Ok ohms law and batteries... This will be long...
I=V/R
Lets put words in for what the letters stand for...
Current = Volts/Resistance
This is the first and most important use of ohms law... The Amps's expressed is the Voltage divided by the Resistance.
This is the number you compare to the Amp limit on the battery...
Then comes along the man named James Watt...
James needed a way to express the rate of energy transfer...
He defined a Watt as 1 Joule per Second...
Da Fuq? Is this guy a wizard? We are talking about treasures and time now... Are we wiring up a Flux Capacitor?
No see Watts are actually how power is transferred... The easiest way to express that is through kinetic energy, the energy of motion...
So lets get the electrical conversion for Watts so we are not talking about Joules and Newtons... So...
P=IV
Or in words...
Power = Current times Voltage
But we determined Current = Volts/Ohms
So lets substitute that in using base algebra...
Power = Volts times Volts divided by ohms...
Ok now that we got that all worked out the 2 math problems you have to remember is Amps = Volts/Resistance and Watts = Volts times Volts divided by ohms...
As far as your battery rating think of that like a speed limit... It is a sign saying do not let the current go above this number.
As far as the kick, what the kick does is runs the above calculations over and over and over...
The kick will turn up and down voltage as needed to hit a specific wattage.
So for example lets say you have the kick set to 10 Watts...
Your coil is a 1.00 ohm coil...
The kick will take the input of the battery but only output 3.162278 Volts...
Now same battery and same coil lets say you crank it all the way up to 15...
The kick will output 3.872983 volts...
So what is happening with the kick is it is changing the voltage for you...
Variable wattage is variable voltage that adjusts for you automatically...
Where amps come into play is sub ohming...
So lets say I have a Sony VTC5 (30 amp battery)...
And lets say I have a 0.20 ohm coil...
And lets say I have a full 4.2 Volts, the amount a full charge is, expressed to the coil...
I am getting 88.2 Watts at 21 Amps...
The 21 Amps expressed to the atomizer is lower than the Amp limit of the battery, so life is good...
Now lets say next time I build the coil I loose...
I leave a wrap off my build and my coil is now 0.08 Ohms, and once again I am getting the full 4.2 Volts to the atomizer...
I am now getting 220.5 Watts at 52.5 Amps...
I am breaking the amp limit...
By a lot...
Almost doubling it...
This is where you really have to be careful because you are now running on pulse limit...
Pulse limit is a funny thing, think of it like the cop deciding if you are getting a ticket or not...
If you are running 10mph over the speed limit for a long time it is more likely to get a ticket than if you are running 10mph over the speed limit for a very short time...
But I hear about people running .08 Ohm coils...
Why yes you do...
And anyone that is running a .08 Ohm coil is not running at 220.5 Watts...
Because on a mechanical you never get full power from the battery...
This is referred to some times as voltage drop or battery sag...
This is dependent on the amount of work the battery has to do, also known as "Under Load"...
The amount of internal resistance of the battery has a lot to do with sag as well...
So for an example I have a Sony VTC 5...
Let's say it is 4.2 Volts unloaded...
Loaded it is firing at 3.7 Volts...
I have a 0.13 Ohms atomizer...
If the full 4.2 Volts were expressed to the atomizer...
I would have 135.6923 Watts at 32.30769 Amps...
This would be exceeding the amp limit and putting me on my pulse limit...
But remember we are not getting all of that power due to sage...
So at 3.7 Volts I would actually be getting 105.3077 Watts at 28.46154 Amps...
This is a huge change in wattage but it is actually not under pulse limit...
So let's turn this back into regulated mods as your question is about the kick...
The job of the kick is it takes a mechanical mod and changes it into a regulated...
So I am going to take something a little more powerful than the kick for this example...
Let's say there is a kick that goes to 30 Watts!
Let's say that kick will read down to 0.20 Ohms!
The amp load on that would be 12.24745 amps...
Well with in the amp limit of the batteries...
There you go that is my really really long over complicated answer.