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Soldered-on RTC batteries (with type covered as a bonus)
(i.imgur.com)
This battery lasts the life of the router under the operating environmental conditions specified for the router, and is not field-replaceable.
But who determines its lifespan?
Knowing there is a battery set to fail and I can't simply replace it makes me physically uncomfortable. Enough so that I'd rather it not have RTC.
Thanks Cisco.
As far as what battery it is, measure it in metric. (mm) Search up a button battery chart. One of those should have voltage and measurements you can compare against.