Laptop battery life with 64 bit

[Daniel Dalton <d.dalton@iinet.net.au>]

Hi,

Before I do too much investigating I was wondering if anyone might be able to give me a simple yes/no answer to this question.

I just installed debian 64 bit amd on my Dell vostro 3350 laptop. 

I turn all of the wifi bluetooth and screen off (I'm blind) and observe power using powertop. 

It reports a discharge rate of about 9W on average. On ubuntu 12.10 32 bit with this similar configuration it was just below 6 W. 
So this is quite easily 4 or 5 hours difference (I have an 80 W battery), it is huge. 

My question: does 64 bit debian use more battery power than 32 bit? 
Battery life is very important to me, and it seems there isn't a whole lot of benefit of running 64 bit for me at the current time. 
I haven't set too much up just yet so it is easy to change. 

Should I return to a 32 bit set up if battery life is important to me? Or is there perhaps something that maybe isn't configured quite right on this 64 bit system?

Finally, I'm running debian wheezey (testing).

Thanks in advance for any help. 

Dan