MUCH improved battery life with replacement Storm 2

I recently had to get my Storm 2 replaced under warranty due to the speaker going bad. I received a new one with a build date of May 2010 and kept the Seideo battery that I had in my old phone.

My new one came pre-installed with .607 and I upgraded to .713 upon my return to the office. The battery life is amazingly much better with this phone compared to my old Storm 2 which was also running .713.

Is it possible that something has changed with the newer built phones to improve battery life?

I now can go a day and a half with the same usage on this phone compared to 10 hours at the most on the old one.

NOTE: same apps on both phones

some phones are like that they all react different to some os's for some reason