100 watts and under what battery do I need?

[Davidl41]

The battery I have is a 30A samsung 25r (some say there is only a 20A version and mine is a fake?). If I was to vape at 80 watts or 120 watts what type of battery would I need.

How do I calculate the wattage, volts and the battery amp discharge to come up with the right calculation.

 

[State O' Flux]

Ohms law will provide the answers you seek. If you use 4.2V as a fully charged constant (personally, I use 3.8~4.0V, as 4.2 is fairly short lived), along with the "desired" resistance... the remaining values of wattage and amperage fill in.

Click all the hyperlink siglines below. Steam Engine has a Ohm's law calculator as an accessory to it's excellent coil modeling program. The last hyperlink is to Mooch's 18650 battery test series... the only completely objective and vaping related 18650 test series on the interweb.

 

[Slurp812]

I assume a 2 18650 mod? With regulated mod, the resistance isn't used on the battery side of things in calculations. With regulated mod, there are 2 sides. On the battery side, I like to use a approximate voltage from a discharge chart. Say ~3.6 volts per cell. So, we have 7.2 volts in a 2 cell series mod. We set the device to 120 watts. 120/7.2 = 16.67 amps. To the batteries this looks like a 0.432 ohm load. We also have to remember circuit losses. So the battery side will be a bit higher. On the atty side, say we have a 0.2 ohm atty. To get voltage from power and resistance, its the square root of P/R so I use the Ohms law calculator. So at 120 watts, 0.2 ohm load, the atty would see 4.89 volts at around 24.5 amps.

120 watts
Battery side:
~7.2 volts under load
~16.67 amps (slightly more due to losses)
looks like a 0.432 ohm load to the battery.

atty side:
0.2 ohm load
~4.89 volts
~24.5 amps