Here’s a great hack. KMart is selling these torches for about $3.50 with batteries. The LED in this is fitted to a normal sized bulb fitting, meaning it can be taken out and put directly into any 2 Cell torch, AA, C or D.
It’s a very bright 10mm LED in a normal bulb fitting. No regulator circuitry.
This has to be the cheapest source of LED drop in bulbs for torches I have found. Or you could just use the torch.
The beam is much brighter than a normal 2 cell torch. Runtime would be significant, although I haven’t done a full runtime test. You’ll use far less batteries, better for the environment.
Beam pattern is an average spread.