The 2010 FIA technical regulations state:
5.8 Electrical systems :
5.8.1 Ignition is only permitted by means of a single ignition coil and single spark plug per cylinder. The use of
plasma, laser or other high frequency ignition techniques is forbidden.
5.8.2 Only conventional spark plugs that function by high tension electrical discharge across an exposed gap are
permitted.
Spark plugs are not subject to the materials restrictions described in Articles 5.13 and 5.14.
5.8.3 Other than for the specific purpose of powering KERS components, the primary regulated voltage on the
car must not exceed 17.0V DC. This voltage is defined as the stabilised output from the on-car charging
system.
With the exception of any KERS or capacitor circuitry or coils being used solely to provide ignition, any
device with a current requirement greater than 50mA or a power requirement greater than 1W may only be
supplied at or below the primary regulated voltage.
Only capacitor discharge ignition systems (those which generate a spark by means of closing a switch
which then discharges a capacitor through the primary side of the ignition coil), are permitted to provide a
voltage higher than the primary regulated voltage to an ignition coil.
Other than any parts being used to supply a higher voltage to devices such as those described in the
previous paragraphs, no device may step up or increase the primary regulated voltage.
http://argent.fia.com/web/fia-public.ns ... 0CLEAN.pdf
But as jake has stated, the basic electrical system for a Formula One car is pretty much the same as a production vehicle. An alternator supplies current, a battery is in the circuit, and that electrical power is used to power the ignition and any other tidbits. Sure, the parts are all custom built, and expensive, but in racing, every gram is important.
It's hard to argue against such a system, it's simple and reliable.
I too also wondered why someone didn't use KERS to power all auxilliaries, such as oil pump, water pump, and hydraulic pumps. Then again, all those extra electric motors could cause their own issues.
Racing should be decided on the track, not the court room.