Hello all you electronic nerds. I have a simple question so please do not try to give me a college education in your answer. I have an 16.8 drill battery without a charger. i need to find out if it will hold a charge. I do have an adaptor that is 18 volt ac output. My question is can you charge a DC battery with AC voltage. I don't meanm leave it on the battery and walk away. I mean touch it and pull away and touch it and pull away until you have the right amount of volts in the battery? I use wall warts or adaptors all the time to recharge aa batteries by clipping the end and with a meter finding out which is positive and negitive. I use a 4 volt dc output to put a quick charge on the aa battery's and it works great. But will the same theory work from a AC to DC? tHE rAZ

I sense some frustration with not knowing some basics about electricity. Yet, you definitely have curiosity in this area. I think you might find it very satisfying to learn more, rather than dancing in the dark like this. I don't know your age, but you can learn a great deal in a high-school intro to Physics class. Or, adult education at a Vo-tech or a community college. ..... You said you wanted a simple answer, so I didn't try to tell you how to design and build the circuit that would enable you to use your 18VAC power supply. The major component is a diode (or 2), but you might need to add resistors too. A diode is an electronic component that allows current to travel in one direction, but not the other. Selecting the right one might be a challenge. (Try Wikipedia for an excellent lesson on diodes.) You might get lucky and find one at Radio Shack that will work. But many Radio Shacks don't sell parts like this any more. Regarding what you read on using magnets -- this was either a misunderstanding or complete nonsense. I sense some frustration with not knowing some basics about electricity. Yet, you definitely have curiosity in this area. I think you might find it very satisfying to learn more, rather than dancing in the dark like this. I don't know your age, but you can learn a great deal in a high-school intro to Physics class. Or, adult education at a Vo-tech or a community college. ..... You said you wanted a simple answer, so I didn't try to tell you how to design and build the circuit that would enable you to use your 18VAC power supply. The major component is a diode (or 2), but you might need to add resistors too. A diode is an electronic component that allows current to travel in one direction, but not the other. Selecting the right one might be a challenge. (Try Wikipedia for an excellent lesson on diodes.) You might get lucky and find one at Radio Shack that will work. But many Radio Shacks don't sell parts like this any more. Regarding what you read on using magnets -- this was either a misunderstanding or complete nonsense.

I've heard them called vampires, but wall-wart is a new one on me -- I like it. Anyway, using another wall-wart just might work. I think you have the right idea, but let me restate it (you threw me with the bit about putting your 18VAC as the input to the wall prongs). Sacrifice a wall wart that has the highest voltage and current rating you have (current will be stated in amps or milliamps (mA). 1000 milliamps = 1 amp. The wall wart contains a transformer, and the rest of the stuff is the rectifier. Cut the leads between them - that's important - to separate the transformer from the recitifier. Use your 18VAC power supply as input to the rectifier. It doesn't matter which wire is which with the AC. This should get you pretty close to 18VDC output. But just be forewarned, if the 18VAC power supply is big enough, and/or the battery is bad, you might toast the rectifier. Good luck. I've heard them called vampires, but wall-wart is a new one on me -- I like it. Anyway, using another wall-wart just might work. I think you have the right idea, but let me restate it (you threw me with the bit about putting your 18VAC as the input to the wall prongs). Sacrifice a wall wart that has the highest voltage and current rating you have (current will be stated in amps or milliamps (mA). 1000 milliamps = 1 amp. The wall wart contains a transformer, and the rest of the stuff is the rectifier. Cut the leads between them - that's important - to separate the transformer from the recitifier. Use your 18VAC power supply as input to the rectifier. It doesn't matter which wire is which with the AC. This should get you pretty close to 18VDC output. But just be forewarned, if the 18VAC power supply is big enough, and/or the battery is bad, you might toast the rectifier. Good luck.