A question about batteries.

[steelo]

I have a few questions on how batteries work with electric motors. Correct me if my understanding of this is wrong.

When wiring batteries in series it doubles your voltage thus giving you more power to the motor?

And if you wire batteries in parallel you double the amount of milli-amps which would give you longer running times?

I want to understand all of this before I jump in with a mod project and if I understand this correctly I have an idea that I want to try out. It won't be ground breaking, just something simple and most likely has been done before.

If there is anything else I should know about how batteries work please let me know.