Laptop goes to sleep if no battery but AC plugged in

I haven't verified this yet, but I wondered if it's a possible bug?

I bought a Dell XPS M1330 over a year ago and it came preloaded with Vista Home Premium. Since I want to keep the batteries in good condition I run the laptop with no battery connected and AC plugged in whenever it sits on my desk at home.

However, in Windows 7 it seems that Windows wants to put the laptop to sleep after 10-15 minutes if I do this. Since I have various USB devices plugged in, especially external storage, this is a problem. It goes away if I run with the battery plugged in but like I said, not verified yet.

It's not bug.. It's new power management settings in windows 7.
You can easily change it just press you battery icon and press more power options
You will come up with window like this:


Now press change plan settings for the plan you are using.. After this it's very user frindly ( you can choose when dim you brightness, when put in sleep and when turn off hardware)

"Put the computer to sleep" is set to "Never" for "plugged in" in all three power profiles, but the computer still goes to sleep if the battery is not plugged in.

I ran

and it actually think my settings are an error:

Some laptops have a built in service or software that requires the battery to be in the laptop. Stick it back in and check.

Frostmourne said:

Some laptops have a built in service or software that requires the battery to be in the laptop. Stick it back in and check.

Click to expand...

This one doesn't, since it worked just fine in Vista (and Ubuntu).
Unless Dell has some special power management software that's missing from Windows 7...

It might be. Does the problem go away with the battery inserted?

If the battery is plugged in everything works fine.

I tested setting the power options for "on battery" to 1 minute and waited three minutes without touching the computer, so it's not those settings Windows uses.

I also checked the BIOS and there are no sleep or standby settings available.

Then its probably built into the dell, can you contact them to clarify?