Use battery DC power for Tesla coil

DC power in general

Tesla coils need high-voltage for primary coils and capacitors. However, achieving high voltage with pure DC power from batteries is very difficult. But there is another type of DC electricity generated by Faraday's DC generator which is a variable current. With Faraday's variable DC current, it is possible to increase the voltage by transformer
The DC current from the battery is very difficult to increase the voltage, so it will not be used to feed the Tesla coil.
DC current from DC generators can be used for Tesla coils, after going through the transformer, the voltage before reaching the capacitor is usually 25K volts or more.

Tesla coil: Magnifying transmitter – Nikola Tesla

DC power of battery

As mentioned above, we need to supply high voltage to the capacitor and primary coil of the Tesla coil, this is necessary because the spark gap needs to be as high as the "breakdown voltage" threshold. .
If only the battery is used to supply the Tesla coil, this means the transformer (increase voltage) from the battery.
The DC current of the battery can still increase the voltage by switching on and off to create a variable voltage.
A reed switch or a starter in a fluorescent light may cause DC power to be switched on and off from the battery.
Diagram of a fluorescent lamp using a starter to increase the voltage in a ballast:

A reed switch is also a way to generate variable current from the battery. However, we need to design the electromagnet generated by the coil and current from the battery itself accordingly, with the criteria of switching on and off at a certain frequency. If we want to make our own variable voltage from a reed switch, then we can learn a little more about it. Here, I just present the principle of implementation.

Learn more about the Tesla coil in another respect, for those who like to extend the properties of the Tesla coil:

• Free Energy Tesla Coil
• Explanation of Plasma on the Tesla Coil
• Convert electricity at the Tesla coil to power the engine

✰* Revealed At Last: Ancient Invention Generates Energy-On-Demand

✔ Nikola Tesla’s method of magnifying electric power by neutralizing the magnetic counter-forces in an electric generator

Generates Energy-On-Demand: Easy Power Plan Will Change Our World Forever

✔ Currents are 180 out of phase with each other, Lenz's law naturally is broken
✔ Principle of Resonance to achieve Overunity
✔ Generate generators without rotating motion, but based on the principle of rotating magnets. Because magnetism varies based on electronic circuit design: coils, capacitors, Negative resistance, etc.The change of magnetism does not require the rotation of the magnet.