Fluorescent tubes use
far less energy than incandescent lamps and fluorescent tubes last a
great deal longer as well. Other advantages are diffuse, glare-free
lighting and low heat output. For these reasons, fluorescent lighting is
the natural choice in commercial and retail buildings, workshops and
factories. For battery-powered lighting, fluorescent lights are also the
first choice because of their high efficiency. The main drawback with
running fluorescent lights from battery power is that an inverter is
required to drive the tubes.
switch-mode circuits are involved here: the DC-DC inverter involving
IC1, Q1 & Q2 and the fluoro tube driver which converts high voltage
DC to AC via IC3 and Q3 & Q4 in a totem-pole circuit.
Inverter efficiency then becomes the major issue. There are many
commercial 12V-operated fluorescent lamps available which use 15W and
20W tubes. However, it is rare to see one which drives them to full
brilliance. For example, a typical commercial dual 20W fluorescent lamp
operating from 12V draws 980mA or 11.8W. Ignoring losses in the
fluorescent tube driver itself, it means that each tube is only supplied
with 5.9W of power which is considerably less than their 20W rating. So
while the lamps do use 20W tubes, the light output is well below par.
This circuit generates in excess of 300V DC which could be lethal.
Construction should only be attempted by those experimenced with
mains-level voltages and safety procedures