Some basic vape math questions

[cradleinflames]

So, I have a VAMO which supports up to 15W and a battery that supports up to 10A of continuous current (18A of pulsed current).

At 3.6V and 15W, you're looking at just under 4.2A of current, so my battery is safe in that sense in VW mode.

If I design my coil assuming a max current of 5A (should never get that high but good to have some wiggle room), I calculate at 3.6V and 5A, I get 0.72 ohms as my minimum resistance. If I wanted to do two resistors in parallel, I could do two parallel 1.5 ohm coils (resulting in 0.75 ohms total).

Am I better off doing dual 1.5 ohm coils or a single 0.75 ohm coil? And does my math/understanding sound right?

Let me know if I missed or overlooked anything. Thanks!

 

[3mg Meniere]

Vamo will not fire on anything less than 1 Ω. Mine said that a 1.1 coil was good-to-go, but I recoiled it. Next try came up at .6, and it said that that was a no-no. Next try was 1.3, and I decided to leave it at that.

 

[cradleinflames]

Hmm, good point, thanks for pointing that out to me! It looks like the minimum stated resistance for the Vamo is 1.5 ohms. I guess the most wattage I can pull is a little over 8.5W without stacking batteries. I guess I'll give that a shot and see if that's strong enough (I'm anticipating it will be for now, considering I'm moving from a simple Ego setup right now).

Would you recommend doing a dual 3 ohm coil setup or a single 1.5 ohm setup, from your experience?

Thanks again for the response, that's definitely a factor I didn't think about!

 

[dice57]

your math is right, just have the wrong mod, and batteries. 10 amp will work but will give out quickly when using max watts. Won't be able to fire your mod once the 10 amp bats voltage drops below 3.9 volts. Just not much usable power in a 10 amp continuous. 30 & 35 amp batts will run her til they's down to 3.4 or so.

With the newer generation regulated, like the dna30 devices, ohms of build takes second seat to style and optimal build. As long as she don't go to low she's good to 30 watts, even more on others.

I predict a dna or mech is in your future, definitely some decent batteries at the least. lol

Sounds like you are on the right path, keep up the good work.

 

[cradleinflames]

Out of curiosity, where are you getting this information about breakdown voltage and such? I don't understand how the amp ratings have anything to do with the voltage drop (or even the voltages themselves). From what you're stating, it sounds like my battery, which is rated at about 3.6V, won't fire up at all as it will be below 3.9V (unless that's a typo). Why would batteries rated at higher currents be able to run down to lower voltages? Wouldn't that be dependent on the mod they're in?

Regarding the max wattage, it already sounds like I won't be able to run max wattage anyway, due to the ohm limitations of the device. So that's kind of a moot point.

I'm not saying you're wrong, I just don't understand where you are getting this information. I have a pretty strong background in electronics and nothing about this makes any sense, so some source that talks about this would be very much appreciated!

 

[CreepyLady]

Hmm, good point, thanks for pointing that out to me! It looks like the minimum stated resistance for the Vamo is 1.5 ohms. I guess the most wattage I can pull is a little over 8.5W without stacking batteries. I guess I'll give that a shot and see if that's strong enough (I'm anticipating it will be for now, considering I'm moving from a simple Ego setup right now).

Would you recommend doing a dual 3 ohm coil setup or a single 1.5 ohm setup, from your experience?

Thanks again for the response, that's definitely a factor I didn't think about!

If you run in Watts mode on a VV/VW device you run at what you set it to. You are calculating this as if you were using a mech. If you make a 1.5 Ohm coil and set your watts mode to 15 and fire, then you are running at 15 watts.

 

[TomCatt]

The Vamo uses 'buck-boost' voltage regulation:

http://en.wikipedia.org/wiki/Buck–boost_converter

 

[cradleinflames]

Perfect, you answered my question! I wondered if it boosted the voltage up! So, I assume the boost voltage goes up to 6V, since it goes from 3-6V in VV mode.

So, if I'm at 15W with 1.5R, I have about 3.16A, which comes to be about 4.74V. Looks like I'm good to go then (since my current will be under 10A from the battery, though probably a bit less if the voltage is being boosted) and the 4.74V is under 6V.

Any recommendations between two 3 ohm coils or a single 1.5 ohm coil?

Thanks for your help!