MG Car Repair: Dead Battery, test light, test charge

Question
How would you solve a problem with the battery (new battery) in my 1980 'B' going dead overnight?

Answer
Hi Larry,
If a new battery is going dead over night you need to do a simple test. Charge the battery back up and be sure everything is turned off and then remove either battery cable and put a 12v test light between the battery post and the cable. If it lights the test light, there is a draw of some kind and you need to take a wiring diagram and start by first removing all of the wires off of the alternator and recheck the test light. If the light is still on start pulling fuses to isolate the problem to a smaller area. Once you find the area in a fuse look at your diagram and see what wires that fuse feeds and put that fuse back in and start removing one wire at a time and if you isolate it to one wire, look at your diagram to see what that wire feeds.
Howard