Power source switch causes occasional lockup on docked T500

[jskang]

I've got a rather interesting problem and would like some advice on the two options I'm looking at in addressing this.

I've got a T500 running Windows 7 (64-bit). When it is docked, it is running in an extended dual-display mode (one display is the notebook LCD and the other is an external LCD FP).

The office I work in has a diesel generator to deal with extended power outages. We are signed up with our electricity provider to have our office power switched from AC to generator on heavy power load days. Usually the switch from utility to generator power takes less than a second. The problem I am encountering is occasional. In some instances, when we are switched from utility to generator power, my laptop will completely lock up. Both displays stay, but I am locked out of my USB-connected keyboard and mouse. The keyboard and touchpad on the laptop go inoperative when this happens too. So, I can't close apps and do a graceful shutdown. I'm forced to hold down the power button on the laptop until it does a hard shutdown.

As I mentioned, this doesn't always happen. More often than not when our utility switches us to diesel power or back to utility, I can keep on working.

My original thought to resolve this problem was to get a very low-load UPS. I was hoping I could find them for a reasonably inexpensive price. But, it looks like the lowest end UPSes are about 350 VA and retail for around $40. Still a bit too expensive considering the infrequency of the switch in power source and the rarity of this happening. A coworker wondered if a surge protector with AVR/line-conditioning (but no battery backup) might prevent this from happening.

Anyone else have any thoughts or suggestions on this problem? If a surge protector with AVR wouldn't prevent this, then I'm probably going to just put my system into standby before the utility switches power sources on us. We get an email notification from our provider in advance of the switches happening so that is definitely the no-cost option.

[rkawakami]

My guess is that some voltage noise (spike or dip) is getting through your power system and hanging the laptop. Since you get an advance warning on when the power switches between the grid and generator, the other no-cost solution is to simply run the laptop off the battery; disconnect the dock from AC power. This assumes you can depend on it for the length of time from notification to change-over. If that is either not possible or you don't want the hassle of disconnecting/connecting the AC supply to the dock, then I would invest in a UPS that has good filtering and voltage regulation. A surge protector is useful in cases where there might be a gross overvoltage applied but it can't do anything for a voltage drop.

[jskang]

Thanks for the reply! That was roughly my thinking.

If I run off the laptop battery while connected to the dock, I won't lose the use of any self-powered USB devices that are connected to the dock?

[jskang]

I finally had a chance to try just unplugging the AC from the docking station to see what would happen. Essentially, the same thing happens as when we get switched from utility to generator, everything locks up. I think the only option at this point, if I want to be able to work through the power source change, is to invest in a lower-capacity UPS.

The other options are to either go into standby or hibernate, or to undock completely. Undocking is a hassle as I am running in a dual, extended display configuration when docked. Going into standby or hibernation would be an option, too, but again, it takes time to go into and come out of either state.

Plus, in further consideration, while we do get notified when our utility is switching us to generator, we don't always get notified when they're going to switch back.

Thanks for the input and suggestion in any case.