PRS-T1 rooted(and T2) chess battery

[trocchietto]

Dear readers and developers,chess lovers,
I reckon that rooting a device the battery will last less, also if I am curious to know indeed if the battery remains the same if I do not use at all the android interface once rooted, my question is instead slight different.

Playing chess destroy my samsung S2 battery, especially in analysis mode.
So I am wondering how would last(more o less) a T1/T2 with (after the full recharge new batteries)
1) analysis mode
2) a game against the pc

in practical terms, can I carry on one day playing chess 4-5 hours and reading for the rest of the day (other effective 8 hour) before I go sleep to recharge?

For chess supporters I was thinking to the prs+ software, they have a chess software really slow, but really optimal for a eink reader in terms of battery, if I root can I add that program with some immediate hack( really easy would be an android compilation maybe)