Ohm's Law Question ANSWER ASAP (:

[CLOUDKICKER]

hi ECF users,

Im still relatively new to mech mods and was wondering how i use the ohms law calculator? I know i put the resistance of my coil as one of the numbers but for the volts, do i put the full charge voltage of the battery or just the regular voltage they say? So for example the coil i built was 0.3 resistance and the battery saids 3.7 voltage and 4.3 full charge voltage, which one do i insert, 3.7 or 4.3?

Thanks sooo much! Sorry about being annoying or anything but im trying to vape safe.

 

[ckquatt]

State of Flux answered your question in your other thread.

http://www.e-cigarette-forum.com/forum/batteries-chargers/641466-battery-help.html#post15008535

Its the second post.

If math is hard... use an on-line Ohm's law calculator - where 4.2 volts is a constant value - then insert your resistance value and hit the "calculate" button. Add 10%, and again, you have your minimum amp requirement.

 

[Baditude]

I give a detailed explaination in this blog: Explain It To The Dumb Noob - Ohms Law Calculations.

Always use 4.2 volts of a fully charged battery for your formula.

 

[CLOUDKICKER]

so i input 4.2 as my volts and then i inserted the resistance so for example my coil is 0.35. so i get my total amps so on the calculator its about 12A and then after i add 10% headroom give or take which is like 13A. so now as long as my battery max discharge is not below 13A im good, correct?

 

[CLOUDKICKER]

so i input 4.2 as my volts and then i inserted the resistance so for example my coil is 0.35. so i get my total amps so on the calculator its about 12A and then after i add 10% headroom give or take which is like 13A. so now as long as my battery max discharge is not below 13A im good, correct?!

 

[DreamWithin]

Yes, that is correct

Using 4.2 volts in the calculator automatically gives you some headroom. Typically there will be some sag in the actual output voltage when put under a heavy amp load, so using that maximum value accommodates somewhat for "worst case scenario" situations. Hence why it's recommended to use that number

 

[jwag1973]

DreamWithin gave you a good answer. I'm not sure what batteries you're using, but I'd have Sony VTC4 / VTC5 (30A ) and Samsung 25R's, which are 20A batteries. I also use Purple Efest 18650 2100mah 30A batteries, though I haven't seen any credible test to prove they are true 30A. I give myself a little more headroom, as I personally prefer to leave around a 10A cushion if possible. I usually don't "sub-ohm" below 0.6 ohm. If you do, make sure you have some good batteries, preferably the Sony's. RTD VAPOR has them in stock, they sell genuine cells. Good luck, vape safe!

 

[Bunnykiller]

so i input 4.2 as my volts and then i inserted the resistance so for example my coil is 0.35. so i get my total amps so on the calculator its about 12A and then after i add 10% headroom give or take which is like 13A. so now as long as my battery max discharge is not below 13A im good, correct?!

as long as the amp draw is not more than 13 A so you should have a battery rated for 13+ A

 

[Slurp812]

Lots of sag with a .3 build! According to the discharge charts of a vtc5, at 10 amps (ballpark value of this scenario) you would be maybe around 3.6-3.7 with a full battery while firing. So for the actual calculations I would use 3.7. Using this it came out to 12.333 amps, and ~45 watts. It would of course drop from there. Also you would have some voltage drop in the mod. But still a kickin vape for sure...