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18650 vs. 16340?

EpicHam

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Yeah I think you may be talking about the current draw influencing in a li-ion capacity. When discharged at a lower rate (lower current), the battery lasts longer.
With the DC/DC converters we use, assuming we would need uh, 20W from a li-ion, that would make sense.

Assuming 100% efficiency
4.2V = ~4.76A drain
8.4V = ~2.38A drain
16,8V = ~1.19A drain

So we know that if you drain 5A from a crap 18650 it won't last long. Its life and capacity is severely lowered in some cases.

Anyways multiple (2 in this case) 16340 cells are better for high drain applications IMO. BUT a single (in this case) 18650 is better for size, capacity, at lower drain.
(Heck, if you're draining 20W from batts, you should just build a 3x or 4x 18650 host)
 

BShanahan14rulz

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Yes, your reply was actually more informative, while I was mainly voicing my opinion in an annoyingly terse form.

There is one more reason to pick 18650, though: it is a standard cell size that is made by just about every lithium ion cell manufacturer.
 

hwang21

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Yes^ most laptop batteries use 18650 configuration, it is a very common battery type :beer:
 
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18650's are more advanced than (most?) 16340's, and have better energy density. My 16340's are 700mAh capacity, my 18650's are only twice as long but hold 4 times as much (2800mAh). Or so they claim. The 16340's are Soshine the 18650's are LG, decent stuff.
 

xmtgx

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Anyways multiple (2 in this case) 16340 cells are better for high drain applications IMO. BUT a single (in this case) 18650 is better for size, capacity, at lower drain.
(Heck, if you're draining 20W from batts, you should just build a 3x or 4x 18650 host)
Standard li-ion cells can discharge safely at 2c. So a modern 18650 (3400mah cells) are around 3200mah. They can safely put out 6amps. Where as a single 16340 can only discharge at around 1amp. So this isn't exactly the case.

IMR's can be safely discharged at 5c. In this case a 16340 can handle about 2-2.5amps

Marco Polo said:
18650's are more advanced than (most?) 16340's, and have better energy density. My 16340's are 700mAh capacity, my 18650's are only twice as long but hold 4 times as much (2800mAh). Or so they claim. The 16340's are Soshine the 18650's are LG, decent stuff.
This is true because 16340's aren't really used outside of hobbiest applications so there isn't much rnd going into them AND you have to remember that if you have a protection circuit it takes up a LOT more of the cells space in comparison to the 18650 so you have almost 2.5x the cell size.

Also your 16340s are more like 450-550mah not 700.
 




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