craftsman drill and light bulb failure 19.2v system

i have used the sears craftsman drill and light combos for my business for several years---they work great with the exception of premature bulb failure---i am an electronics technician and discovered the reason for the premature bulb failure is because after a full charge the battery has 20.85v and the bulb is a 19.2v---i solved the problem by adding a 1.8ohm 3w resistor is series with the positive lead between the switch and bulb---this drops the voltage on a full charge to 18.65v to the bulb and also shunts some of the current---the voltage on a non fully charged battey is still sufficient to have minumal effect on the light output--you need to use a flame proof style (instead of wirewound) resistor to keep the physical size small enough to fit the light housing--- anyone needing additional information can e-mail me at jade7@centurytel.net