if you get this kind of “error” :
Dec 14 02:36:31 hostname StoreX (Dec 14, 2005 2:36:31 AM FQDN):P3:System hostname-t3 (XX.XX.XX.XX) - Unit-unit-1 - Power-Module-2 (u1pcu2) : Power supply unit has switched to battery. Fru ID: u1pcu2, Model: 300-1454-01(50), Serial Number: XXXXXX
Dec 14 02:58:31 hostname StoreX (Dec 14, 2005 2:58:30 AM FQDN):P3:System hostname-t3 (XX.XX.XX.XX) - Unit-unit-1 - Power-Module-2 (u1pcu2) : The FRU has some error. Fru ID: u1pcu2, Model: 300-1454-01(50), Serial Number: XXXXX
then be aware that a T3 performs a battery refresh every so and then (this is by default every 28 days, but can be modified in /etc/schd.conf). This battery refresh can provoke this kind of error messages which are no error at all …