# 26650 vs 18650 Batteries ????



## Witterings (Aug 16, 2016)

I was looking at a couple of old threads I found doing some research of one vs the other and and a couple made reference that there was any greater capacity in the 26650'a than there was in the 18650's .... have I just stumbled across and old thread and they've now improved???

I googled keeppower 26650's and say they were quoted as 5200's .... I'm guessing that's a good number???


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## terjee (Aug 16, 2016)

Witterings said:


> I googled keeppower 26650's and say they were quoted as 5200's .... I'm guessing that's a good number???



About as good as they get.

There are two of that spec from Keeppower btw, one with protection IC, the other IMR. Also, as with 18650'ies, there's a risk of the cells being too long.


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## Chicken Drumstick (Aug 16, 2016)

Witterings said:


> I was looking at a couple of old threads I found doing some research of one vs the other and and a couple made reference that there was any greater capacity in the 26650'a than there was in the 18650's .... have I just stumbled across and old thread and they've now improved???
> 
> I googled keeppower 26650's and say they were quoted as 5200's .... I'm guessing that's a good number???


Good in terms of what? In order to gauge what is good and bad, a basic understanding of what you are dealing with will help you out loads.


Batteries have two major components, their capacity and their discharge rate. Depending on your use, one or the other is likely more important.

However as a rule, physically larger batteries can normally attain higher discharge rates. So most 26650's will out perform most 18650's in this regard. As well as having more capacity. The trade off being their size and weight.

The trouble is, 18650's have been somewhat developed more. So you get higher capacity for the relative size than you do with a 26650. But often to achieve this, it will have a negative affect on discharge rates.


If you look at batteries from the RC world, which use essentially the same technology as the Li-ion's we use in our torches, they will normally claim a C rating as the discharge amount. C means capacity in amps. And maybe be written such as

2000mAh LiPo 10C

This is saying the pack can be discharged at 10 x C.

So what is C?

2000mAh battery means C is 2amp. As C is the Capacity in Amps.

So 10C = 10 x 2 = discharge rate of 20amps.



Now it's important to note that batteries should have two discharge rates, although many quote only one or none at all.

-Continuous - what the battery can sustain for it's entire capacity
-Max or Burst - for short period of time only


If you constantly exceed the rated discharge rate, or get within say 75% of it. Then chances are the batteries cycle life will diminish. This is the number of times you can recharge it.

Pushing a battery hard will also cause it to heat up and generally perform worse, with much lower run times. So it's important to use a battery that is suitable.




Sadly the 18650's and 26650's we use in our torches usually lack the useful C discharge ratings. Although some may state in amps how they are meant to perform, but are usually over hyped. So we have to rely on sources like this:

http://www.lygte-info.dk/

Who does real world testing and lets us know how different batteries perform.


So what does this all mean.


Well it means a lot, as you need to know what you are wanting the battery to do.



If you have a low output light, or you intend to use the low modes. Then the amp draw is also very low. So a high capacity battery will meet the performance needs and offer the longest runtimes.


However, if you have a high output light with a high amp draw. Then you need a battery able to actually offer the amps in the first place and then sustain them.

In the 18650 world this is very easy to see the difference. Mostly because capacities of 18650's have been pushed so far.

Here are two very different batteries

1. 2500mAh high performance INR
2. 3400mAh high capacity ICR

On face value, most would assume 3400 is bigger and thus better than 2500. But that's a bit like assuming a car with an 18 gallon fuel tank is better than one with a 12 gallon fuel tank.

This graph shows what happens at a 5amp discharge.





To read this graph. The higher the line the better the output. The further to the right the longer the runtime.

Note the red lines are very high up. This means at this amp draw the battery is offering a good output voltage (remember voltage will sag under load and heat). You need the voltage to get the lumens.

So with both batteries completely fresh and fully charged, you can see the blue line is much lower. Meaning it wouldn't be as bright at maximum output. And as the battery discharges the blue battery always performs much much worse. So for any given moment, it would always be making less lumens.

The difference is, right towards the end, the red battery will suddenly not have any more to give. While the blue one will continue, but it would have been much dimmer for much longer and output massively down.


The conclusion here is. For performance, i.e. output. The smaller capacity battery is much better.


Now, lets turn this around. This graph shows the same two batteries, but at a very low amp draw. This is a moonlight or low output setting on a torch.





And it's a very different story. The blue battery can happily meet the performance requirements this time. So the performance between the two batteries is almost identical. The difference is, at such a low amp draw, the blue battery will keep on going for 20-25% longer.

So for this intended use, it is clear to see, the high capacity battery is a much better choice.



Now as I said, as a rule, physically larger batteries will tend to outperform smaller ones. So 'most' 26650's will offer better performance and runtime over most 18650's. But the same rules still apply. So it depends on your actual application to 'which' 26650 will be most suited for your use. e.g.


A 5200mAh 26650 and a 4200mAh.

At 5amps the 4200 battery clearly offers a better voltage curve. So will be brighter for longer than the 5200 battery.






But at 0.5amps the tables are turned.


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## sidecross (Aug 16, 2016)

Chicken Drumstick said:


> Good in terms of what? In order to gauge what is good and bad, a basic understanding of what you are dealing with will help you out loads.


+1

Thank you for writing a good explanation that will help explain what and how batteries work in flashlights.


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## Witterings (Aug 16, 2016)

Chicken Drumstick said:


> Good in terms of what? In order to gauge what is good and bad, a basic understanding of what you are dealing with will help you out loads.



Corrr CD ... quite a bit of useful info there 

I was really only after a very simple yes they are close to the stated 5200 mah quoted or whether it was a fictitiously high figure and wouldn't have anywhere near the capacity quoted and most people suggest Trustfires figures are massively exaggerated but thank you for such a detailed response and some very useful info.
I do actually have a reasonable knowledge of batteries ... as you say they're very similar to RC ones and I've flown RC planes, helis and multirotors including doing some commercial work for over 12 years so am reasonably familiar with LiPo technology.


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## akhyar (Aug 16, 2016)

Very good details explaination there CD.
My only gripe with the 26650 batteries nowadays are that we don't normally know the base cells used and the makers of these base cells, unlike the 18650 batteries where most of them are either made by Panasonic/Sanyo, Sony, Samsung or LG, and maybe few made by some Chinese manufacturers.


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## sidecross (Aug 16, 2016)

Witterings said:


> I was really only after a very simple yes they are close to the stated 5200 mah quoted or ....


I have switched from 18650 battery flashlights to 26650 lights for my daily use; I do use a 18650 light (ZebraLight SC600 Mk3) for edc.


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## Chicken Drumstick (Aug 16, 2016)

Witterings said:


> Corrr CD ... quite a bit of useful info there
> 
> I was really only after a very simple yes they are close to the stated 5200 mah quoted or whether it was a fictitiously high figure and wouldn't have anywhere near the capacity quoted and most people suggest Trustfires figures are massively exaggerated but thank you for such a detailed response and some very useful info.
> I do actually have a reasonable knowledge of batteries ... as you say they're very similar to RC ones and I've flown RC planes, helis and multirotors including doing some commercial work for over 12 years so am reasonably familiar with LiPo technology.


Do you know which specific 5200 battery you are looking at? I believe Keeppower have made more than one.

And also where you are buying from, as some sources are more likely to be fakes.

Your best bet is to use the link I provided earlier for HJK's website. It's a font of useful battery knowledge. Use this link for a battery comparator.

http://www.lygte-info.dk/info/indexBatteriesAndChargers UK.html

But do remember the application. A battery might make it's claimed capacity at a lower amp draw and significantly fail to meet it at a higher one.


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## KeepingItLight (Aug 16, 2016)

Thanks, Mr. Drumstick, for posting such a well-written explanation. It gets my vote for best post of the week.

If you had posted this in a separate thread, with a title such as "A Primer Comparing Li-ion Capacities and Discharge Rates," I would have voted to make it a sticky!

Nice job.


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## sidecross (Aug 16, 2016)

KeepingItLight said:


> Thanks, Mr. Drumstick, for posting such well-written explanation. It gets my vote for best post of the week.
> 
> If you had posted this in a separate thread, with a title such as "A Primer Comparing Li-ion Capacities and Discharge Rates," I would have voted to make it a sticky!
> 
> Nice job.




+1


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## Stereodude (Aug 16, 2016)

Chicken Drumstick said:


> To read this graph. The higher the line the better the output. ...


That's not necessarily true. If the light is constant current regulated the output will be the same.


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## sidecross (Aug 16, 2016)

Stereodude said:


> That's not necessarily true. If the light is constant current regulated the output will be the same.


I would think that HJK would keep his testing with what you write in mind, and that testing would be equitable.


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## Chicken Drumstick (Aug 16, 2016)

Stereodude said:


> That's not necessarily true. If the light is constant current regulated the output will be the same.


This could be the case, but would depend on the level of current it was trying to maintain. And it would also depend on the type of driver.

For most Cree LEDs in 1xli-ion flashlights, they use what is known as a linear driver. These will regulate current as a constant output, but require the battery to be able to deliver a voltage that is similar to the vf of the led. 

An XM-L2 or XP-L requires 3.x volts.

So a battery part drain may not be able to deliver the voltage required. Or if the battery suffers a voltage sag under load.

Most of our tube style single Li-ion lights will pull 2.5 - 3.1 amps on high. Many ICR's will struggle at 3 amps and will suffer voltage sag. When this happens the light will fall out of regulation, and often drop to a lower mode, or just not make the output it could in that mode.

To relate this back to the charts and batteries under discussion, the difference here is, at say a 3amp constant output. You are correct the PEAK output is likely going to be the same or similar. The difference however is, the high performance battery will be able to maintain regulation for longer, because it will maintain the require voltage for longer.

Lights that use a boost driver work differently, but as a rule, the higher performance battery will still give better high output results, either in PEAK and/or duration.


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## nfetterly (Aug 16, 2016)

I ordered the Keeppower IMR 26650 today (from Illumn, should be no fakes there). 

Have the new Olight R50vn (Vinh's "upgrade" - at basically MSRP). Great light.

Real world use I would have a hard time telling the difference between cells with it.


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## sidecross (Aug 16, 2016)

I would think that the tests that HKJ has provided would have had the results based on the same source of power drain; to compare two batteries using two different sources of battery usage or drain would be absurd.

The 'Battery Comparator' results that HKJ publishes seem a good first place to evaluate differences in batteries.


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## Witterings (Aug 16, 2016)

Chicken Drumstick said:


> Do you know which specific 5200 battery you are looking at? I believe Keeppower have made more than one.
> 
> And also where you are buying from, as some sources are more likely to be fakes.



Having done a search probably from either banggood or gear best, here's one of the links I found 
http://www.banggood.com/Keeppower-I...ted-Rechargeable-Li-ion-Battery-p-961178.html

here's the other
http://www.gearbest.com/chargers-batteries/pp_104844.html

I haven't decided on the torch yet although me considering them was inspired by seeing the Palight MS600 and was more an enquiry about teh batteries before making a purchase I regretted (should have said ANOTHER purchase I regretted  ) .... but generally as long as it's 250 + real lumens and is focus adjustable my next priority is run time and thought these might be better than 18650's ....


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## CuriousOne (Aug 17, 2016)

A special notice - HKJ gets batteries directly from vendors for review, so it does not means that you will be able to buy same quality batteries, as were reviewed by him. I personally 4 times already met when the battery in HKJ's test was great, but in real life, it was erm....


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## SG Hall (Aug 17, 2016)

Good explanation Chicken Drumstick. I've only recently starting looking at the battery comparator, somehow I missed it before then. It was a complete eye opener. 

Your post is a great reference for those who get lost in the information! 

The new VTC6 looks like an interesting alternative to the Samsung 30Q. [emoji106]


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## HKJ (Aug 17, 2016)

CuriousOne said:


> A special notice - HKJ gets batteries directly from vendors for review, so it does not means that you will be able to buy same quality batteries, as were reviewed by him. I personally 4 times already met when the battery in HKJ's test was great, but in real life, it was erm....



From vendors I do not believe that there are any risk, it is more from manufacturers. It can be because they are cheating or it can be because they cannot get a specific cell to rewrap and then uses another (That can also be called cheating, but if their specifications are very vague, they will still be within them).
I do also buy some batteries myself from a couple of different shops.

My reviews always list where I got the batteries from.

One reason I post reviews here is because it allows sharing of experience, like when you get bad batteries you can share it in the review thread.


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## Chicken Drumstick (Aug 17, 2016)

Witterings said:


> Having done a search probably from either banggood or gear best, here's one of the links I found
> http://www.banggood.com/Keeppower-I...ted-Rechargeable-Li-ion-Battery-p-961178.html
> 
> here's the other
> ...



My personal preference would be to go for IMR's, as they don't have the protection circuit. Although less likely on a 26650, but I find it annoying on some lights, that once the battery drops, you can trip the protection circuit leaving you with no light at all. I'd rather have a light that still works, or leaves me with the choice if I want to continue using it or not.

The battery comparator I linked to earlier shows these batteries as performing similar to each other at 3amps. So either is probably fine.


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## Witterings (Aug 17, 2016)

Chicken Drumstick said:


> M I'd rather have a light that still works, or leaves me with the choice if I want to continue using it or not.



This is so true ... I also want something for cycling which be dangerous if it just cuts out ..... one of the torches I used gave out 2 flashes a minute when the battery was getting low ... wish they all did that and thanks again!!! 
Whereabouts in the UK are you ... we seem to be in the minority on here??


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## Chicken Drumstick (Aug 17, 2016)

Milton Keynes area on the Beds/Bucks boarder. Yep not too many Brits on here, but a few.


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## sidecross (Aug 17, 2016)

Witterings said:


> This is so true ... I also want something for cycling which be dangerous if it just cuts out ..... one of the torches I used gave out 2 flashes a minute when the battery was getting low ... wish they all did that and thanks again!!!
> Whereabouts in the UK are you ... we seem to be in the minority on here??


I would rather trust my knowledge than some 'fail-safe' device made for people without an ability to think and decide.


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