My vector vec157 will not charge on 120 volt. It works on 12 volt

If you light is charging when you use the 12v automotive charger but not when you use your AC power transformer, my thought is that you might have a problem with your AC charger, not with the light itself. I have AC/DC transformers from the 1970s that still work fine, but I have had numerous modern AC/DC transformers burn out on me in recent years.

One easy test is to use a multimeter to measure the output voltage of your wall charger. Place one test lead on each of the charging terminals (i.e., one inside the barrel and one outside the barrel, if you have a standard coaxial charging port) and check the DC reading. If it's zero--or anything less than 12 volts, actually--the charger isn't working correctly. The problem may be a torn or cut wire or something actually inside the transformer.

Replacement chargers can be found at Radio Shack and other stores. You may also be able to score a cheap replacement at a "dollar plus" store or even at a second-hand shop. Make sure that the terminal polarity is correct on your replacement charger or else you'll fry the batteries in your light.

Good luck!