How popular does DC power use in high voltage? For example, 400V,90V DC?

Question

I am doing a project about "Use of Batteries as Power Sources", but I cannot think of anything that is using batteries as HIGH DC power sources or as a back up power for.

1) Can anyone give me more examples of what equipments, nowadays or in the past, use High DC voltage or DC energy. (NOT things about MP3 etc)

For example, 90 V DC would power a vintage valve portable radio.
Car battery would need to step up the voltage from 14V? to ????volt to make a spark for starting an engine, these kinds of things.

2)Can anyone suggest any websites that supply knowledge of what high DC power can do? (better if there are pictures and professional information)

3) Any suggestion for what equipments are needed or would be good if they use DC power in the future?

Answer 1

In the old days of tube (valve) radios in cars the plate voltage was provided from the 12V battery by electronics. In the same era for "portable" radios they usually had a string of 1.5V cells that added up to 90V or so for the plates of those tubes.

Nowadays low voltages are usually put through electronic double rs or quadruple rs or are passed through an oscillator that makes rough AC for a step-up transformer and then is rectified if high voltage DC is needed. An electric fence would be an example.

A car battery only provides 12V. The generator charges that with 14V. Anything used in the car is expecting to see 12V but can tolerate the 14V without failing.

In a car the 12V is passed though an interrupter to make a very crude AC that will power an ignition transformer to make the voltage needed for the ignition sparks. In most modern cars all of that interruption and step up are done electronically to make a very compact ignition package.

DC is too limiting to use by itself (even though that is what fuel cells put out) so there is always going to be accompanying electronics to transform it as needed for applications in the future.

Answer 2

banks of batteries are used for emergency lighting (rectified) in large buildings when the power goes out, or to the run electric powered hi-lo's