What did you switch the battery in? The ohmmeter? If so, perhaps the circuitry in it is voltage sensitive. (It is very hard-- read expensive-- to build an accurate milliohmmeter; most of the good ones are hundreds of dollars and generally unusable for vape purposes as they have currents of hundreds of amperes, being intended to test motor windings. If you paid less, you probably didn't get much. The only really good way to measure such things at the level vapers need is a 4-wire Kelvin probe setup; I've never seen one, even Chinese made, less than a Franklin.) A better guess is, the difference in readings is only .04Ω. For most vape meters that's a rounding error. You might have gotten that much, or more, variance, just by twisting the atty in the 510 connector a bit. We're talking a very tiny amount