To backup an RTCC or SRAM, two cells in series are needed to get 2.4V. Standard AA and AAA cells are popular and easy to be changed, but they need a battery holder.
[pdf] Although informally called a battery backup, formally the type of product we're looking at today is called an Uninterruptable PowerSupply (UPS). A UPS unit is similar to but different from a surge protector. Related: You Need an Uninterruptible Power Supply (UPS) It's one part surge protector and one part beefy battery. .
You'll find plenty of recommendations to put a UPS on your computer, especially if you're doing mission-critical work or have expensive hardware to protect, but there's not as much talk. .
In our guide to selecting a UPS for your computer, we take a deep dive into the ins and outs of calculating power loads and UPS sizing.
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