normal to see a spark when connecting deans plug lipos?

[Serum]

the capacitors on the speed controller will charge up as soon as you plug in the batteries. When they are empty (the capacitors on the speedcontroller) they have got a resistance of about 0 ohm. This changes as soon as their voltage rises.

It's completely normal that you see a spark as soon as you plug the batteries into the speedcontroller. (for driving, and not for charging)

The reason why the 2nd one sparks is because this last cell you hook up with close the chain (electricity-wise) No matter how you plug them in, there will be a spark. (unless you follow the directions as mentioned on briang's site.)