For transients/spikes, you could miss them regardless -- dunno how often the logging in a UPS records samples for the PC.

But ditto for a voltage meter. They take/report samples a few times per second, but a spike/transient could still be missed.

The $40 UNI-T UT61C meter I got off eBay (China) has serial output for a PC, and can keep min/max readings. Dunno if it would catch brief spikes or not. Sampling interval is 3/second I think. Would need to supply it with power though -- the batteries wouldn't last long enough, and the meter has auto-shutdown as well (to save batteries) -- kinda ruins it for this use.

There are other, similar meters from UNI-T with differing features / capabilities. Good bang for the buck.