[1minusp]

I'd like to be able to do something similar, but the old batteries in these things seem like a point of catastrophic failure. How is that dealt with?

[gunapologist99]

Remove the batteries. Datacenters have redundant power and UPS.

[jhickok]

If it's an offsite backup, you would deal with it like you would any DR site-- either plan for yet another backup, or presume that it's unlikely that both the primary and replica would go down simultaneously and accept the risk.