16. Battery Tests

THG found out how long batteries hold out based on three typical applications: DVD video playback, a 3D game and a presentation. The three application tests are separately run in a loop until the battery is completely sapped. To ensure that the CPU energy-saving mechanisms are used to best effect, we selected Portable/Laptop as our power scheme. For test purposes, we set screen brightness at around 100 cd/m² on all devices.

The following should be noted in judging battery life: At 15.4", the display on the Inspiron 8600 is larger than the Yakumo Q8M Power64 XD's and accordingly eats up more power. At 72 Wh, the battery in the Dell notebook is far smaller in performance terms (Yakumo 98 Wh). In theory at least, the Yakumo system should run longer.

The reality, however, is somewhat different. The Inspiron 8600 does run longer on one battery charge but the device falls behind the Mobile Athlon64 notebook when demand is greater for the graphics unit and, to a lesser extend, on the CPU. This is not due to the energy-saving capabilities of the CPU in the Q8M Power64 XD, however, but since our test device only runs with a maximum of 800 MHz in battery mode. Under these conditions, the Mobile Athlon64 can burn a maximum of 18 watts.

The measurements with Mobile Mark confirm the above results and show that the Yakumo device running on battery has to content itself with second place in office applications because of its fixed CPU speed.