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Author Topic: How low can you go  (Read 12231 times)

Offline Jerry

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Re: How low can you go
« Reply #25 on: March 16, 2015, 11:00:21 PM »
Was that it depends on the coils battery that we used? Most batteries are in good condition if those batteries are in good quality.
 

Offline failte

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Re: How low can you go
« Reply #26 on: March 16, 2015, 11:35:59 PM »
Was that it depends on the coils battery that we used? Most batteries are in good condition if those batteries are in good quality.

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Offline danwldr

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Re: How low can you go
« Reply #27 on: March 17, 2015, 12:14:36 AM »
Was that it depends on the coils battery that we used? Most batteries are in good condition if those batteries are in good quality.

Its not the quality of having a new battery, stay away from batteries that have fire in their name, there is a reason its there!

Always use branded batteries purchased from a reputable dealer as many batteries are cloned also.

Just stay as safe as possible, know what you are doing, and keep your face :)+1
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Offline glen johnson

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Re: How low can you go
« Reply #28 on: April 02, 2015, 07:08:09 PM »
I only use the Samsung inr 25r batteries and I run coils to .1 ohms for 8 months now and have never had a problem at all. I have even built a coil to .08 ohms and had no problems. I do not recommend newbies to run coils this low because it can be dangerous with a clone mod that shorts out.

Offline ItTechy

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Re: How low can you go
« Reply #29 on: April 21, 2015, 11:40:26 PM »
Very good reference!

Great Post!  :()()
Vaping for over 6 years now!

Offline CraigHB

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Re: How low can you go
« Reply #30 on: April 22, 2015, 05:05:24 PM »
I haven't looked at this post before but decided to click on it when it came up in the list of recent threads.  The original post is over a year old.  Are people running those super low resistance coils as much lately?  Or is it a novelty that has sort of worn off.  I know resistances around a half Ohm are popular now, but are people still regularly running coils down to a tenth or two of an Ohm?

In that chart it looks like the author is simply using the max cell voltage (4.2V) divided by the max continuous current to recommend a minimal safe resistance, which is a good policy.  You want to avoid running into the burst region of loading since cells get inefficient when loaded that heavily.  You sacrifice a lot of run time for it and you can get to a point of diminished returns where lowering resistance doesn't do anything other than reduce run time.

With an e-cig it is possible to run into the burst region of battery loading without safety issue.  Though you can assume plus 50% over the continuous rating when it's not specified so I'm not sure where the burst limits are coming from in that chart.  Even for the continuous ratings it can be hard to find official published specs for a lot of batteries.   Sometimes they specify burst limits in battery data sheets, usually not.  For example the HE2 data sheet specifies a 35A burst with a 20A continuous rating.  The plus 50% rule would be 30A burst for a 20A continuous rating so that one even has a bit of an advantage there.

When getting into extremely low resistances the current path between the battery and atomizer and the resistance of the battery itself can also be considered.  For example, there's probably an addidtional 50mΩ in the current paths and another 15mΩ in the battery for a 20A 18650.  For a 100mΩ atomizer maximal current would be maximal battery voltage divided by 165mΩ rather than 100mΩ.  Ultra low resistance atomizers may be drawing less current than people think.

Of course, all this applies only to mechanical mods where you can consider max battery loading in terms of atomizer resistance.  This all becomes irrelevant for high power regulated mods which are popular now.  In that case you have to think in terms of power, not resistance. 

For example, maximal power output for a 20A battery would be minimal battery voltage times maximal current.  Using the continuous limit, a 20A 18650 would have a maximal output of 3V (a typical minimum) times 20A for 60W.  So you wouldn't want to use a single 20A 18650 in a 100W mod.  You would need two 20A 18650s for an available supply power of 120W.
« Last Edit: April 22, 2015, 05:15:38 PM by CraigHB »

 


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