They looked at almost a dozen different flash SSDs from seven vendors and found that they actually reduced battery life instead of increasing it. The reason seems to be that while spinning hard drives have higher power requirements on paper, in reality, peak loads are only reached when random data thatís distributed all over the medium is being searched out.
In contrast, SSDs pretty much have an idle or active state. So while conventional hard drives may operate at almost idle power when little movement is required, flash based drives will draw their maximum power level constantly when in use. Itís a very interesting read for anyone who cares about battery runtime, and shows that thereís still a lot to be done for SSDs to overtake the good old hard disk drive Ė in terms of energy efficiency, at least.