Afternoon Dudes,
What is needed is higher wattage bulbs, not lower
voltage bulbs -- while the later produces the former,
if less stable. Also, if your alternator voltage regulation
is flakey, you could easily burn out the bulbs with all-but
twice their rated voltage (14+ volts)! Then again, if you
'up' the wattage of the bulbs, you could fry your reostat.
I would suggest that if one uses higher wattage bulbs,
that one also jumper across the reostat to avoid it's
damage. I mean, the goal is MORE light anyway. A
reostat on a classic British car's panel lights is just about
the most useless thing in automotive engineering.
The increase in current draw should not be so much
as to threaten your wiring. Here's the math.
P = IE
and,
E = IR
where,
P = power, in watts
I = current, in amps
E = voltage, in volts
R = resistance, in ohms
Resistance is tricky with lamps because it the the HOT
resistance of the filiment that goes into the formulae, not the
resistance one would read when testing a lamp with a volt-
ohmmeter.
An example, not specific to the MGB:
Illumination uses 8, 5w, 12v bulbs. Therefore, the current
drawn is: 8 x (P/E) or 8 x 5/12 or 3.3 amps. If you upgraded
to 8w, 12v bulbs, the new current would be: 8 x 8/12 or
5.3 amps.
Put your own numbers into these formulae and compute
the current draw for your choice of bulbs. From that, you
can decide if the reostat can take it and what size fuse needs
to be used. Also, please remember that power is power and
wasted power is wasted power. Higher wattage lamps also
produce more waste called HEAT. Many of us have seen
electronic or automotive equipment where an incorrect bulb
in the pilot light has melted the colored plastic 'jewel'.
Perhaps this helps.
best Monday to all,
rick
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