x200 w7 64 bit freezeups on battery power

[bcherry]

This is my second x200. The first one was Vista 32 bit and I used it for a year with flawless performance. This one was purchased with W7 64 bit and freezes at least once or twice each session when on battery power but never when plugged into the Ultrabase. I can't trust this machine for use in meetings and pretty unreliable for portable use.

has 4gb memory, 80gb Intel Gen 2 SSD. Memory consumption is about 40-50% range. Have installed the latest bios.

Anyone had this problem and found a fix?

[amue]

Since it only happens when running on battery power, my first and best guess would be a defective battery.
I think you should look into that.

[bcherry]

Thanks. I also suspected that but I have 3 batteries, 2 - 6 cell and 1 - 4 cell, original and they all do the same. I think it has something to do with the higher internal impedance of battery compared to mains voltage. I believe it is a system power management problem. Never had this before.