Lexicon

Ohm

The ohm is the SI unit of electrical resistance with the unit sign $\Omega$ (big Greek Omega). It is named after the German physicist Georg Simon Ohm. For us vapers, Ohm and the associated Ohm's law are particularly important when we wind ourselves. Ohm's law allows the current strength to be calculated with the resistance used. This way we can be sure not to overload the battery(s) and thus prevent the batteries from degassing. The following image shows the formula change:

$R={\frac {U}{I}}\quad \Leftrightarrow \quad U=R\cdot I\quad \Leftrightarrow \quad I={\frac {U}{R}}$

Explanation of letters: R = resistance, U = voltage in volts, I = current in amperes

The third calculation is interesting for us because we can use it to calculate what current is required.

For example:

You have a winding with a resistance of 0,15 ohms, and when the batteries are full there is a voltage of 4.2 volts - so 4,2 volts divided by 0.15 ohms equals 28 amperes of maximum load when the batteries are full. This means that batteries with at least 30 amps must be used (we also want a little safety buffer)

(Source partly from: https://de.wikipedia.org/wiki/Ohm and https://de.wikipedia.org/wiki/Ohmsches_Gesetz)