How do lead batteries (rechargeable) supply both AC and DC power?

[khurram usman]

lead battery(rechargeable)...?

i was just wondering that the common lead batteries (the ones used in cars) supply us AC or DC? i saw a battery attached to a UPS and it steps up the 12V to 240V. so what i concluded was that it must give us AC. but how does it supply AC? i mean its positive and negative terminals are fixed. also i remember reading somewhere that they supply us DC. please explain.

 

[russ_watters]

All batteries supply DC. To turn it into AC you need an inverter.

 

[khurram usman]

All batteries supply DC. To turn it into AC you need an inverter.

ok...how does an inverter work?

 

[Borek]

http://lmgtfy.com/?q=how+does+an+inverter+work

 

[hisham.i]

Great link Borek

 

[Naty1]

Batteries produce voltage and current in a fixed direction due to chemcial reactions. So one terminal of a battery is positive and the other negative as electrons and ions from chemical activity move between the terminals.

An inverter takes the fixed polarity battery energy (power) and switches it from positive to negative (a square wave is a simple result) via electrical components while more sophisticated electronic oscillators not only switch from positive to negative but also produce a sinusoidal waveform...like that from commercial power.

More here:
http://en.wikipedia.org/wiki/Electrical_inverter#Circuit_description

It makes no difference that some batteries are rechargable...all that means is that the chemical processes can be reversed by application of external power which restores (most of) the battery chemical composition.