Either my searching is bad or is there really isn't an actual thread for dual's.Anyhoo....
Let's start with the basics, there are two kinds of ways to set up your batteries:
1) Parallel, in which + goes to + and - goes to - . It sort of acts as one battery, so the voltage (power) stay the same, and the maH (runtime) double. Sounds good and all but if power is what you need, then we turn to door number 2!
2) Series, the most common set up for a dual cell mod. It's when the polarities are + to - and + to -. Now that we've switched the batteries, they don't want to blend the maH together, but the voltage is increased intead. (Note: you must use the same batteries or you'll get a distortion on how it runs)
Here is an example that i'm not too impressed about because it just looks like a mess but the deed is done non the less. No offense to whoevers pics i got off this site
. It may look familiar like your's as well.