I want to build some emergency lighting equipment using LEDs and 12V. A
friend told me that it is possible to get more light per Watt by pulsing the
LED to instantaneous levels well above its average ratings.

Is this true, if you include power consumed in the pulsing circuit?

If it is, can anyone suggest a simple and cheap circuit and the appropriate
operating values?

The reason for the 12V requirement is that I'm also working on a solar
charger for my transceiver batteries and want to use the same charger for
the lighting batteries.

Suggestions would be appreciated.

Tom, N3IJ