We've had the odd complaint about poor battery life from Celeron M based Eee PCs, especially since our Eee PC 701 and Eee PC 900 review units lasted a very reasonable 2 hours 15 mins and 2 hours 49 min when reading a PDF with screen brightness set to maximum and Wifi turned off.

A recent Bios update disabled a Bios option that let you choose between performance and battery life so that the CPU would flick between 900MHz and 630MHz respectively when on battery power. But the update seems like a bit of a red herring since it didn't improve battery life substantially on my Eee PC (a different one to the one we reviewed).

A bigger issue is the quality of the battery being used, since each Eee battery appears to behave different and every one I've seen isn't calibrated properly.

With the battery fully charged, my Eee PC 900 reports 80 per cent battery life remaining as soon as it is unplugged. It then drains down to 7 per cent over the course of one hour, where it stays for a second hour before dying. Unfortunately, the default Windows power scheme puts the Eee PC into standby at 10 per cent, so many Eee PC owners aren't getting the full potential out of their batteries.

A friend's Eee PC 701 I had a play with exhibited similar behaviour, getting stuck on 30 per cent.

The cause is probably cheap logic inside the batteries being supplied with the Celeron M generation of Eee PCs and my advice is to either turn off the Windows power scheme altogether or to lower the warning levels so that your battery goes the distance it's capable of.