I know that the differences in resistance between batteries in a circuit will create different drop, and as a result draw unequally. Unfortunately, I couldn't get my hands on a parallel D-cell battery holder, so I soldered one myself. On my multimeter, I measured as much as a 0.1-0.3 ohm difference between the contacts and ends of the leads, which was more than I was expecting.
I'm using these batteries: http://www.xenoenergy.com/eng/prod/genaral06.asp , and they will be deployed outside in sealed boxes for quite some time.
My question is this: how much of a resistance difference between leads on cells is 'too much' and could yield either catastrophic battery failure or meaningful decrease in battery life?