Dubious. Even weak batteries probably have enough juice for an actively correcting UPS to protect things on mains.

I find that heat (bad ventilation), and fan bearings, are the only things that killed the PSUs I've seen.

But like I said, I've very little experience with things failing like that in recent times. The odd hard drive here and there -- all of them Deathstars or Seagates, and some USB gizmos, but not PSUs.

Mind you, I do use higher cost (and hopefully higher quality?) *quiet* PSUs in all of the boxes here. The last PSUs to fail for me were a pair of OEM no-name noisy little suckers.

Cheers