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FrozenGate by Avery

IMREN IMR 26650 Batteries, are these the biggest tubular batts?

Alaskan

Alaskan

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I'm looking for some high current and capacity batteries @3.7V to stack 2X high for 7.4 VDC, the ones which seem to be the most I can get for a battery in a tubular form are 26650 batts, is this it? Anything with higher capacity? I don't need the 40-60 amps they are stated to be capable of, more like 15, but at 4200ma each for capacity those will run down fast when pulling 15 amps.

Suggestions?
 
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I've read not to buy batteries with the "fire" name in them, except for one. Because of that, I've kept away from them. I remember reading someone else say there is one exception, is this it? I see 5000, 5500 and 6000 ma rated batteries being sold on ebay in that package and don't know what to believe. I've seen photo's of batteries cut open and finding a much smaller one inside :p
 
You haven't said much about your application, but if you have any control over your build dimensions, then stay away from 32650s.

People go "gaga" over 32650s because they sound great from a dick measuring perspective, but they're stupidly crappy low-capacity cells when you actually stop to do the math on them and figure out their capacity relative to volume. Even granting 32650s their claimed capacity of 6,000 mAh (which is probably not real) they dramatically fail next to a good Panasonic 18650 cells (like those from LarryDFW).

32650:
6000/(65*(pi*(((32)/2)^2))) = 0.11 mAh / mm^2

18650:
3400/(65*(pi*(((18)/2)^2))) = 0.20 mAh / mm^2

See, a 32650 has only half the capacity per unit volume of a decent 18650. It's even worse if you compare apples to apples and use the true capacity of a 32650 for the comparison, instead of their made-up "6,000" mAh.

So, if you were going to make your cylinder 32mm to fit a 32650, why not make it 39mm and fit 3x 18650s instead? You'll get 10,200 actual mAh, instead of 6,000 pretend mAh.
how many 18 mm circles fit inside a 39 mm circle - Wolfram|Alpha

Or, if you can go 44mm, then you get 4x 18650s, for 13,600 mAh. That more than doubles, and probably triples, the true capacity of a single 32650:
how many 18 mm circles fit inside a 44 mm circle - Wolfram|Alpha
 
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You convinced me, thank you, change order in the works! But it will take two sets in series as I need 6 to 7.4 VDC at 18 amps.
 
are we alowwed to know what gadget is demanding 7.4v at 18 amps, fair bit of current there?
hmmmmm ..... curious:thinking:
 
Sorry, no secret, I didn't want to say until it is ready though, but doesn't matter; a multi-diode 520nm laser.

I have to confirm I can put eight each batteries in series parallel to produce the current and voltage I want. Looking at NiteCore's TM26 3800lm flash light with the extended time battery pack, using four 18650-like batteries in parallel, there are some hurdles to jump over to make it right and disaster proof. As far as I've been able to find, it isn't difficult with the right choice of 18650 battery.
 
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Laser Project said:
Sorry, no secret, I didn't want to say until it is ready though, but doesn't matter; a multi-diode 520nm laser.

I have to confirm I can put eight each batteries in series parallel to produce the current and voltage I want. Looking at NiteCore's TM26 3800lm flash light with the extended time battery pack, using four 18650-like batteries in parallel, there are some hurdles to jump over to make it right and disaster proof. As far as I've been able to find, it isn't difficult with the right choice of 18650 battery.
Click to expand...
Have a look @ NCR18650B or NCR18650PF they are all i use now, i dont even set eyes on other 18650s now
 
Thanks, I looked but I can't see what the difference is by looking, what is the advantage? Is the size the same as a normal 18650?
 
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I have heard that at that high current, even panasonics (the NCR ones) get warm, which is not a good sign. IWIRE tested several types and I believe concluded that imren was better for high amperage (as in it was the only one that did not get warm) at the cost of a few hundred mah. He was boosting for 4.4 A out to give an idea of the current. This is much less than u need, so I would figure the difference could be more pronounced. I use imren batts and I would recommend, but try asking IWIRE. He seemed to think that its better to err on the high side for the rated currents.

Also, even though the imrens have slightly less capacity, they charge faster.
 
OK, thanks. Now I don't know what to do, LOL... Four 18650 in parallel is about 4.5 amps each, if I buy the ten amp rated ones maybe that will work. Still, advice is appreciated, feed me!

:{)
 
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Just be sure that the rating you are looking at is for constant drain, not pulsed. But yes, since you have four in parallel, should be a fourth of the total drain on each. That's a lot of batteries :)
 
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