What's heavier... 2nd hard drive +caddy or optical drive?

I just ordered a Sandisk Extreme 240GB SSD to replace the hard drive on my laptop. The current drive that I have will go in place of the optical drive. This is the first time I've done this so I'm not sure of how this will impact my laptop. I mean I know the performance will go up (I have a SSD in my gaming laptop and its tremendous) but how will it affect the weight and battery life? Will the HDD+caddy be heavier than the optical drive that I'll be taking out? How it affect battery life? I know 2 drives will draw more power technically but I feel like in most scenarios the storage drive will be idling and therefore might draw less power? I'm not sure... so for those that have done this, what does replacing your optical drive with another HDD do to your laptop in terms of weight and battery life? If the battery life gets worse... by how much?