I have two 2s 5000 LiPO packs for a Rustler. To get the highest runtime can I just connect them to a single connector in series? Alternatively, is there a simple toggle switch configuration that would allow me to switch from the 1st to the 2nd battery? Is that a SPDT switch? Thanks in advance for your help.

You would want to run the batteries in parallel not series. Series increases cell count, parallel increases capacity

Thank you EbbTide. To be sure, that's the red wire from both packs connected and the black wire from both packs connected, is that correct? Could I put a switch between them somehow?

That's would be correct. This is an actual adapter to give you a visual representation.

As for the switch, I havent heard of one but I feel it'd be safer to just run the parallel adapter since it is pretty tough to mess that up lol

I would not use the switch really not feasible in your application. Just parallel the batteries to increase the capacity.

Pass you soon...