Longevity - Higher capacity LiIo's vs Lower capacity LiIo's

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Zebretta
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Longevity - Higher capacity LiIo's vs Lower capacity LiIo's

I’m still trying to get up to speed on all this excellent battery tech and was wondering which (if either) tends to last for more cycles….high capacity batteries or lower capacity batteries. Or if that makes no difference.

For example what if we had two 26650 batteries from the same manufacturer, built the same day, same chemistry, used identically for their lifespan, but one 2500mAh and one 5200mAh.

Is there any reason one would tend to last longer assuming both treated identically? Isn’t there just basically ribbon inside and the longer the ribbon, the higher the capacity?
If true, then it seems that maybe the only thing that would make either of these batteries last longer than the other is the way it is charges, discharged and stored? I also know high heat is not good for batteries so lets assume they are never stored in a hot place for example.

The reason I ask is that I’m still in the process of building my bank of batteries and sometimes I can’t decide if I should spend the extra money on more capacity or just buy more lower capacity batteries. For example, 2500mAh batteries instead of 3500mAh batteries. My batteries aren’t going to see constant use. Actually somewhat sparse use so most of their life will probably be sitting in my battery apartment.

Thanks again. What a fascinating forum Smile

bella-headlight
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I buy cells based on what lights they are going to be used in & what draw will be put on them by that light & not what their capacity is.
High drain lights need cells capable of supplying high amps.
Low drain lights do not really matter so much as most cells will run them fine such as the ubiquitous Panny B.
You now have cells like GA“s that are both high capacity & high drain & cells are cheap so I am not really interested in their longevity.
I am turning more towards 30Q“s & GA“s as between those 2 cells you are pretty much covered.
Add in some Panny B“s & you are pretty much covered.

Ian

Zebretta
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I’m not sure there’s any useful information readily available on this.

The point of this thread has nothing to do with capacity per se related to use or drain / load etc.

I sometimes buy batteries just because. A good sale. “Might” have a use for them etc.
I just bought a bunch of NiZn cells because they work so well for me and because I read they have very long shelf lives.
But I also buy certain things for “future use”…with the possibility that it may not be available at a later time.

For example, I live where Hurricanes are possible, so I buy things in preparation for Hurricanes…even though we sometimes go a decade without one hitting.
But waiting until a major hurricane is one day out is too late. Prepping in a sense.

So with that in mind, if 2200mAh 18650’s were scientifically proven to last longer on the shelf than 3400mAh 18650’s (for whatever reason), then I would be wiser to stock up on 2200mAh 18650’s for shelf life purposes.

My WAG is that it makes no difference but that said, I’m not sure anyone actually knows the real answer to this question.
But if the capacity is increased simply by adding more of the same LiIo ribbon inside, then the capacity would have no effect on shelf life as I see it.
Just wanting confirmation basically.

Angler
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Maybe HKJ will chime in here.

I can’t give you a scientific answer, but I don’t think capacity has any bearing on longevity.
Longevity will be based on how many times the chemical reaction can be sustained.
I think this is mostly equal among all modern day high quality same-chemistry batteries.
Chemistry type, storage conditions, and charging rate are the factors that matter.
The 2500mah and 5200mah should last the same number of charges under the same conditions.

Zebretta
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Angler wrote:
Maybe HKJ will chime in here.

I can’t give you a scientific answer, but I don’t think capacity has any bearing on longevity.
Longevity will be based on how many times the chemical reaction can be sustained.
I think this is mostly equal among all modern day high quality same-chemistry batteries.
Chemistry type, storage conditions, and charging rate are the factors that matter.
The 2500mah and 5200mah should last the same number of charges under the same conditions.

My gut feeling is that you are correct.

I’m wagering that HKJ would say it makes no difference. But since I’m no battery expert, I thought I’d ask. Smile
I wasn’t even considering charges or use though TBH.

Just sitting on a shelf…un used….

Everybody keeps thinking I’m talking about suitability for a particular use or life through use or how many cycles it would last……lol

flydiver
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A harder thing to determine is battery/chemical/manufacturing quality. I think more than capacity those characteristics will determine how long a battery lasts…..given similar treatment. But that’s the rub, even decent batteries are capable of lasting years, and in that time will be subject to all kinds of treatment. Some people will be careful and conscientious, some will be abusive, some will be neglectful. I don’t think you can rely on manufacturing predicted cycles. It takes so long to do that I think a lot of those results are extrapolated. So you end up with mostly anecdotal reports to filter through.

So, I’d buy batteries that ‘in general’ seem to have a reputation for being a good product. I’d probably shy away from the ultra-high capacity (they have to do something to get that). Similarly unless you need it the ultra-high performance batteries are probably not too useful. I’d find “best buys” in known brand names of 2500-3000mA. For long term storage….50% capacity, airtight container, in the fridge. Maybe cycle them 1-4x/year. Or keep a few charged and rotate them through storage on a cycle.

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Zebretta
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Thanks flydiver. Sounds like good advice to me.

Phlogiston
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There is a possibility that manufacturers achieve the highest capacities by making the ribbon of materials thinner so that they can get more turns spooled into the same space within the cell. Hence the research into developing thinner, stronger separator and insulator layers.

That raises the chance that cell service life will reduce, if the manufacturer goes too far in the direction of making the ribbon thinner and packing more in.

In practice, however, I don’t think it’s likely to be an issue, because the device manufacturers to whom the vast majority of Li-Ion cells are sold will insist on a minimum service life anyway, capacity notwithstanding.

As ever, the best source of answers to these questions will be the manufacturer datasheets for the cells in question. Look for the part that tells you what percentage of total capacity is permanently lost over a given storage period. Sometimes, they’ll even provide that data for different storage voltages and temperatures.

Zebretta
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Phlogiston wrote:
There is a possibility that manufacturers achieve the highest capacities by making the ribbon of materials thinner so that they can get more turns spooled into the same space within the cell. Hence the research into developing thinner, stronger separator and insulator layers.

That raises the chance that cell service life will reduce, if the manufacturer goes too far in the direction of making the ribbon thinner and packing more in.

In practice, however, I don’t think it’s likely to be an issue, because the device manufacturers to whom the vast majority of Li-Ion cells are sold will insist on a minimum service life anyway, capacity notwithstanding.

As ever, the best source of answers to these questions will be the manufacturer datasheets for the cells in question. Look for the part that tells you what percentage of total capacity is permanently lost over a given storage period. Sometimes, they’ll even provide that data for different storage voltages and temperatures.

Good information.
Not sure how one would obtain those data sheets on many of the batteries for sale today.
The “manufacturer” on many of my batteries from GearBest and even IMRBatteries is only stated as “Made In China”
And even if they say “Panasonic”, how can we be 100% sure what we have?

ARsee
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There is a data sheet for the IMR 18650 30Q samsung 30Q.pdf

I stockpile CR123a's with a 10yr shelf life. Do 18650's come this way?

Speed4goal
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Imr provides a data sheet for every 18650 non rewrap on the site. The highest cycle count I’ve seen for newer cells is the mj1 at 400 cycles to 70 percent. The sheers will tell you how they figure that as well the discharge and charge rates. Its usually the worst conditions they use for it but not always. These cells are designed for devices usually tool packs which charge at 2-4 amps and medical devices and such

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