An indication of the current status of the NVRAM battery or batteries.
Batteries which are fully or partially discharged may not fully protect the system during a crash. The end-of-life status values are based on the manufacturer's recommended life for the batteries.
Possible values:
ok(1),
partiallyDischarged(2),
fullyDischarged(3),
notPresent(4),
nearEndOfLife(5),
atEndOfLife(6),
unknown(7),
overCharged(8),
fullyCharged(9).