it really is simple to fix the problem..... with your multi-meter set up to measure amps it could only take a few minutes to fix it. just make sure your multimeter is fused. stop being lazy and fix it
Actually, your battery lasts longer in cold weather because the drop in temperature slows down the chemical reactions going on inside it. "Cold weather makes your battery die faster" is an old wives tale!
but it takes more to start your car when cold, thus draining the battery more when starting i think my sub may have a little to do with it, since my revs were going with the beat last night, no music and no hot blowers, perfect for this weather i dont think its entirely the sub though... ill just stick to disconnecting - terminal
Jolfa John_g is right. Assuming that your alternator is doing it's job, and that the so called good batteries are ok and actually holding a charge rather than having duff cells which discharge then you're either going to have to remove various electrical components one by one in turn each night i.e glove box light, boot light, alarm, stereo, relays etc and see which one makes a difference(very time consuming), or BEG,STEAL,BORROW,BUY A MULTIMETER, connect in series and measure the current drain whilst removing the same components as above. Sooner or later you should come across the culprit.
I got one from Halfrauds for 10 I think it was, very usefull at times! My car doesnt like to start either, I'm getting 13V when engine is running but all the connection under the bonnet look rough as f8ck, gonna give them a good clean up!