's the case, you're vaping at almost the ceiling of what a single battery can do, day after day, and it seems to me, that would contribute to quicker mortality. I don't know of a single-18650 regulated mod that is rated for more than 90W, and most of them are rated closer to 80W.
 

~Don~

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Cycle life on the data sheet explains this.

Cycle is down to 2.5v

Batteries rarely ever hit true 4.2v rested, more like 4.17-4.19v new.

7953f8156b745764b85907df94782be1.jpg


This is the Samsung 30Q for example.

It has a 250 cycle life.

It will maintain 60% at max discharge at 250 cycles.

Now most mods won’t discharge a battery down to 2.5v to full cycle… mostly down to 3.2v or 3.0v (rebound) but will sag draw them below 2.5v depending on wattage, either case the rebound or charge state is the reference for cycle.

Let’s say you plop your battery into the charger bay and initial read is 3.4v

That’s 0.8v of usage of 1.7v theoretical voltage or roughly a half cycle.

Which the 250 life cycles can be approximated double… but for shits and giggles we will drop it to 450…

450 charges is the serviceable life of the 30Q…

Let’s say you charge said battery once a day…

Well you basically have 450 days of serviceable life…

But, the later in said cycle life, you will be putting said battery on the charger more often due to degradation… or loss of mAh

This is at max amp draw, ymmv based upon your wattage drain (which is not what(watt! Lol) shown on the screen of your mod)

Tl;dr

1 year on batteries serviceable capacity used at its max capability.


Sent from my iPhone using Tapatalk
 

~Don~

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Forgot to add… this is a single battery, I am sure that was inferred

If you have let’s say 5 of the same batteries and cycle them also, you can extend the service life of them all, but not 5 times as long


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VapeOn1960

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I have 4 18650 batteries and an external charger (Nitecore Q1) The charger is a simple 2 bay with no screen (just LEDs) My two older batteries are MXJO and have been charged many times (used in single battery mods). At first, I charged one at a time using the left bay (didn't know there is a difference... left charges at 2A, right bay at 1A) After I learned there was a difference, I started using the right bay (slower charge which I assume is better) I rotate mods during the day so not heavy use on these batteries (and at fairly low watts) Recently, they discharge faster (seems like they discharge slower from full to half (just going by what the mod shows) then discharge very quickly after that (getting worse as the months go by) Just recently, one of them (I think I used it more often) after sitting all night on the charger, does not show quite full charge in my mod... it is dying for sure. The other one doesn't seem as bad. These are not a great brand but never got pushed (low wattage mostly) so worked fine for my use. My other batteries are Sony VCT5a, are not as old and are a "married" pair. I use them in a dual battery mod (and still relatively low watts for a dual battery mod) When charged at the same time, they charge at 1A each. I often charge them before my mod shows all the way low (I've heard it's better to charge when they get down to 20 %) I only use this mod in rotation with other mods (including internal battery) The batteries are 1 year old and doing great. Of course, they are also a better brand. For the most part, none of the batteries have been exposed to extreme temps (both low/high) These mods stay at home (use the internal battery mods for carry around)
 
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Vape Fan

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Isn't there a [point] by which charging a [partially] charged battery. is not considered a cycle?
 
Forgot to add… this is a single battery, I am sure that was inferred
Two cells (18650s) in the mod. Max wattage is 200W. I probably worded things badly but there are two different cells in the mod. That's probably where the confusion came from.
This might be bad in a mech, but I can't see it being a huge problem in a mod which balances the cells and monitors them, so long as both cells have similar specs and are used within them.

Isn't there a [point] by which charging a [partially] charged battery. is not considered a cycle?
Indeed there is, charging a cell that hasn't been cycled past a certain point lengthens its life significantly. Cordless tool manufacturers have known this forever and now that the batteries for them are pretty much protected with DRM they make sure the cells discharge to the maximum safe amount.
It'll never say in your manual "In practice you should recharge when you hit about 50%" which most older manuals (for things which don't rely on a razor and blades model) would do, or even have a setting on the tool battery (they all have the little LED indicators that are usually operated by a push-button) where three presses will cause the battery tool to turn off at the optimal percentage, three presses turns it back on.

I think electric car manufacturers at least suggest charging at the end of the day rather than running the battery dry.
 

~Don~

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Two cells (18650s) in the mod. Max wattage is 200W. I probably worded things badly but there are two different cells in the mod. That's probably where the confusion came from.
This might be bad in a mech, but I can't see it being a huge problem in a mod which balances the cells and monitors them, so long as both cells have similar specs and are used within them.


Indeed there is, charging a cell that hasn't been cycled past a certain point lengthens its life significantly. Cordless tool manufacturers have known this forever and now that the batteries for them are pretty much protected with DRM they make sure the cells discharge to the maximum safe amount.
It'll never say in your manual "In practice you should recharge when you hit about 50%" which most older manuals (for things which don't rely on a razor and blades model) would do, or even have a setting on the tool battery (they all have the little LED indicators that are usually operated by a push-button) where three presses will cause the battery tool to turn off at the optimal percentage, three presses turns it back on.

I think electric car manufacturers at least suggest charging at the end of the day rather than running the battery dry.

I understood everything you said, but my quoted response I think was misunderstood.

Cycle life in my first response was based off a single cell added the second response to clarify.

Anyway watts law on a 200w mod is simple to perform.

200/2=100

100/3.2= 31.25

31.25/.85 = 36.75a draw per battery

Let’s say you vape at 200w, regulated doesn’t care if they’re the same cell.

But unless you’re using a 35a cell, which there isn’t any in 18650, you’re going to stress them and they for sure will wear and drain fast and I’d be surprised if at 85-90% charges state at 200w the mod wouldn’t fault out and just not fire, or fire at the max it senses the batteries can provide.

I find battery cells inexpensive and rotate out of the working set often, mostly due to low ohm mech use and only 21700 cells…

I probably have 50-60 Samsung 30Ts I won’t use in my mechs anymore due to the abusive manner in which I used them… but are perfectly fine in let’s say my 21700 Boro mod at 13w


Sent from my iPhone using Tapatalk
 
I understood everything you said, but my quoted response I think was misunderstood.

Cycle life in my first response was based off a single cell added the second response to clarify.

Anyway watts law on a 200w mod is simple to perform.

200/2=100

100/3.2= 31.25

31.25/.85 = 36.75a draw per battery

Let’s say you vape at 200w, regulated doesn’t care if they’re the same cell.

But unless you’re using a 35a cell, which there isn’t any in 18650, you’re going to stress them and they for sure will wear and drain fast and I’d be surprised if at 85-90% charges state at 200w the mod wouldn’t fault out and just not fire, or fire at the max it senses the batteries can provide.

I find battery cells inexpensive and rotate out of the working set often, mostly due to low ohm mech use and only 21700 cells…

I probably have 50-60 Samsung 30Ts I won’t use in my mechs anymore due to the abusive manner in which I used them… but are perfectly fine in let’s say my 21700 Boro mod at 13w


Sent from my iPhone using Tapatalk
Oh right. Single battery, two cells. Gotcha. There's a lot of mix-up between a cell and a battery with pretty much everyone even people with an electronics background will call a single cell a battery sometimes. I assume this is a cultural holdover because older tech required more than a few volts due to thermionic tech rather than silicon/germanium tech, we still have higher voltage batteries such as 9V being the most common but most are single cells now.

I don't vape at 200W that would cook cotton in one or two inhales. I vape at 75W. Which is a 20.2 amp draw on both cells, 10.1A on each cell, well within the 20 and 25A claims on said cells.
I think I vaped at 200W once with them for one inhale. It wasn't comfortable.
 

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