Battery Question - how long do they stay charged when unused

[chellie]

I have decided to keep one of my mods with the battery removed in a spare purse. I had the bright idea that I'd keep 2 batteries charged in a plastic case. This way if I switch purses, I do not have to worry about forgetting my mod and, if I do, I will have a spare one.


So --- approximately how long will the batteries (21700) stay charged without being used?

 

[Lowjumper]

I have decided to keep one of my mods with the battery removed in a spare purse. I had the bright idea that I'd keep 2 batteries charged in a plastic case. This way if I switch purses, I do not have to worry about forgetting my mod and, if I do, I will have a spare one.


So --- approximately how long will the batteries (21700) stay charged without being used?

They say to check the state of charge once a year so a very long time

 

[HigherStateD]

You should be fine season to season, as pointed out above. The thing to remember, however, is that batteries don't like being stored, and also prefer to be at nominal (3.7) voltage if storage is necessary. As batteries age continuously, you'd be better served by switching them out with the ones you use periodically.

 

[BigPappa]

For long term storage, you should only charge your batteries to about 40%, then check every 6 months - 1 year to bring them back to 40%.

As mentioned, rotating them is probably a better option though.

 

[Rossum]

So --- approximately how long will the batteries (21700) stay charged without being used?

Depends what you mean by "stay charged". The top 5-10% of charge come off relatively quickly. After that, the rate of self-discharge will decline. Its also hard on batteries to sit around "fully charged". They will age more quickly if you leave them in that condition, and especially if you top them off regularly.

If I were going to keep a spare set, "ready to use" but not expecting to use them, I'd probably charge them to somewhere between 4.0 and 4.1V rather than the full 4.2V. This avoids the worst of the accelerated aging at full charge while leaving you most of the capacity. If they're reasonably fresh, I'd expect them to lose relatively little from there and be usable a year later, but I'd try to remember to check their voltage every six months.

 

[Falconeer]

I can only speak from my own experience. I own and use 7 iStick 30ws which I keep charged, but when I go away I only take two with me.

Any time I have come back and took one which had been left at home, out of storage, it worked for the usual time a battery would have.

Maybe this varies with whichever mod or battery you use or the climate in which you live ....

 

[HigherStateD]

I can only speak from my own experience. I own and use 7 iStick 30ws which I keep charged, but when I go awayI only take two with me.

Any time I have come back and took one which had been left at home, out of storage, it worked for the usual time a battery would have.

Maybe this varies with whichever mod or battery you use or the climate in which you live ....

It's more to do with duration of storage, as well as any passive drain from a chip. These discussions are usually academic, as we are discussing milliamps of draw on cells that hold multiple Amp hours. If you were to leave one sit for say, a year, and had some deterministic way of measuring the charge, it would be noticable. If I discharge one of my cells, hard, say, down to 2.8v chain vaping on a 0.16ohm coil, then let it sit over night, the voltage recovers back to over 3v. If I then charge it to 4.2, and let it sit over night, it recovers to 4.16v. if I were to discharge and recharge at slower rates, the "elasticity" wouldn't be as noticeable. If I then let that cell sit for, say a month or two, it may loose anouter hundredth of a volt or so, but that really doesn't equate to any noticable vape time, at least over a wattage threshold, esp because the above nominal voltage decreases significantly faster than that at nominal.

 

[Falconeer]

It was late at night when I posted - I missed out saying "when I go away to Spain for six months at a time, I only take two with me etc etc."

The first time I did this and came back I was surprised to find that any iStick I took out of storage still seemed to have the normal charge in it and lasted a full day as normal.

I'm sure there are scientific, chemical or something explanations for this but I don't do detail, so can only report my own repeated experience over four years.

 

[DaveP]

I generally keep my cells at full charge and rotate them. I ran across a shoe box in my closet that had some older hardware and several 18650's in storage cases in the box. When I put them on the charger all of them were in the 3.9v range after an extended rest for a year or more in the closet.

Internal resistance rises with use over time and can cause cells to self discharge more rapidly. Newer cells should hold a charge for a long time.

 

[Georgia Boy]

I generally keep my cells at full charge and rotate them. I ran across a shoe box in my closet that had some older hardware and several 18650's in storage cases in the box. When I put them on the charger all of them were in the 3.9v range after an extended rest for a year or more in the closet.

Internal resistance rises with use over time and can cause cells to self discharge more rapidly. Newer cells should hold a charge for a long time.

Completely agree Rotate, Rotate, Rotate

 

[Pigs]

I recently checked 2 Samsung 25Rs that I keep in an emergency stash of hardware at work. They were new batteries that I fully charged and then left in a drawer unopened for about 3 years. Both tested at about 4V.

 

[chellie]

Wow --that is all good to know. I rotate my batteries and I keep matched pairs. I am also a bit over-the-top and my battery cases are labeled --example 2 cases of 2 batteries are Aegis X, another 2 sets for Legend etc. I do that with the 3 --- 2 battery mods I use the most. For the single batteries, I do not.

I happen to have 2 Jackaroos. For work, I am in the tech field I dress kind of "rugged" and I wear a purse cross-body. In my fun time, I use something else. I am pretty organized and have an insert in the purse that I just move purse to purse plus I usually have my mod in hand but I did forget it once.

In any of my spare areas I have a tank, usually an rba , all wicked or an emergency disposable tank so I was thinking of leaving the jackaroo in that purse and keeping 1 battery in a holder in my "fun" purse --- and now I will.