HP dv6500t: A "Minivan" Notebook

Battery Life

In the past, our standard battery life test has been provided courtesy of MobileMark 2005. Since the laptop isn't available with Windows XP (and we didn't have the necessary SATA drivers to even attempt installing XP), we decided to look elsewhere to determine battery life. Generally speaking, we don't expect people to seriously tax their laptops when they are unplugged, so we tried to come up with a benchmark that would simulate moderate office application use. The other most common battery life test is simply DVD playback, so we looked at that using Star Wars Return of the Jedi as our test DVD. (Don't complain -- it's a 2.5 hour movie so we didn't have to loop it more than once!)

For the other battery test, we ended up settling on Internet Explorer and simulated web surfing. We created a script that would start Internet Explorer and load our three home pages, all of which contained quite a few Flash-based advertisements. The script would then sleep for 60 seconds, simulating "reading" the web pages, and then it exits Internet Explorer and repeats the process. Internet Explorer was set to delete all temp files on exit, so it still creates a bit of hard drive activity. Basically, this test corresponds to about the best case scenario you are likely to encounter, while the DVD test is a bit more taxing.

Since we don't have similar results for the other laptops, we'll just report the two scores for each test in a table. It's not too surprising that the double capacity battery pretty much doubles battery life.

Batter Life (Minutes)
	HP dv6500t 6-cell	HP dv6500t 12-cell
Internet Explorer	133	246
DVD Playback	105	205

HP also offers a high-capacity 6-cell battery that should improve performance without adding all of the extra bulk of the 12-cell battery, but we didn't receive that battery and we're not quite sure how much more power that battery holds relative to the standard 6-cell. As it stands, the laptop either offers a somewhat limited amount of battery life, or if you get the larger battery you can end up with a pretty good mobile experience. Ideally, we would like to see minimum two hours of battery life, and probably closer to 2.5 hours as that's enough to watch just about any full-length movie on a single charge. Considering the performance isn't particularly stellar, we were hoping that battery life would be better.

Power Consumption

Related to the battery life discussions we've just finished, we have power results. For power testing, we removed the battery from the laptops and measured system power draw at the wall outlet using a Kill-A-Watt device. All laptops were configured to run at maximum performance when plugged into AC power. We tested several different scenarios to try to isolate the power draw of the various components. First, we have the baseline measurement when the system is idle and sitting at the desktop. No applications are running for 10 minutes or more and the screensaver and hard drive sleep mode are disabled. As a CPU load test, we run two instances of Folding@Home at 100%. Finally, for maximum power load we leave the two folding instances running and start 3DMark05. In this way, we can see roughly how much power the GPU is using in 3D mode versus 2D mode.

System Power Draw (Watts)
	ABS Mayhem Z5	ASUS A8JS	ASUS G2P	HP dv6500t
Idle	44-49	26-32	43-52	22
100% CPU	67-71	47-52	71-81	57
Maximum	100	71	97	67

Looking at the power requirements of the system, the somewhat disappointing battery life is at least partially explained. At idle, power requirements aren't bad at all, but when the CPU is under load the power of requirements are quite a bit higher. We also noticed that the CPU had a tendency to not kick into the lowest power states; we discovered this using CPU-Z and the processor almost always stayed in the 8x configuration at idle, only bouncing up to 10x when one of the cores was placed under load. Normally, at idle, we're used to seeing the CPU dropping to the minimum power state -- in this case 1.0 GHz. It could be that the slight load that CPU-Z put on the system was preventing this from happening, but it also seems that Windows Vista was impacting the situation. Compared to the ASUS A8Js, the larger screen, hard drive, and faster front side bus all seem to balance out and result in a system that consumes only a bit less power at idle and quite a bit more power at load.