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2s2p mods vs 3s mods
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Don Offline
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Post: #21
RE: 2s2p mods vs 3s mods
(07-01-2017 02:11 PM)gentlydoingit* Wrote:  Which mod has the longer run time, a 2s2p or a 3s? On the face of it its a simple answer, 2s2p has one more cell!.. but the time taken to get 12v down to 3.4v vs 8.4v down to 3.4v also smacks of an obvious answer.. both sets of numbers are in the same question if you see what I mean. Not knowing the total mah of either pack isn't helping me Huh

3S - let's do this with 18650s. So 3x 2500mAh and 22A though I'd not be wild at running a set of three in series at their maximum rating. For the moment we'll ignore the massive capacity loss at max current and the voltage drop. And let's convert to watts to see the actual energy involved. So we have 12.6V at 22A gives us 277.2W. Now that's 22,000mA so it can keep this up for 2500/22000 hours or 0.114 hours which is about 7 minutes.

Now a watt is a joule per second so we are pulling 277.2 joules per second for 409 seconds so that's 11.34 kilojoules available or if you prefer 31.4 watt hours.

Now for 2S 2P. So that's 8.4V and 44A which is 369.6W. So we have 5000mAh available which well now convert to amp seconds. So we have 5x3600 amp seconds available which is 18,000. We are pulling 44 per second so we have 409 seconds at 44A. Which gives us 151,200 watt seconds which we divide by 3600 to get Wh. Which gives us a nice round 42Wh. So the 2S 2P should last longer.

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07-01-2017 08:14 PM
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Don Offline
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Post: #22
RE: 2s2p mods vs 3s mods
I assume the DNA250 is like the 200 in that it will max out at 133W with 8.4V into it.

It needs the volts to keep the current through the chipset below ignition levels. They never work so well once the magic smoke gets out.

TVF tested battery info to be found here

http://www.preventsuicideapp.com

[Image: 24291313393_16615b20b2_m.jpg]
07-01-2017 08:16 PM
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Michael (01-08-2017)
ecignut Offline
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Post: #23
RE: 2s2p mods vs 3s mods
Hey gently I told you right at the start that 4 batteries would be best[Image: tongue.gif]. Was this the only 'current' problem you had.
It is time for another question now - ask us another[Image: tongue.gif].
07-01-2017 09:14 PM
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Don29palms Offline
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Post: #24
RE: 2s2p mods vs 3s mods
Is there a DNA 250 mod that takes 4 18650s?
07-01-2017 09:24 PM
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Don Offline
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Post: #25
RE: 2s2p mods vs 3s mods
Not that I know of - the DNA250 is relatively new to the market. You'd actually want 6 in a 3S2P configuration. That should work pretty well but would be a monster mod.

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07-01-2017 09:32 PM
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gentlydoingit* Offline
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Post: #26
RE: 2s2p mods vs 3s mods
Thanks Don. Good Thank_you2

Don't forget to apply for the freecycle section!
http://www.thevapingforum.com/Forum-FreeCycle--191
07-01-2017 10:02 PM
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Michael (01-08-2017)
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Post: #27
RE: 2s2p mods vs 3s mods
Thanks for the science and maths, Don Smile I'm glad I reached the correct answer, though by the wrong means Tongue
08-01-2017 01:40 AM
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Umi (01-08-2017)
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Post: #28
RE: 2s2p mods vs 3s mods
science and maths Huh I think I'll stick to ??????????? when I think of something I'll post itTongue

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08-01-2017 02:07 AM
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