Hi.

I want to connect Lightbridge 2 to three 18650 batteries. But max input voltage can be 4.2V * 3 = 12.6V (EMF). Is it possible to connect Air System in this configuration?

You can always check the specs to see what the maximum voltage is. However, the set up sounds like a custom set up for which I can not advise on as you appear to be using it in a different process for what is it designed to be set up for. In this case, you may want to think twice.

Thanks for replay. I know specs (9-12V) and use LB2 to transmite HD video only. Without gimble, flight controller and other. HDMI input from camera and input power 10V throught DC-DC converter. But it will be interesting to know, can i use 18650 x 3 in serial connection.